When I first started researching this piece, I assumed there was a standard test that could give us our muscle creatine level. A simple blood panel. Something a doctor could order on a Tuesday afternoon.

Oh boy, was I wrong.

After working through several peer-reviewed papers, looking at clinical trial methodology, and a conversation with a physician friend who confirmed my suspicion that this is not as straightforward as the supplement industry implies, here is what I actually found.

The Creatine test confusion

Before we talk about a personal creatine baseline, there is some confusion worth clearing up first. It trips up almost everyone who starts supplementing and then gets a blood panel back. A lot of people see “creatinine” on their lab report and mistake it for “creatine.” They assume the doctor is directly measuring their muscle fuel or tracking some kind of creatine ratio. But the kidneys don’t actually deal with creatine itself. They deal with creatinine, which is the waste product left behind after your muscles burn that fuel. It circulates in your blood until it is filtered out by your kidneys.

Think of it like a car. Creatine is the fuel sitting in the tank, ready to power the engine. Creatinine is the exhaust left behind after that fuel has been burned. Measuring the exhaust tells you some information about how the system is running; it does not tell you how much fuel is actually in the tank. This confusion comes down to a simple naming issue, but mixing up the asset with the waste product completely distorts what the blood test is actually looking at. Next time your doctor orders a kidney function test, the number that comes back will be your serum creatinine level, not the creatine stored in your muscles.

Creatinine

Skeletal muscles continuously release creatinine into the bloodstream as they burn creatine for energy. That means the amount of waste the body produces depends mostly on how much muscle you have and how active you are, not on how well your kidneys work. Someone who is physically active and carries significant muscle mass has larger creatine stores, so they naturally produce more creatinine waste every single day, even with perfect kidneys. Their baseline creatinine is just higher, and that is completely normal physiology, not a sign of kidney trouble. Checking a single blood test and assuming it means kidney damage completely ignores basic biology and gives you a false reading.

Age complicates the picture further due to two major factors.

1. Muscle mass generally declines with age.

2. Kidney filtration gradually decreases with age.

Those two changes can pull serum creatinine in opposite directions, which is part of why this number is less straightforward than people assume.

This is exactly why clinicians do not stop at creatinine alone. They calculate eGFR, the estimated Glomerular Filtration Rate, which factors in age and sex alongside the creatinine level to provide a much better estimate of actual kidney function, although, like any estimate, it has limitations. And if a result still looks ambiguous after that, there are more specific follow-up tests. Cystatin C is one example, a protein produced by the body at a steady rate that is not affected by muscle mass, which can help clarify whether an elevated reading reflects muscle mass, diet, supplementation, or an actual kidney concern.

What this means if you are taking creatine

If you start supplementing, your next blood panel will show a mildly elevated serum creatinine level. This is a known and well-documented finding in healthy people. Creatine supplementation can produce a small increase in serum creatinine because more creatine is available inside the body to undergo its normal, ongoing conversion into creatinine. On its own, in someone with normal kidney function, this is not evidence of kidney damage. It is exactly what biology predicts.

This is one of the most common sources of unwarranted alarm in creatine literature, and it is worth knowing before you ever see the number, not after you have already panicked at a routine physical. If a reading does come back elevated, the right response is not to assume the worst.

So, How Do You Actually Measure Your Creatine Baseline?

The short answer is: not easily, and probably not at your next GP appointment.

Here is what exists at each level, from what is available today to what is coming.

What a standard blood panel gives you

A routine metabolic panel measures serum creatinine and calculates your eGFR from it. As we covered earlier, this only tells your doctor how well your kidneys filter out waste. It cannot tell you how much creatine is actually stored inside your muscles. These are entirely different numbers measuring entirely different things, and confusing them is the most common mistake people make when reading their own lab results.

If the gold-standard muscle biopsy tests are locked away in research labs, what about other blood markers?

That is where plasma creatine comes in. This is a real medical measurement, and it is completely distinct from creatinine.

Plasma creatine reflects the amount of creatine circulating in the blood at a given moment, before it is taken up by tissues and undergoes normal metabolic turnover. In one of the largest population studies to measure this directly, the PREVEND study, mean plasma creatine concentrations were around 42 µmol/L in women and 29 µmol/L in men, with substantial individual variation around both averages. The exact values can vary depending on the laboratory, analytical methods, diet, and individual factors, so no single number can be applied universally. What is consistent across all the creatine studies is the sex difference: women generally have higher plasma creatine concentrations than men, likely because lower average muscle mass means less creatine is being taken up into storage, leaving more in circulation at any given time.

The problem? Plasma creatine is not included on standard blood panels, and most clinicians never routinely order it. More importantly, medicine has no established clinical threshold to tell you what your number actually means. There is no validated “low” cut-off that proves you need to supplement, the way there is for Vitamin D or ferritin. Even if you convince your doctor to order the test, there is little evidence-based guidance on how to interpret the result for otherwise healthy people considering creatine supplementation.

This highlights a confusing twist. A higher plasma creatine level does not always indicate higher muscle stores. In fact, in some situations, a higher number may reflect lower muscle uptake or lower muscle mass rather than larger creatine stores. Because plasma creatine is influenced by so many variables, blood levels simply are not reliable predictors of how much creatine is actually stored inside the muscle.

Think about it like a storage tank. Imagine two people—one highly muscular, one with very little muscle—and both take a 5-gram scoop of creatine powder.

The muscular individual has a much bigger reservoir capable of taking up that creatine over the next several hours, so their plasma creatine levels tend to fall more quickly after supplementation.

At the same time, because the person with less muscle has a lower total storage capacity, a greater proportion of that absorbed creatine remains in circulation, causing a larger temporary spike in their blood before it is eventually filtered by the kidneys and excreted in their urine.

Over time, some of the body’s total creatine pool naturally converts to creatinine every single day. Because supplementing increases the total amount of creatine available in the body, serum creatinine waste can rise slightly in some people, even when their kidney function is completely normal.

Ultimately, the relationship between what is floating in your bloodstream and what is locked inside your muscles is not straightforward; it is complex and often counterintuitive. The number exists. What it means for you personally is difficult to say.

What most people actually do

In the absence of a practical clinical test, what almost everyone does is estimate their likely position in the population range based on the factors that shift it. Sex. Age. Total muscle mass. Dietary pattern.

A 65-year-old vegetarian woman is almost certainly sitting near the lower end of the range, likely 100 to 110 mmol per kg, possibly lower.

A 30-year-old male omnivore who resistance trains three times a week is probably near the middle to upper end, 125 to 135 mmol per kg or above.

Neither of them has a precise number. But for the practical question of whether supplementation is likely to produce a meaningful response, the estimate is usually sufficient. The people most likely to benefit are also, in most cases, the easiest to identify without a test.

The math is imprecise. But the direction it points is reliable. So let’s do some math.

The total creatine pool, comprising free creatine and phosphocreatine, is about 120 to 130 mmol per kilogram of dry muscle mass in an individual consuming a diet containing meat and seafood. The range across the general population runs from approximately 100 mmol/kg at the lower end to about 140 mmol/kg at the upper end.

To translate that into grams of total body creatine, the calculation is straightforward but requires two numbers: your muscle creatine concentration in mmol/kg dry mass, and your total skeletal muscle mass in kilograms.

Now, let’s look at the math using a 150-pound (68 kg) person who carries roughly 64 pounds (29 kg) of wet skeletal muscle.

To determine the actual creatine storage, we first need to apply a wet-to-dry conversion, since muscle tissue is roughly 75% water. That means our 64 pounds (29 kg) of wet muscle is actually about 16 pounds (7.25 kg) of dry mass.

That is where the commonly cited “120 grams of total body creatine” figure actually comes from. It does not represent the whole body — it is only the muscle fraction. It also completely assumes average muscle mass, average concentration, and a standard diet. Change any of those three inputs, and that number shifts instantly.

How gender changes the calculation

The tissue concentration is essentially the same between men and women, both averaging around 120 mmol/kg dry muscle mass. The divergence is in the total pool and is driven entirely by differences in total muscle mass.

For example, let’s take a typical young adult man who carries roughly 35 to 40 kilograms of skeletal muscle. A typical young adult woman will carry roughly 23 to 28 kilograms. Running the same calculation:

Same concentration per kilogram of tissue. About 35 to 40 percent less total creatine in the pool, purely because of the difference in how much muscle is present.

There is a secondary factor that does not show up in the biopsy numbers but is clinically relevant: median plasma creatine concentrations are higher in females than in males, at 41 micromol/L versus 28 micromol/L. Women circulate more creatine in their blood relative to men, possibly because lower muscle mass means less uptake of circulating creatine into storage, leaving more in circulation. This is not a sign of higher reserves. It may actually reflect the opposite, less muscle available to absorb what is circulating.

Hormonal fluctuations during the menstrual cycle, pregnancy, and menopause add further variability in women, and the standard baseline numbers will not capture this. This makes women a particularly responsive group to supplementation, but the gender influence on creatine levels remains an understudied area in the existing literature.

How age changes the calculation

Older adults tend to have lower creatine levels in their outer thigh muscles. This decline happens mostly because aging triggers a loss of fast-twitch muscle fibres that store the most creatine. Changes in diet and physical activity could also contribute to these changes.

Type II muscle fibres are the fast-twitch fibres, and they hold significantly more creatine per kilogram than slow-twitch Type I fibres. As we lose these fast-twitch fibres to age-related muscle wasting (sarcopenia), the average creatine concentration in older muscles drops. Biopsy data and supplementation studies in aging adults suggest that baseline muscle creatine in adults over 65 tends toward the lower end of the normal range, likely between 100 and 110 mmol/kg, driven primarily by the preferential loss of fast-twitch muscle fibres, which store the most creatine per kilogram of tissue.

The combined effect of lower concentration and reduced total muscle mass compounds with age:

When an older adult or a woman takes the exact same dose, that powder enters a completely different environment. First, they have less overall muscle mass, meaning their absolute storage capacity—the physical size of the tank—is smaller. Second, due to age-related fibre loss or hormonal differences, the muscle they do have is running on fumes, sitting right at the bottom of the normal concentration range. Because they have both a smaller tank and a lower fuel level, supplementation hits them like a tidal wave. That is the biological reason why women and older adults experience the largest, most dramatic performance spikes in research. It isn’t some medical anomaly. It is just basic math.

This double whammy of a smaller muscle tank and a lower baseline fuel level is exactly why a standard one-size-fits-all dosing guide doesn’t make sense. Because their total storage capacity is smaller, an older adult or a smaller woman might easily max out their muscle stores on a lower daily dose—say, just 3 grams a day. Meanwhile, a muscular, young guy with double the muscle mass might need a full 5 grams a day just to keep his larger tank saturated. While those specific numbers are completely hypothetical, the underlying logic is non-negotiable: your ideal daily dose ultimately depends on how much muscle you are trying to fuel.

Anything you take beyond that personal ceiling can’t be stored; it just spills into your blood, hits your kidneys, and becomes expensive urine.

The gold standard that is not available to you

The gold standard is a needle biopsy of the vastus lateralis — dried, analyzed in a laboratory, and reported in millimoles per kilogram of dry mass.

This is how every number in the preceding sections was originally established. It is accurate, specific, and not something your doctor will order for you. It is a research procedure used in specific clinical trials and elite sports medicine settings. It requires specialist equipment and interpretation and carries a small procedural risk. For research purposes, it stays irreplaceable. For routine clinical use, it does not exist.

The most promising method that is not quite here yet

The D3-creatine dilution method is worth knowing about because it is the most likely bridge between high-tech lab research and your local doctor’s office.

The method is beautifully simple. You swallow a small, harmless dose of tagged creatine — specifically, creatine that has been labelled with a safe, stable isotope called deuterium-d3, making it chemically identical to normal creatine but traceable in the body. Because your muscles are your body’s main creatine storage tank, they absorb this tagged fuel and naturally turn it into tagged waste creatinine.

A few days later, you give a urine sample. Researchers look at how much that tagged waste was diluted by the normal, untagged waste already in your system. By looking at that dilution ratio, they can mathematically calculate your exact total muscle mass, and by that, the creatine storage capacity and baseline. No needles, no giant scanning beds, and no strict dieting required.

This method is completely non-invasive, highly accurate, and has actually been shown to beat standard DXA body-fat scans for measuring real muscle tissue. Right now, scientists are using it in major Canadian clinical trials to track age-related muscle loss over time.

You can’t walk into your regular doctor’s office and request it today. But as muscle wasting becomes a massive healthcare priority, this is the exact technology that will likely make tracking your personal creatine baseline accessible in the next decade.

What Your Doctor Can Actually Tell You

You cannot walk into a clinic and ask for your muscle creatine concentration. But there are two things a standard panel can tell you that are relevant:

Serum creatinine, interpreted alongside your eGFR, tells you whether your kidneys are clearing the waste product of creatine turnover normally. If your eGFR is normal and your creatinine is slightly elevated, and you have substantial muscle mass or are supplementing, that is expected physiology, not a red flag.

Higher estimated intramuscular creatine concentrations were associated with lower all-cause mortality in females, with a weaker trend in males. This is a recent finding from a large population study, and it is worth noting because it suggests that intramuscular creatine may have health relevance beyond athletic performance. But the method used to estimate intramuscular creatine in that study was not a biopsy — it was calculated from plasma creatine and the transcellular gradient. This approach is still in research territory and is not something your doctor will offer you as a standard test.

The practical reality is this: your personal muscle creatine baseline is a number you will almost certainly never know precisely. What you can know is where you probably sit relative to the population range, based on your sex, age, diet, and muscle mass — and therefore how much room you likely have before supplementation runs out of road.

The Brain: A Different Story

Everything above has a clean answer because muscle creatine has been measured the same way, by biopsy, for decades. The brain does not have that luxury yet, and it is worth being honest about why.

Your muscles get creatine almost entirely from diet, your own synthesis, or supplementation, all feeding into one measurable pool. The brain does not work quite the same way. Creatine can cross the blood-brain barrier through a dedicated transporter, but neurons can also make their own creatine locally. That means brain creatine is a mix of what arrives from circulation and what gets manufactured on site, and right now there is no agreed method for separating the two or defining what a healthy total should be.

This is why you will not find a brain equivalent of 150 to 160 mmol per kg dry mass. That number exists for muscle because Hultman and Greenhaff measured it directly, in biopsied tissue, in the 1990s. Nobody has produced that number for the brain, because nobody can biopsy a living brain the way you can biopsy a thigh muscle.

What researchers can do is scan the brain using magnetic resonance spectroscopy and watch creatine levels change with supplementation. And what those scans show is genuinely encouraging, if still early. In a small Alzheimer’s trial, brain creatine rose in 85 percent of participants after eight weeks of supplementation by an average of 11 percent. In healthy adults given a single large dose before a night of sleep deprivation, brain creatine rose within hours, and cognitive performance held up better than in those given a placebo.

But the dosing picture is still inconsistent in a way that matters. One randomized controlled study gave healthy young adults either 10 or 20 grams of creatine per day for six weeks. Despite those doses being higher than what several earlier studies used to show cognitive benefits, brain creatine did not increase significantly. The researchers concluded that higher doses, longer duration, or both may be needed to reliably elevate brain creatine in healthy people with normal baseline levels.

The honest summary

Supplementation does raise brain creatine. That much is established. Low starting levels do appear to predict a bigger response (or a higher creatine uptake), the same pattern seen in muscle. But there is no confirmed number that tells you your brain has enough, no agreed ceiling, and no settled answer for how much, or for how long, you would need to supplement to reach whatever that number turns out to be.

Anyone who tells you otherwise is filling a gap that the research has not yet filled.

This is just the beginning of the Creatine Brain Series.

We’ve already covered:

What Creatine Actually Does to Your Brain - Importance of creatine to your brain health

Creatine for the Healthy Brain: Dose, Timing & Real Effects - The specific protocols to supplement creatine, and who could be deficient and what you should do.

Your Steak Is Lying to You: The Creatine Content Reality - How much creatine do you get from cooked food

I am pulling together the clearest, most practical roadmap available — combining the latest research with real-world application so you can actually use this information.

If you want the full picture, the practical protocols, the individual breakdowns, and the updates as new studies drop, the rest of the series is where it all comes together.

Stay tuned — the next installment is dropping soon. This is one of the most actionable areas in brain health research right now, and the field is moving fast.

Fuel my day? ☕️🚀😊

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9. Benton D, Donohoe R. The influence of creatine supplementation on the cognitive functioning of vegetarians and omnivores. British Journal of Nutrition. 2011;105(7):1100-1105.

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14. Candow DG, Forbes SC, Chilibeck PD, et al. Creatine O’Clock: Does Timing of Ingestion Really Influence Muscle Mass and Performance? Frontiers in Sports and Active Living. 2022;4:869071.

15. Roitman S, Green T, Osher Y, Karni N, Levine J. Creatine monohydrate in resistant depression: a preliminary study. Bipolar Disorders. 2007;9(7):754-758.

16. Juneja M, Bhatt K, Bhatt D. Creatine Supplementation in Depression: A Review of Mechanisms, Efficacy, Clinical Outcomes, and Future Directions. Cureus. 2024;16(3):e56117.

17. Kreider RB, Jäger R, Purpura M. Bioavailability, Efficacy, Safety, and Regulatory Status of Creatine and Related Compounds: A Critical Review. Nutrients. 2022;14(5):1035.

18. Jäger R, Purpura M, Shao A, Inoue T, Kreider RB. Analysis of the efficacy, safety, and regulatory status of novel forms of creatine. Amino Acids. 2011;40(5):1369-1383.

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The last article ended with a promise. Before you ever open a supplement tub, it is worth knowing where you actually stand.

That depends on more than diet alone. Your age, lifestyle, underlying health conditions, sleep, and a handful of other factors all shape your starting point. But food is where the biggest differences live, and it is the piece almost nobody talks about honestly.

Most creatine content skips this conversation entirely. It assumes you are already supplementing and jumps straight to dosing. That is part of why creatine got boxed into a fitness product. People who do not lift weights tuned out, and some tuned in just long enough to decide the whole culture was not for them. The biology never got a fair hearing.

Here is the reality and what the biology actually says. We all need creatine. Our brains and muscles depend on it. it. But the starting line is not the same for everyone. An omnivore eating red meat three times a week and a vegan eating no animal products at all are not just at different points on the same line. They are operating from fundamentally different baselines, and that changes what supplementation does, how much you need, and how strongly you are likely to respond.

This article does the calculation honestly, group by group.

In this article:

• Why natural food sources and supplements are not interchangeable — and the reality of how much creatine actually reaches your body

• Why a pan-fried salmon fillet and a measured scoop of powder are not interchangeable, even if the numbers on paper look similar

• The specific cooking methods that preserve the most creatine versus the ones that quietly destroy it

• The real gap between what a typical omnivore diet delivers and what the cognitive trials actually used — and why that gap is bigger than almost anyone realizes

And in the next article:

• A full breakdown of every major food group and exactly how much creatine each one contains — meat, fish, dairy, eggs, and yes, plant foods too, with honest numbers for each and how much creatine you get to use inside the body

• Why the cheapest creatine on the market outperforms products costing three times as much, and what to actually look for on a label

• Which diet type starts furthest behind before they ever open a supplement tub — and which group has the strongest science for supplementation

Why food-based creatine is more complicated than it looks

Creatine occurs naturally in animal muscle tissue. The richest sources are the ones you would expect — red meat, pork, fish. But the amount of creatine you absorb from food is not the same as the amount sitting in the raw ingredient, and that gap matters more than most people realize.

What Your Pan Is Actually Doing to Your Creatine

Heat is the first problem, and it is worth understanding exactly what heat does rather than just knowing it causes loss.

Creatine is heat-sensitive. How much survives cooking depends on two variables: temperature and time.

Read more

Nadia read the first article. She understood the mechanism. She knew why her brain cared about creatine as much as her muscles did. She knew her low-meat diet probably put her baseline on the lower end.

But she had more questions. The ones that actually matter.

“Okay. But what do I actually do?”

How much should I take?

Is there an exact protocol, or is everyone just guessing?

When do I take it, and does timing actually matter?

How long before anything kicks in?

Are there side effects I should know about?

What does safe actually look like, and what does the data say?

And is the standard advice even right for someone like me, or is this another one-size-fits-all recommendation that ignores everything individual about my biology?

These are the right questions. And they deserve better answers than most creatine content provides.

This article is built on peer-reviewed clinical trial data and published research, not supplement marketing or fitness forum consensus. The protocols here reflect my interpretation of that evidence as a neuroscientist with over twenty years of research experience in aging and neurodegeneration, adjusted for age, diet, health status, and the reality that nothing in human biology works the same way for everyone. You will leave with a specific starting point that fits your situation, not just a generic number.

Why a healthy person might consider creatine

Why do we need creatine as healthy adults? It is not to fix something broken inside our body. Creatine is about supporting something that works, so it keeps working well as we age.

Here are the groups with the strongest rationale, and the daily scenarios that bring each one to life.

Read more

Nadia is 47. She teaches high school. She is not an athlete, not sick, not deep in the wellness world.

But three things happened in the same month. Her gym colleague, also in her mid-40s and not an athlete, started taking creatine and kept saying her energy was better. Then Nadia heard it mentioned on a longevity podcast. Not a fitness podcast — a longevity one, the kind that talks about mitochondrial function and inflammation markers. And then she came across it being discussed in a thread about brain fog in perimenopause.

She Googled it and got bodybuilding forums, supplement ads, and a Reddit argument about kidney damage. She sighed and closed all the tabs.

Nadia just wanted a simple answer: what does creatine actually do? Not what a salesperson claims, but what does biology say? Can it be beneficial to me?

This article aims to provide a clear, science-based explanation of what creatine does in your body, separating the biological facts from marketing and online claims, and clarifying whether there are benefits beyond bodybuilding.

Your body already makes creatine.

The first thing worth knowing, and it tends to surprise people, is that creatine is not foreign to your body. You are already making it. Every day, your liver, kidneys, and pancreas synthesize creatine from amino acids. You also get it from food: a standard serving of beef or salmon contains roughly one to two grams.

If you eat meat regularly, your body currently contains 120–140 grams of creatine, most of which is stored in skeletal muscle. By contrast, if you eat little or no meat, as in Nadia’s case, where she has chicken once or twice a week and rarely eats red meat, your body stores are typically 10–20% lower than average.

That gap in storage or having lower creatine levels is not a disease. But it matters once you understand what creatine actually does inside your cells.

The mechanism: phosphocreatine and the ATP problem

Your cells run on ATP (adenosine triphosphate), the molecule your body uses as energy currency. Every muscle contraction, every neuron firing, every single heartbeat spends ATP. The problem is that your cells cannot store much of it. At full exertion, you could exhaust your entire supply in seconds.

This is the problem creatine solves.

Inside your cells, creatine exists in two forms: free creatine and phosphocreatine. Phosphocreatine carries an extra phosphate group. When your ATP, the energy currency, runs low, phosphocreatine donates a phosphate group to regenerate it almost instantaneously. The reaction takes less than a second.

Here is a way to picture it: ATP is the fuel your cells actually burn. Phosphocreatine is the reserve tank that refills the fuel on demand, faster than any other system in your body.

This is why athletes first noticed creatine. Explosive efforts like sprinting and heavy lifting demand rapid ATP turnover, and this is exactly where the phosphocreatine system matters most. The performance data is among the most replicated findings in sports science.

Why your brain cares about this more than your muscles do

Here is where it gets more interesting than the bodybuilding world let on.

Your brain is about 2% of your body weight. It consumes about 20% of your body’s energy. Neurons fire constantly, processing, signaling, and regulating, and every single firing costs ATP. Unlike muscle, your brain does not get rest days.

Brain cells maintain their own creatine supply independently of the rest of the body. In practice, this means that when neurons are under metabolic stress, sufficient brain creatine availability can keep them firing continuously. Run that supply low and neuronal function suffers. This is established biology, not a hypothesis.

This is why researchers began investigating creatine and its links to cognition: not from a theoretical leap, but from the mechanism itself. The rationale follows directly from the mechanism. Neurons are among the highest energy users in the body, and they depend on the phosphocreatine system to keep firing under demand. If that rapid-recharge system matters anywhere, it matters in the brain.

Nadia’s question, whether creatine could help with the cognitive fatigue she has noticed this year, is scientifically reasonable. Whether the evidence supports it for someone in her situation is a different question. That is what the next article covers.

What happens at the extremes

The clearest evidence of how essential creatine is comes from rare cases in which the body cannot make or transport it at all, suggesting that a component of the creatine metabolic pathway is mutated or nonfunctional. When that happens, the consequences show up early. Genetic mutations that affect creatine synthesis or the cellular transport of creatine can result in serious childhood conditions such as intellectual disability, language delays, and seizures. I raise this not to alarm, but because nothing illustrates the stakes of a molecule more clearly than its complete absence or its lack of natural functionality in the body.

Most people reading this are nowhere near clinical deficiency. But there is a meaningful spectrum between clinical absence and optimal levels, and more people sit closer to the lower end than they might expect.

• Vegetarians and vegans are the best example. Without dietary meat or fish, the body relies entirely on its own ability to synthesize and distribute creatine. Studies have consistently shown that vegetarians’ muscle and brain creatine levels are lower than those of omnivores.

• Older adults are another. Creatine synthesis declines with age, quietly and without obvious outward symptoms at first. But a decline in creatine could lead to fatigue and cognitive slowing, and is usually blamed on “aging” rather than addressing creatine as a root cause.

• Women in perimenopause and menopause are a group that researchers are only beginning to study properly in this context. Hormonal shifts broadly affect energy metabolism, and early data suggest that creatine levels may also be affected.

• And then there is the category that does not get discussed enough: outwardly healthy people under sustained cognitive load, not athletes, not patients, just people whose minds do not get to clock out, whose days run long and whose sleep runs short, who may be drawing on their creatine reserves at a higher rate than they are replenishing them.

  

On the upper end, excess creatine is converted to creatinine and excreted in urine. This means your blood creatinine level will rise when you supplement. This is expected and does not indicate kidney damage, though the confusion between the two is one of the most common misunderstandings in this space, and one I will address directly in a later piece.

At high doses, some people experience gastrointestinal discomfort, bloating, and nausea. Splitting doses across the day typically resolves this issue. But high doses for several years can have their side effects too. We will talk more about this soon.

What the hype gets right, and where it overreaches

Creatine is one of the most studied supplements ever tested in clinical trials. The mechanism is well established, and the athletic performance data are solid across a wide range of populations, from competitive athletes to older adults. More recently, researchers have begun to ask what creatine does for the brain and long-term health. The early findings are interesting. The conclusions are not yet.

But the hype consistently overreaches in three directions.

1. Scope. Creatine is not a treatment for any disease. Some of the claims circulating online, particularly around Alzheimer’s and Parkinson’s, go well beyond what the current evidence supports.

2. Universality. It does not work the same way for everyone. Baseline creatine levels, diet, age, and individual genetics all shape whether you respond, and how much.

3. Safety assumptions. What is low-risk for a healthy adult in their thirties requires very careful consideration for someone with kidney disease, certain metabolic conditions, or specific medications. The supplement industry’s one-size-fits-all framing is not just unhelpful in those cases. It is dangerous.

My position is straightforward. The science of creatine is genuinely interesting, and we need to understand it better. What I have no patience for is the layer of financial motivation and overclaims that ride the creatine science with hypes and misinformation. In most cases, this can be dangerous. This series exists to strip that away.

Where Nadia goes next, and where you might too

Nadia now understands the mechanism. She knows her low-meat diet likely puts her baseline on the lower end. She knows why her brain is as relevant a target as her muscles.

What she does not yet have is a protocol. Dose, timing, what to test before starting, realistic timeline, what to monitor. I will lay all of that out in the next article, the full evidence-based guide for a healthy adult with no diagnosis.

If you have an underlying condition, a family history of neurological disease, or are on medication, those situations have their own dedicated pieces later in this series.

The goal is not to tell you whether to take creatine. It is to give you enough of the actual picture to make that decision, with your doctor, from a position of real understanding.

Coming in this series

The healthy brain protocol.

Creatine and disease: which conditions connect and why? The Alzheimer’s and Parkinson’s data.

Creatine and the kidney: what the safety data actually shows.

The cancer angle. Contraindications and interactions.

And the precision medicine angle, why your individual biology changes everything.

If this was useful, share it with someone who has been asking the same questions Nadia was.

Fuel my day? ☕️🚀😊

I spent part of my research career studying planaria. If you have never heard of them, they are tiny flatworms that are, for all practical purposes, biologically immortal.

Here is what makes them remarkable: they have an enormous, essentially inexhaustible pool of stem cells called neoblasts. These cells can divide as often as needed, replacing damaged tissue … and they do so without the telomere shortening and cellular senescence that limit human cell division. Cut a planarian in half, and both pieces regenerate into complete animals. Their regenerative capacity is not a metaphor. It is literally unlimited.

So why are we not trying to make humans more like planaria?

Because in humans, a stem cell that divides without restraint is not immortal. It is cancer.

This tension sits at the heart of everything happening right now in longevity science. And it is why, after more than 20 years in this field, including a postdoc at the Buck Institute for Research on Aging, I have come to focus not on how long we live, but on how well.

The Biology of Why We Age (And Why Fixing It Is Not Simple)

Human cells are not planaria cells. We have built-in brakes on cellular division. Telomeres shorten each time a cell replicates, eventually triggering senescence, a state in which the cell stops dividing but also begins releasing inflammatory signals that damage surrounding tissue. This is not a design flaw. It is a tumor suppression mechanism. The price of not getting cancer in your 30s is that your tissues gradually lose their ability to repair themselves as you get older.

Most human organs have very limited regenerative capacity to begin with. The gut, the liver, and the skin can do it reasonably well. The brain, the heart, skeletal muscle at scale ... not so much. And what regenerative capacity we do have declines with age as the stem cell pools shrink and their function deteriorates.

This is the biological backdrop for what the regenerative medicine field is currently pursuing: Yamanaka factors. These are transcription factors that can reprogram adult cells back toward a more stem cell-like state. The idea is to restore some of that lost regenerative capacity, replace damaged tissue that the body can no longer replace on its own, and push back the clock on aging tissue.

I find this work genuinely fascinating. I also think it needs to be approached very carefully. Reprogramming cells to behave more like stem cells is, at a mechanistic level, not far from what happens when normal cells become cancer stem cells. The delivery methods, usually viral vectors, add another layer of complexity. And the individual genetic variation across real human populations means that what works safely in one person may not work safely in another.

Think about the 2007 Will Smith film I Am Legend. In the movie, Scientists engineer a virus to cure cancer, and it worked very well in the lab. But viruses always mutate, and the resulting mutation can be devastating, and the consequences scale in ways nobody predicted.

Now … I am not saying that is going to happen. But as a scientist who sees the methodology and the caveats behind the headlines, I find that the film captures something real. When you introduce any biological intervention into a large, genetically diverse population, or as I call it, “a population that is not one size fits all”, the range of responses grows in ways a controlled trial simply cannot anticipate. This is not science fiction thinking. It is basic population biology, and it is a reason for genuine scientific humility as this field moves forward.

So What Do I Actually Promote?

Healthspan over lifespan.

Lifespan is just a number: the total years between birth and death. We have gotten good at extending it. What we have not gotten good at is making those extra years worth living. Right now, a large portion of the years we have added to human life are spent managing chronic disease, cognitive decline, and physical frailty. That is not the goal I am working toward.

Healthspan is the years you live well. Cognitively sharp. Physically functional. Not dependent. The science I care about is the science that extends that window, not just the total count.

Things That Actually Move the Needle Right Now

This list is not exhaustive. These are the things coming to mind as I write this, areas where the evidence is strong enough and the interventions accessible enough to be worth talking about now. There is more. There is always more. But let’s start here.

Precision medicine

Population-level advice is a starting point, not an endpoint. Your genetics, your history, your microbiome, and your individual risk factors all shape what the right intervention actually is for you. What works for most people may not work for you, and what works for you may not work for most people. The more we move toward truly personalized approaches, the better the outcomes will be.

Biomarkers and early detection

Alzheimer’s and Parkinson’s disease start silently, typically 10 to 20 years before any symptoms appear. Blood-based biomarkers for amyloid, tau, neurofilament light chain, and alpha-synuclein are becoming clinically relevant. Catching these processes early, while the intervention window is still wide open, changes the equation entirely.

Sleep

I think sleep is the most underrated aging factor in most people’s lives. During sleep, the brain clears amyloid and tau through the glymphatic system. Chronic poor sleep drives inflammation, insulin resistance, cortisol dysregulation, and accelerated neurodegeneration. None of the supplements people spend money on will compensate for consistently bad sleep. This one is not negotiable.

Diet, exercise, and stress

I know these sound like things your doctor has been saying for 30 years. They sound that way because the evidence behind them is overwhelming. Regular physical activity reduces Alzheimer’s risk by 30 to 40 percent. Anti-inflammatory dietary patterns protect dopaminergic neurons. Chronic stress accelerates brain aging in ways we can now measure. These are not soft lifestyle suggestions. These are the best-validated interventions we have.

Chronic inflammation

Inflammation connects almost everything on this list. It runs through neurodegeneration, cardiovascular aging, and metabolic decline. It is the common thread underneath poor sleep, chronic stress, a bad diet, and a sedentary life. During my time at the Buck Institute for Research on Aging, a lot of my work touched on inflammatory pathways, and it became clear that you cannot separate brain aging from systemic inflammation. They are the same problem showing up in different places.

Oral health and the microbiome

This one surprises people. But the connection between oral bacteria and brain disease is no longer fringe science. I worked at Cortexzyme, where we were researching Porphyromonas gingivalis, the primary bacterium in chronic gum disease, and its potential role in Alzheimer’s disease. The data suggested that gingipains, toxic enzymes produced by P. gingivalis, may be present in Alzheimer’s brain tissue and could be contributing to neurodegeneration. This work is still evolving, and I want to be careful not to overstate it. But the oral-brain axis and the gut-brain axis are real, and what lives in your mouth and gut does not stay there.

Metabolic health and blood sugar regulation

Insulin resistance and poor metabolic health are associated with increased cancer, Alzheimer’s risk, and Parkinson’s, and the mechanisms make biological sense. I want to be clear about one thing, though: I do not subscribe to the framing that Alzheimer’s is a Type 3 diabetes. That label implies a causality that gets the sequence wrong. The metabolic dysfunction we see in many Alzheimer’s patients looks more like a downstream consequence of neurodegeneration than a root cause driving it. The relationship is real, but it is not that simple. What I will say is that keeping metabolic health strong, staying insulin sensitive, and managing blood sugar is worth doing for your brain, regardless of how we eventually sort out the mechanistic debate.

Social connection and purpose

Loneliness is now one of the better-documented risk factors for accelerated cognitive decline and dementia, and the data on this have gotten considerably stronger over the last several years. This one tends to get left off longevity lists because it does not fit neatly into a supplement stack or a lab test, but the biology is real. Chronic social isolation drives inflammation, disrupts sleep, and raises cortisol. Having purpose, having people, having reasons to engage with the world around you -- these are not soft variables. They are biological ones.

Hearing health

This might be the most underrated item on this list. Untreated hearing loss is one of the single largest modifiable risk factors for dementia, and almost nobody talks about it in longevity or brain health conversations. The leading hypothesis is that when the auditory system is underloaded, the brain compensates by diverting cognitive resources, which, over time, accelerates atrophy in regions involved in memory and processing. Get your hearing checked. If you need correction, get it. It is a low-cost intervention with surprisingly strong evidence behind it.

The Goal Is Not Immortality

Theoretically, with good choices across a lifetime, we might push healthy years well past 100. Some of the biology suggests it. But most of us have already crossed some bridges -- exposures, dietary patterns, stress loads, sleep deficits that have left marks we cannot fully erase.

The goal is not to undo that or to live forever. The goal is to compress the period of decline. Keep the years ahead as sharp, functional, and fully lived as possible. Push the hard part as close to the end as we can.

A Note for Those Already Living With Disease

If you are reading this and you are already dealing with a diagnosis, I want to speak directly to you for a moment.

Do not give up.

I mean that scientifically, not just emotionally. Precision medicine is not some distant fantasy. Clinical trials are happening right now across Alzheimer’s, Parkinson’s, cancer, cardiovascular disease, and many other conditions. The field is moving faster than it ever has. Things that were impossible ten years ago are standard of care today, and what seems out of reach today will not be out of reach for long.

The most important goal in the near term is limiting disease progression. Slowing the trajectory. Buying time while better interventions arrive. And there are real tools for this right now, not hypothetical ones. The lifestyle factors, the biomarkers, the sleep, the inflammation work—all of it becomes most urgent here, not least. It is not about reversing everything. It is about not ceding ground you do not have to cede.

Hope in this field is not wishful thinking. It is biologically grounded. The science behind cancer immunotherapy, early Alzheimer’s intervention, and neuroprotection in Parkinson’s is genuinely promising. I have watched this field long enough to know that breakthroughs come, and they come in ways nobody fully predicted.

So hang in there. Walk that extra mile. Not just for yourself but for the people around you, the family you want to stay present for, the moments you want to be sharp enough to actually experience. We are in this together, and that is not a platitude. It is the only way any of this actually works.

What is one change you are making right now for better healthspan? Drop it in the comments.

NeuroScope | Brain health, longevity science, and the neuroscience of everyday choices.

Buy me a coffee? ☕️😊

OFFICE KITCHEN · A TUESDAY MORNING

The coffee machine was brewing, a sweet aroma filling the air, when Nora walked in. Sarah was already there, leaning against the counter, scrolling her phone with the particular blankness of someone who isn’t really reading anything. Sarah felt her presence and looked up with a smile.

Nora looked different. Sarah had been trying not to notice for the past three months, and then trying not to say anything for the month after that. The blazer that used to pull at the shoulders, and the way Nora moved a little differently now. Easier, maybe.

Nora “You look tired.”

Sarah “I’m fine. Just didn’t sleep great.”

A pause. The coffee machine finished. Neither of them moved to take it.

Nora “How’s it going? The... you know.”

She didn’t say the word. She didn’t need to. They’d started the same medication within two weeks of each other. Sarah knew this because they’d talked about it, awkwardly, in this same kitchen, over terrible coffee, when the prescriptions were new, and the hope was still uncomplicated.

Sarah “It’s fine. It’s working. Slowly.”

It wasn’t working. Not really. She’d lost four pounds in fourteen weeks. Her doctor called it ‘modest progress.’ Sarah called it nothing, privately, at 11 pm on a Tuesday with her phone showing her before-and-after photos that were more or less identical.

Nora “Sarah.”

Sarah “I know what you’re going to say.”

Nora “I don’t think you do.”

Sarah “That I should give it more time. That everyone’s different. That I need to be patient.”

Nora shook her head slowly.

Nora “I was going to say that I read something last week that made me think of you. That maybe this isn’t what you think it is.”

Sarah looked up from her phone for the first time.

Sarah “What do you mean?”

Nora “I mean that it might not be anything you’re doing wrong. Or not doing. I mean it might be your brain.”

Sarah stared at her.

Sarah “What?”

The Numbers Behind the Headlines

Here’s the number that made the headlines: “14.9% weight loss with semaglutide.”

That’s the average weight loss from the STEP 1 trial published in the New England Journal of Medicine. It’s real, and it happened. This number put semaglutide on the map.

But averages hide things. Underneath that 14.9% is a range that runs from barely anything to well past 30%. Some people, fully compliant, and with a maximum dose, almost lost nothing after one whole year.

Tirzepatide’s trial with SURMOUNT-1 averaged 20.9 % weight loss. But it had the same pattern underneath. And in a 2025 study tracking 194 real patients in real clinics, only 58% had lost even 5% at six months. By 12 months, that had slipped to 49%.

Roughly half. Not because they quit. Not because they cheated. They were just not responding.

The Brain Regions That Decide Everything

Think of your brain as having two separate systems that these drugs need to reach.

The first is the hunger control center. Deep in the hypothalamus, a cluster of neurons monitors your energy levels and tells you when to eat and when to stop. GLP-1 receptors sit right in the middle of that system.

The second is the reward system. This is the part of your brain that makes food feel good. That lights up when you smell something delicious. That keeps nudging you toward the biscuit tin even when you’re not hungry. Scientists call it the mesolimbic pathway. Most people just call it craving.

When a GLP-1 drug works, it reaches both systems and turns the volume down. Less hunger signal from the hypothalamus. Less pull from the dopamine circuits. Together, that’s what patients describe as the food noise finally going quiet.

But here’s where individual biology starts to matter enormously. The drug can only engage receptors that are actually there. Some people have lower receptor density in these regions, whether from genetics, chronic inflammation, or years of metabolic stress. In those people, when the drug sends the signal, fewer antennae are listening. So fewer signals get through, and that means fewer changes.

It’s not that the drug isn’t working. It’s that the brain it’s trying to talk to is harder to reach.

The Wall the Drug Has to Cross

Here’s something that almost never makes it into the headlines about these medications.

Semaglutide is a large molecule. And large molecules cannot freely cross the blood-brain barrier, the protective layer that controls what gets in and out of the brain. So how does it get there at all?

It relies on three indirect routes.

The first is a set of small zones in the brain where the barrier is intentionally leaky, allowing certain things through. The second is a type of specialized cell that physically carries molecules from the bloodstream into the brain tissue, almost like a ferry service. The third is the vagus nerve, a long highway running from your gut directly up to your brainstem, which carries satiety signals from the body to the brain.

The catch is that all three of these routes work differently in different people.

Two people can have identical levels of the drug in their blood and completely different amounts actually reaching the brain circuits that drive weight loss. The drug got into the body just fine. The journey from there is where things diverge.

And for some people, that journey is compromised before they even start. Long-standing diabetes can damage the vagus nerve. Chronic gut inflammation can disrupt the signaling. Prior stomach surgery can alter the whole architecture. The drug is taken. It circulates. But it never quite arrives where it needs to be.

Why the Same Drug Hits Differently in Different Brains

Imagine two radios trying to pick up the same signal. One has a full set of antennas. The other has half. The signal being broadcast is identical. What gets received is completely different.

That is essentially what receptor density does in the brain.

GLP-1 receptors are not distributed equally across people. Some people have more of them in the regions that control hunger and reward. Some have fewer. And the number of receptors available in those regions directly determines how strongly the brain responds to the drug’s signal.

This is not something you can feel or observe from the outside. Two people can look identical on paper, same weight, same dose, same duration, and one of them has a hypothalamus that is densely populated with receptors ready to respond, while the other has significantly fewer. The drug arrives in both brains. But only one of them has enough antennas listening to pick up the full signal.

What drives these differences? A combination of genetics, chronic inflammation, metabolic history, and, in some cases, simply how the brain developed over time. It is not fixed permanently, but it is also not something you can change by trying harder.

When the Neuron Switches Itself Off

Even when the drug successfully reaches the right part of the brain and connects with a receptor, something unexpected can happen. The neuron switches itself off.

Here’s how … GLP-1 receptors sit on the surface of brain cells. When a drug like semaglutide binds to them repeatedly over time, the cell can respond by pulling those receptors inward, off the surface, out of reach. Like a shop that keeps getting too many deliveries and eventually closes the loading dock.

The drug is still there. The receptor is no longer available.

This may explain something a lot of patients recognize. An early response, some weight loss in the first few weeks, and then a plateau that never shifts no matter how long they stay on the medication.

There is one more layer. In people with chronic inflammation, which is extremely common in obesity, the brain’s own immune cells can intercept the drug’s signal before it ever reaches the appetite circuits. The drug is being used by the body. Just not for the reason you took it.

It May Be Written in Your DNA

In April 2026, a study published in Nature looked at nearly 28,000 people taking GLP-1 drugs. It was the largest study of its kind ever done on this question.

What they found was striking. Certain people carry a variation in the gene that builds the GLP-1 receptor itself. And that variation quietly predicts how much weight they will lose on these medications before they ever take the first dose.

It is not about mindset. It is not about metabolism in the way we usually talk about it. It is written into the DNA.

The same study found a separate gene variation linked to nausea as a side effect, but only in people taking tirzepatide specifically. Which tells you something important: different drugs interact with different genetic profiles in different ways. There is no one-size-fits-all here, and the science is only now beginning to map that out.

Earlier research had already pointed in this direction. A specific gene variant was found to influence how the gut responds to liraglutide and exenatide, changing how quickly the stomach empties and how strongly the brain receives the signal. Small differences in the receptor’s shape and function, all the way down at the molecular level, ripple upward into real, measurable differences in how much weight a person loses.

Your genes were part of this story the whole time.

What’s Being Built to Fix This

Scientists are no longer asking whether non-response is real. They know it is. The question now is what to do about it.

Several things are already in development.

New molecules are being engineered specifically to cross the blood-brain barrier more effectively than current drugs. One of them, NLY01, is designed to target the brain’s own immune cells and reduce the neuroinflammation that can block the signal. Oral versions of GLP-1 drugs, currently in Phase 3 trials, have smaller molecular structures that penetrate deeper into the brain than injected peptides. Newer drugs are also targeting multiple receptor types at once, hitting more pathways simultaneously rather than relying on a single route.

On the diagnostic side, researchers are working toward testing before prescribing. Gene profiling to identify who carries the receptor variants that predict response. Brain imaging to assess how active the reward circuits are before treatment starts. Eventually, a picture of your specific biology that helps a doctor choose the right drug for your brain rather than the average brain.

None of this is available in a clinic today. But the direction is clear.

The era of giving everyone the same drug and hoping for the best is ending. What’s coming next is personal.

SAME OFFICE KITCHEN · THREE WEEKS LATER

Sarah had done the reading. She’d gone down a rabbit hole at 11 pm on a Wednesday — PubMed, then a Nature paper, then a meta-analysis, then a thread someone had written that laid it all out in plain English. She’d sat with it for a while.

It didn’t fix anything. The scale still said what it said. Her clothes still fit the same way. But something had shifted in a way she was having trouble naming.

Nora was making coffee when Sarah came in.

Sarah “I read what you sent. And then I read seventeen other things.”

Nora “And?”

Sarah was quiet for a moment.

Sarah “I think I’ve been treating this like it was about trying harder. Like if I just … I don’t know. Was more disciplined or more patient or more something.”

Nora “And now?”

Sarah “Now I think it might be more complicated than that. And I don’t know if that makes me feel better or worse.”

Nora handed her a cup of coffee without being asked.

Nora “I think it makes you more right.”

Sarah laughed, briefly, against her will.

Sarah “I have an appointment with my doctor next week. I’m going to ask different questions this time.”

Nora “What kind of questions?”

Sarah “The kind that starts with ‘why’ instead of ‘how much longer.’”

The coffee machine started up again. Outside the window, the morning was doing its ordinary thing, indifferent to both of them.

It wasn’t a resolution. It was something smaller and more durable than that.

It was a place to start from.

Fuel my day? ☕️🚀😊

REFERENCES

1. Wilding JPH et al. (2021). STEP 1 Trial. N Engl J Med 384:989–1002. Link: https://www.nejm.org/doi/full/10.1056/NEJMoa2032183

2. Jastreboff AM et al. (2022). SURMOUNT-1 Trial. N Engl J Med 387:205–216. Link: https://www.nejm.org/doi/full/10.1056/NEJMoa2206038

3. Vozza A et al. (2025). Predictive factors of weight loss on GLP-1RAs. Front Endocrinol. Link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12507565/

4. Su et al. (2026). Genetic predictors of GLP-1 receptor agonist response. Nature. Link: https://www.nature.com/articles/s41586-026-10330-z

5. Cao X & Tong Q (2024). Hunting for Heroes. Obes Med. Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11741184/

6. Feng J & Jin T (2025). Brain access of GLP-1 and GLP-1R agonists. PMC. Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC12392083/

7. Dawson TM & Dawson VL (2025). From metabolism to mind. Neurotherapeutics. Johns Hopkins. Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC12491786/

8. Manolopoulos A et al. (2025). GLP-1RAs for neurological disorders meta-analysis. Alz Dement. Link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12739814/

9. van Bloemendaal L et al. (2014). GLP-1 receptor activation and reward-related brain areas. Diabetes. Link: https://pubmed.ncbi.nlm.nih.gov/25071023/

10. Eren-Yazicioglu CY et al. (2021). GLP-1 and reward system disorders. Front Behav Neurosci. Link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7848227/

What if a single injection could quiet the relentless craving for alcohol? Not by blocking the high, but by fixing the broken reward system underneath.

In August 2023, a paper in Nature Medicine did something remarkable. Researchers gave rhesus macaques unrestricted access to alcohol for months, enough for them to become genuinely addicted. Then they injected a single, harmless virus carrying one gene: the gene for GDNF, a protein the brain naturally makes but often doesn’t produce enough of.

The target was the reward centre of the brain.

Within weeks, the monkeys’ heavy drinking plummeted. Not because they were sedated or sick. Not because alcohol suddenly tasted bad. Their brains simply stopped craving it with the same intensity. The reward circuitry had been reset.

This wasn’t a sci-fi fantasy or a headline-grabbing exaggeration. It was careful, rigorous science. And while it doesn’t yet mean a human cure is around the corner, it reveals something profound about what the addicted brain is desperately trying, and failing, to do on its own.

Behind this headliner grabber is a protein made inside your body called “GDNF”.

What Is GDNF, and Why Does It Matter?

GDNF — Glial Cell Line-Derived Neurotrophic Factor — is a protein your brain produces naturally. It was first isolated and characterised in 1993 by Lin et al. at Synergen Inc. in a study published in Science.

The original paper showed it had a remarkable effect on the brain. It kept dopamine-producing neurons alive. Not just slightly better — dramatically better.

In the dish.

In rodents.

Then in primates.

Dopamine neurons are not ordinary brain cells.

They are small, highly specialised, and incredibly energy-hungry. Most of them live in a tiny region deep in the brain called the substantia nigra. These neurons do things almost no other cells in the body can do: they give us smooth, fluid movement, they create motivation, they generate that feeling of anticipation and “wanting.”

In short, they are the biological engine behind desire, drive, and coordinated action.

They are also the cells that die in Parkinson’s disease.

When they start to die, everything from Parkinson’s disease to aspects of addiction becomes much harder to treat.

By the time a Parkinson’s patient receives their diagnosis, roughly 50–80% of their dopamine neurons in the substantia nigra are already gone. The disease is slow, patient, and essentially invisible until the damage is catastrophic. GDNF was immediately recognised as potentially the most important neuroprotective substance ever discovered, because it appeared to be the signal those neurons needed to survive.

Thirty Years of Chasing GDNF — The Clinical Trial Saga

The story of GDNF in medicine is one of the most frustrating yet instructive tales in neuroscience. Decades of hope, setbacks, and hard lessons. We won’t dive into every chapter today, but there is one trial that stands out above the rest.

The 2019 Bristol Trial: When the Biology Worked But the Patients Didn’t Improve (seemingly)

In 2019, researchers in Bristol ran the most rigorous GDNF study ever conducted. It was the first properly blinded, placebo-controlled trial using direct delivery of the GDNF protein into the brain.

The results were genuinely paradoxical.

Brain scans showed clear biological success: the GDNF group had a 100% relative improvement in dopamine function compared to placebo. The imaging suggested that dopamine fibres were regrowing and becoming more active. At a cellular level, the treatment appeared to be working.

Yet when patients rated their actual movement and daily symptoms, there was no meaningful difference between the GDNF group and the placebo group.

The field has proposed several explanations, none definitively proven:

→ Too late

At diagnosis, 50–80% of dopamine neurons are already dead. You cannot restore function in neurons that no longer exist, regardless of what signal you provide to the survivors.

→ The Nurr1 problem

Kambey et al. (2021, Frontiers in Aging Neuroscience) identified that GDNF requires the Nurr1 transcription factor (NR4A2) to activate its downstream neuroprotective programmes. Nurr1 is substantially depleted in Parkinson’s patients. Without Nurr1, GDNF’s signal may reach the receptor but go largely unanswered.

→ Alpha-synuclein interference

The misfolded alpha-synuclein protein that defines Parkinson’s disease at the cellular level appears to disrupt GDNF’s intracellular signalling cascades. The receptor is activated; the cascade is blocked downstream.

→ Structural vs functional recovery

PET signal improvement reflects the structural activity of dopamine terminals. It does not guarantee that those terminals are functionally integrated into the motor circuits that produce the movements the UPDRS measures.

→ Delivery geometry

Even with CED (convection-enhanced delivery), achieving uniform GDNF distribution throughout the three-dimensional volume of the putamen is technically demanding. Point-source concentration effects likely mean large regions receive insufficient amounts.

→ My hypothesis

One reason the trial appeared to fail is that researchers set clinical symptoms as their primary goal — measuring whether patients felt and moved better in the short term. But the most meaningful changes happening inside the brain — the kind that slow disease progression over years and decades — don't necessarily show up in how someone feels during an 18-month trial. Biological markers that track what's actually changing at the disease level would have been a more appropriate measure of success. The biology was working. The goalposts may simply have been in the wrong place.

My Hypothesis - The Goalposts Were in the Wrong Place

Here’s something that has always struck me about the 2019 Bristol trial.

The researchers used a brain scan called F-DOPA PET to measure whether the treatment was working. And by that measure, it clearly was — the GDNF group showed double the improvement in dopamine activity compared to the placebo group. The neurons were responding. The biology was doing exactly what it was supposed to do.

But patients didn’t feel meaningfully better.

So either the treatment wasn’t working, or we were measuring the wrong thing.

I think it’s the second one.

An F-DOPA PET scan is essentially a photograph of dopamine activity in the brain. It tells you whether the machinery is running. What it can’t tell you is whether the machinery is actually connected to anything useful — whether those recovering neurons are properly wired back into the movement circuits that determine how a person walks, turns, and functions on a Tuesday afternoon. Structural recovery and functional recovery are not the same thing. The trial may have confirmed the first while missing the second entirely.

What makes this more interesting is that we now have better tools — tools that didn’t exist, or weren’t widely available, when the Whone trial was designed.

The first is called a Seed Amplification Assay, or SAA. In plain terms, it’s a test — done on a spinal fluid sample — that can detect the misfolded protein at the centre of Parkinson’s disease (alpha-synuclein) years before a person develops any symptoms. A major 2023 study in The Lancet Neurology, looking at over 1,100 patients, showed this test could identify Parkinson’s pathology with over 87% accuracy, often long before the classic tremor or movement problems appear. It has now been validated as a way to confirm the biological presence of Parkinson’s disease, independent of how severe the symptoms are.

The second is a skin biopsy — a small 3mm sample taken from the lower leg. Because the misfolded protein spreads through the body’s peripheral nervous system before it reaches the brain, it shows up in the tiny nerve fibres of the skin relatively early in the disease process. Studies published in JAMA Neurology and npj Parkinson’s Disease have shown this simple, minimally invasive test can detect Parkinson’s pathology with accuracy comparable to the spinal fluid test — and it’s far less uncomfortable to collect.

F-DOPA PET tells you whether dopamine terminals are growing back. The SAA and skin biopsy tell you whether the disease process itself is being slowed or reversed. That’s a fundamentally different question. And the more important one.

REGENERATE-PD, the major Phase II trial currently recruiting, does not use either of these tests as part of its design. That gap, in my view, is the single most important limitation in how the current generation of neurotrophic factor trials is being run. Their “Primary Clinical Endpoints” were too clinical. Switching to biological analysis and biomarkers will be more relevant.

The biology is working. We may simply not yet be asking the right question.

So What Does This Tell Us?

GDNF works. The biology is not in question. Thirty years of research, multiple human trials, and a post-mortem case study showing neurons still growing back 45 months after a single injection have confirmed that. The challenge has never been whether GDNF protects dopamine neurons. It clearly does. The challenge has always been getting it there.

That is the problem the field is now solving — through gene therapy, better patient selection, and smarter trial design. REGENERATE-PD will tell us in 2027 how close we are.

Then the supplement market moved in. Companies looking to profit from decades of legitimate research flooded the space with products making claims that the science simply does not support. It has muddied the waters and made it harder for people to know what is real. So let me take you through what actually works — for your health and your wallet.

This Isn’t Only a Parkinson’s Story

Here is something worth sitting with.

Parkinson’s disease gets most of the headlines in GDNF research because it is the most visible consequence of dopamine neuron loss. But the dopamine system does far more than control movement. It regulates motivation, mood, reward, and the brain’s resistance to addictive behaviour. GDNF is the survival signal for that entire system.

Which means that a well-functioning GDNF signalling system is not just relevant to people with a Parkinson’s diagnosis. It is relevant to anyone who wants to protect their brain from the gradual, largely invisible decline that precedes most neurodegenerative conditions — often by decades.

Declining dopamine neuron function has been linked to:

• Parkinson’s disease — the most direct consequence of dopamine neuron loss

• Alzheimer’s disease — dopaminergic and cholinergic systems interact; GDNF supports both

• Addiction and compulsive behaviour — low GDNF in the reward circuit is associated with dysregulated craving, as the 2023 monkey study showed

• Depression and low motivation — dopamine depletion underlies many of the drive and anhedonia symptoms of depression

• Accelerated brain ageing — dopamine neuron populations decline with age in everyone; the rate matters enormously

You don’t need a diagnosis to benefit from a brain that is better supported. Prevention, in neuroscience, almost always looks like nothing happening — which is exactly the point.

How Do You Actually Support This System?

Two routes: natural and clinical.

Natural options — what the evidence supports

None of the following raises GDNF directly. What they do is support the receptor system GDNF relies on, slow the protein damage that blocks it, or activate overlapping survival pathways.

☀️ Sunlight and Vitamin D3 — Vitamin D crosses the blood-brain barrier and directly regulates the expression of GDNF’s main receptor in dopamine neurons. Most people are deficient. Optimise to 40–60 ng/mL serum 25(OH)D.

🏃 Aerobic exercise — The most validated neurotrophic intervention available without a prescription. 49 randomised trials confirm large-effect increases in BDNF, GDNF’s closest functional relative. 150+ minutes per week.

😴 Sleep — The brain clears the misfolded alpha-synuclein protein — the one that blocks GDNF signalling — primarily during deep sleep. Seven to nine hours is not a lifestyle choice. It is neuroprotection.

🍄 Lion’s Mane mushroom — Contains compounds that cross the blood-brain barrier and stimulate nerve growth factor, a close relative of GDNF. Human trial evidence is limited but real. Worth considering alongside the above.

Here is the key thing to understand: Let’s say you manage to get GDNF into your circulatory system. When it reaches the brain, it encounters the brain’s blood barrier system. GDNF cannot cross the blood-brain barrier on its own. The brain has to make it internally, using its own cells and machinery. No supplement delivers GDNF to your neurons. No capsule replicates what gene therapy does. You cannot swallow your way to this outcome. Save your money.

Clinical options — where the field is heading

For those with a Parkinson’s diagnosis, or a family history, or confirmed early pathology through an SAA or skin biopsy test:

• AAV2-GDNF gene therapy — currently in Phase II trials (REGENERATE-PD). Not yet available outside a clinical trial. If the 2027 results are positive, this changes the landscape entirely.

• HER-096 — an engineered molecule designed to mimic GDNF’s protective partner protein (CDNF) and cross the blood-brain barrier via a simple subcutaneous injection. Phase 1b is ongoing in Parkinson’s patients. The first real attempt to solve the delivery problem without surgery.

What Comes Next — And Why the Future of Parkinson's Looks Nothing Like Its Past (My approach)

The research is pointing toward something important: no single intervention will be enough. The field is converging on a combination approach that looks like this.

First, neurotrophic support — using gene therapy to deliver GDNF or its relatives directly to threatened neurons, earlier in the disease process, before most of the damage is done.

Second, upstream protection — addressing the protein misfolding that starts the whole cascade, using a new class of compounds including MANF and CDNF, which work from inside the cell rather than outside it.

Third, clearing the toxic buildup — targeting alpha-synuclein directly to reduce the protein load that blocks GDNF from working in the first place.

Fourth, calming the immune response — the brain’s own immune cells become overactivated in neurodegeneration and make things worse. New drug candidates targeting this pathway are in active development.

And underpinning all of it — early intervention. Every one of these approaches works better the earlier it is applied. The biomarker tools to detect this disease before symptoms appear now exist. The window to act is opening. But only if people know it is there.

My perspective on where this needs to go

Here is something I think the field has been slow to fully confront.

It presents differently in different people. It progresses at different rates. It responds to treatments differently. Some patients have a predominantly motor presentation — the classic tremor and stiffness. Others have more cognitive involvement, more autonomic dysfunction, more psychiatric symptoms. Some decline rapidly. Others plateau for years. The underlying biology — which proteins are misfiring, which regions are affected first, which genetic variants are in play — varies enormously from person to person.

Yet clinical trials, including every GDNF trial conducted so far, have largely treated Parkinson’s as a single, uniform condition. Patients are enrolled based on a clinical diagnosis and a symptom score. They receive the same intervention. They are measured by the same scale. And then we wonder why the results are inconsistent.

My view is that the next generation of neurotrophic factor trials needs to be built around biological subtyping — not just clinical staging. Use the SAA and skin biopsy to confirm pathology. Use genetic profiling to identify which patients carry variants that affect GDNF signalling, Nurr1 expression, or alpha-synuclein aggregation rate. Use imaging not just to measure dopamine terminals but to characterise which circuits are still functionally intact and which are already gone.

The question should not be “does GDNF work in Parkinson’s patients?” The question should be “does GDNF work in this specific biological subtype of Parkinson’s, at this specific stage of pathology, delivered in this specific way?”

That is a harder trial to design and a harder trial to fund. But it is the right question. And I believe it is the one that will finally produce the answer thirty years of research has been building toward.

One size has never fit all in medicine. In a disease this heterogeneous, it was never going to fit here either.

The Bottom Line

Is your brain getting the support it needs?

That is not a question most people think to ask until something goes wrong. But the science covered in this article suggests the answer matters long before any diagnosis — and that the tools to understand it, and act on it, are further along than most people realise.

GDNF is one piece of a much larger picture. In the coming issues, we will go deeper into two of its closest partners — MANF and CDNF — proteins that work alongside GDNF in ways that may prove just as important, if not more so, for understanding how the brain protects itself and what happens when that protection starts to fail.

The biology is extraordinary. Science is moving fast. And for the first time in thirty years of research, the right questions are finally being asked.

Stay with me. It gets more interesting from here.

One size has never fit all in medicine. Diseases and the way we age are heterogeneous — we are all different, we develop conditions differently, and we respond to treatments differently. The interventions are coming.

Until then — lifestyle still matters today.

Fuel my day? ☕️🚀😊

If this was useful, share it with someone who needs to understand where neuroscience is heading. Every issue of The Neurotrophic Letter goes this deep — evidence-based, fully cited, and written for people who want to actually understand the science, not just hear about it.

Sources referenced in this issue:

• Ford et al. (2023) — Nature Medicine — GDNF gene therapy in NHP addiction model

• Whone et al. (2019) — Brain (Oxford) — Phase II intraputaminal GDNF RCT

• Kambey et al. (2021) — Frontiers in Aging Neuroscience — GDNF failure and Nurr1

• Heiss et al. (2024) — Movement Disorders — Persistent GDNF expression at 45 months

• Van Laar et al. (2025) — Movement Disorders — Phase 1b AAV2-GDNF AB-1005

• Pakarinen & Lindholm (2023) — Frontiers in Psychiatry — CDNF and MANF in PD

• Lv et al. (2020) — Translational Neurodegeneration — Vitamin D and GDNF

• REGENERATE-PD Phase II — ClinicalTrials.gov

• HER-096 / CDNF peptidomimetic Phase 1b — Herantis Pharma

It started with a phone call on a birthday.

Sonia dialled her mother Kamni to wish her a happy 52nd. It was a call she had made every year, easy, ordinary, the kind of call you make on autopilot. But something was wrong. She could not name it yet. Her mother’s voice was there, but something behind it was not. Something essential was already beginning to go.

Within weeks, Kamni was in the hospital. Within months, she was on life support. By the end of that year, she was dead, and no one, not a single doctor, had been able to tell her family what had happened. The disease that took her did not have a name yet, not for them. There was no diagnosis. There was only the absence of a woman who had been there, and then was not.

The autopsy came later. And it changed everything.

• • •

The report named it: a rare genetic prion disease, a subtype known as Fatal Familial Insomnia. It was caused by a single mutation in Kamni’s DNA. One letter, in one gene, out of three billion. A typo so small you could not see it. A typo that had been enough.

And then came the sentence that reordered Sonia’s universe: the mutation was hereditary. Sonia had a 50/50 chance of carrying it herself.

She was 27 years old. She had just graduated from Harvard Law School. She had just gotten married. She had her whole life arranged in front of her like a table set for a long dinner, and now someone was telling her the table might be on fire.

“Suddenly, there’s this tear in the universe, and my mom is being sucked through it. No one can tell us what’s wrong, but something is really, really wrong, and it is snowballing, and it is everything. I’m looking into her eyes, and they are these black holes, and I am begging her to come back. But it’s like I’m shouting into the void.”

That is how Sonia Vallabh described watching her mother die. Not in a private journal. On the stage of the 2024 TED Conference, in front of thousands of people, with the steadiness of someone who has learned, through years of deliberate and agonising effort, how to hold grief and science in the same hands without dropping either.

Because by the time she spoke those words, Sonia was no longer just a grieving daughter. She was not practising law anymore. She had changed her career, and now she is a scientist. Her own scientist. Racing, with everything she had, to cure her own disease before it could take her the way it took her mother.

WHAT IS FATAL FAMILIAL INSOMNIA?

Before we go further into Sonia’s story, you need to understand what she is up against.

Fatal Familial Insomnia is not simply a sleep disorder. It is one of the most devastating and least understood diseases in all of medicine, and almost nobody outside of a handful of research labs has heard of it.

Let us start with the word “prion.” A prion is not a virus. It is not a bacterium. It is not something that enters your body from the outside. It is a protein. Specifically, it is one of your own proteins, called PrP, that has folded itself into the wrong shape. And once that misfolding begins, it triggers a cascade: the misfolded protein encounters normal PrP and converts it too, like a whisper spreading through a crowded room until everyone is saying the wrong thing.

In Fatal Familial Insomnia, this process concentrates its damage in the thalamus, the small walnut-shaped structure deep in the centre of the brain that acts as the gatekeeper of consciousness. The thalamus governs the sleep-wake cycle. It regulates the autonomic nervous system. It filters sensory input and coordinates what reaches conscious awareness. When the thalamus begins to die, the results are catastrophic and unmistakable.

The clinical picture unfolds in stages. First comes the insomnia, not the ordinary sleeplessness of a stressful week, but a total inability to sleep, as though the switch has been permanently flipped to “awake.” The body cannot enter the deep restorative sleep cycles it needs to survive. Then come the autonomic disturbances: a racing heart, excessive sweating, fluctuating blood pressure, a body that no longer knows how to regulate itself. Then cognitive collapse. Hallucinations. Dementia. And finally, death. The average course from first symptom to the end is eighteen months.

There is no treatment. There is no cure. And because the disease is genetic, the tragedy does not end with one person. It moves through families, generation after generation, carried in a single letter of DNA.

Worldwide, only a few dozen families are known to carry this specific mutation. In the entire history of medical literature, fewer than 200 cases have ever been documented. It is, by almost any measure, one of the rarest diseases on earth.

And yet the lessons it holds for all of us are enormous.

A LAWYER BECOMES A SCIENTIST

Sonia and her husband Eric Minikel did something that almost no one does when confronted with a terminal genetic diagnosis. They did not grieve quietly and wait. They did not turn to unproven remedies. They did not hand their fate to someone else and hope.

They built a laboratory.

Within weeks of Sonia’s positive test result, both of them quit their careers, Sonia from law, Eric from transportation engineering. They took entry-level positions at research labs, doing work far beneath their education, pipetting samples and washing equipment alongside students half their age. They enrolled in night classes. They read scientific papers that they did not yet have the vocabulary to understand. They cold-called researchers around the world, introducing themselves simply as a family affected by prion disease who wanted to help.

Some scientists called them back. Most did not. They kept calling.

By 2014, both Sonia and Eric had enrolled in PhD programs in Biological and Biomedical Sciences at Harvard. They graduated together. They founded the Prion Alliance, a nonprofit dedicated to funding and accelerating therapeutic research. They now lead Prions@Broad, a research group at the Broad Institute of MIT and Harvard, working at the very edge of what science currently knows how to do.

Sonia has written about this transformation in the New England Journal of Medicine, one of the most prestigious medical journals in the world, describing the concept of the “patient-scientist.” The idea is straightforward: when you are both the researcher and the patient, when your own survival depends on the outcome of the experiment, you bring a quality of urgency and attention that no external motivation can replicate.

She describes their approach with a metaphor that has stayed with me since I first read it. “Driving at night in the fog. You can only see as far as your headlights, but you can make the whole trip that way.”

You do not need to see the end. You only need to see what is directly in front of you and keep moving.

THE WELLNESS EPIDEMIC

Here is where I need to speak to you directly, as someone who has spent years studying disease and trying to translate science for the people who need it most.

When a diagnosis is terrifying, when medicine says “we don’t know” or “we can’t cure this yet,” a space opens up. And into that space rush all manner of things. Some are well-meaning and simply misguided. Some are cynical and extraordinarily dangerous. All of them understand one thing very clearly:

Belle Gibson built one of Australia’s most successful wellness brands on the claim that she had healed her own brain cancer through diet and alternative therapies. She had not. There was no cancer. The diagnosis was fabricated. But tens of thousands of people trusted her, bought her cookbook, followed her protocols, and in some cases, genuinely diverted from medical treatment toward her methods. When the truth emerged, the damage had already been done.

Steve Jobs was diagnosed in 2003 with a pancreatic neuroendocrine tumour, one of the slowest-growing and most treatable forms of pancreatic cancer. His surgeon told him it was operable. His prognosis, had he acted immediately, was genuinely good. He did not act immediately. For nine months, he pursued dietary interventions, acupuncture, herbal remedies, and the counsel of a psychic. By the time he agreed to surgery, the cancer had spread. His own biographer described this delay as one of the few decisions in his life he genuinely regretted. He died in 2011.

I am not sharing these stories to judge anyone. Fear does extraordinary things to human reasoning. The desire to feel in control of something terrifying is not weakness; it is one of the most human responses imaginable. The juice cleanse, the supplement, the testimonial from someone who swears they healed themselves, these things feel like agency when medicine offers uncertainty. I understand the appeal completely.

But an agency built on false information is not an agency. It is the illusion of it. And the difference between the two can cost you your life.

This is exactly why I write about disease the way I do. Not to replace your doctor. Not to frighten you into paralysis. But to hand you the one thing that no influencer can sell and no algorithm can manufacture: the actual facts. The peer-reviewed, tested, challenged, sometimes revised, sometimes inconvenient facts. Because when you understand what a disease actually is, how it works at a cellular and molecular level, what the evidence for various treatments actually shows, you become someone who is very difficult to deceive.

You become your own best advocate. And that is the most powerful thing you can be.

WHERE THE SCIENCE STANDS

Back to Sonia. Because the science she and her team are building deserves your full attention.

The central logic of their therapeutic approach is elegant and compelling. Prion disease requires the prion protein. If you reduce the amount of PrP the brain produces, you reduce the fuel available for the disease to propagate. You do not chase the misfolded protein once it has spread. You reduce the supply before the cascade can begin.

In animal models, this strategy has shown remarkable results. Reducing PrP extended survival. In some experiments, it reversed symptoms that had already appeared. The science, while still evolving, pointed clearly in one direction.

In 2023, that direction became a clinical trial.

ION717 is an antisense oligonucleotide, a carefully designed molecule that silences the gene responsible for producing PrP. It is administered by lumbar puncture, directly into the cerebrospinal fluid that bathes the brain and spinal cord. In December 2023, the PrProfile Phase 1/2a trial opened enrollment. By December 2024, all 56 participants had been enrolled across sites globally. Preliminary data showed an encouraging safety and tolerability profile, and as of early 2026, the trial has reopened to test a higher dose level in the hope of achieving even deeper PrP reduction.

This is the first time in history that a drug designed to lower the protein that causes prion disease has been tested in living human beings.

Separately, Sonia’s own lab published work in 2024 demonstrating that a gene-editing approach could silence the prion gene by up to 90 % in mouse models. A 2025 study showed that altering the PrP-producing gene extended mouse lifespans by 52 %. In Italy, a long-running trial has been testing doxycycline as a preventive treatment in at-risk family members who carry the mutation but have not yet developed symptoms.

None of this is a cure. Not yet. But the trajectory is unlike anything this field has seen before.

NOT IF. WHEN.

Sonia Vallabh is now in her late thirties. She carries the mutation that killed her mother. She knows what that means clinically. She also knows, better than almost anyone alive, exactly what is being done about it and how close that work might be to mattering.

I think about what it takes to hold both of those things at once. The knowledge of what is coming and the absolute refusal to be passive in the face of it. The grief that never fully leaves and the daily discipline of transforming it into data, into experiments, into results.

She is not waiting to be saved. She is building the thing that might save her. And in doing so, she is building something that could save others who carry this mutation, and potentially lay the groundwork for treatments across the entire spectrum of prion diseases.

This is what I want you to take away from her story, and from this piece.

Not everyone can become a scientist. Not everyone can enrol in a PhD program, found a nonprofit, or run experiments at one of the world’s premier research institutions. That is not the point. The point is the posture. The refusal to hand your health entirely to someone else and hope for the best. The commitment to learning the real facts, even when they are frightening, even when they are uncertain, even when they do not come with the reassuring simplicity of a wellness influencer telling you that one simple change will fix everything.

Ask questions. Read widely. Get a second opinion. When a claim sounds miraculous, ask who funded the study. When a testimonial goes viral, ask what it is selling. When your doctor dismisses a symptom you know is real, push back. When the science is genuinely uncertain, sit with that uncertainty rather than filling it with something comfortable but false.

Your health belongs to you. Not to a brand. Not to an algorithm. Not to a doctor who has seven minutes and a waiting room full of patients. To you.

Sonia Vallabh looked at a death sentence written in her own DNA and said: not if. When.

You can say the same thing about your own health, in whatever form the fight takes. Not passively. Not with false hope. But with real knowledge, real questions, and the stubborn, beautiful refusal to stop fighting.

If you found this piece valuable, please share it with someone who needs it. All clinical trial information referenced here is publicly available through ClinicalTrials.gov. For more on Sonia Vallabh’s work, visit the Prion Alliance at prionalliance.org.

Fuel my day? ☕️🚀😊

It started with a single headline: “Eating one egg a week linked to 47% lower risk of Alzheimer’s.”

A lot of people dismissed it. Eggs have been vilified and rehabilitated so many times in the nutrition world that most of us have stopped paying attention. But I kept reading — past the headline, past the press release, and into the actual research. What I found was more compelling and more nuanced than any single headline can convey.

This is not a story about a magic food. It’s a story about brain chemistry, about decades of data collected from thousands of people across Finland, Spain, China, and the United States — and about a nutrient in egg yolks that your brain may genuinely need more of than you’re giving it.

Let’s go through it properly.

The Study That Started the Conversation

In 2024, researchers published findings from the Rush Memory and Aging Project — a long-running study out of Chicago that has been following older adults for decades, tracking their health, diet, and cognitive function, and — when they pass away — examining their brains under a microscope.

This particular analysis included 1,024 participants, with an average age of 81, followed for an average of 6.7 years. Researchers looked at whether egg consumption was associated with Alzheimer’s diagnoses. The result was striking.

But here’s where it gets genuinely interesting. The study didn’t stop at clinical diagnosis. Researchers also examined the actual brain tissue of 578 participants who had died during the follow-up period. And what they found in those brains matched what the clinical data suggested: regular egg eaters had measurably less amyloid plaque buildup and fewer tau tangles — the two proteins most closely associated with Alzheimer’s pathology.

This wasn’t people self-reporting that they felt sharper. This was the physical architecture of their brains, examined post-mortem, showing less damage.

The Nutrient Your Brain Is Probably Starving For

The Rush researchers didn’t just report an association — they investigated the mechanism. They found that dietary choline accounted for approximately 39% of the protective link between egg consumption and lower Alzheimer’s risk.

Choline is a nutrient that most people have never thought about. It doesn’t get the press coverage of omega-3s or vitamin D, but it may be one of the most important nutrients for brain health that we consistently fail to get enough of.

Here’s why it matters. Choline is the direct precursor to acetylcholine — the neurotransmitter most responsible for memory and learning. And Alzheimer’s disease is, in part, a disease of cholinergic destruction: it systematically degrades the neurons that produce and respond to acetylcholine.

A single large egg yolk contains approximately 147–150 mg of choline — roughly 25% of the recommended daily intake. Egg yolks are, by a significant margin, one of the richest dietary sources of choline available. Liver is the only common food that beats them.

The rest of the effect — the 61% not explained by choline alone — is attributed to the other compounds in egg yolks working in combination: omega-3 fatty acids (particularly DHA), lutein, zeaxanthin, vitamin B12, folate, and tryptophan.

This Isn’t Just One Finding

One study — even a well-designed one — is not a conclusion. But this is not one study. The egg-brain connection has been examined across multiple large populations on multiple continents, and the direction of the evidence is remarkably consistent.

1. Kuopio Ischaemic Heart Disease Risk Factor Study (Ylilauri et al., 2019) — Finland

2,497 men followed for 22 years. Highest phosphatidylcholine intake (mainly eggs) = 28% lower dementia risk. Best performance on memory and verbal tests.

2. Zhejiang Ageing and Health Cohort Study (Li et al., 2022) — China

9,028 adults aged 60+, followed 6 years. Eating 1–5 eggs/week is linked to up to 18% lower cognitive impairment risk. At 6+ eggs/week: no measurable benefit.

3. Rancho Bernardo Study (Kritz-Silverstein et al., 2024) — United States

1,515 older adults followed for 16 years. Higher egg intake in middle age is linked to better verbal episodic memory later in life. No cognitive harm in women.

4. Adventist Health Study-2 — United States (~40,000 participants)

Moderate egg consumption is associated with 17–27% lower Alzheimer’s incidence compared to rare or never consumers. Inverse dose-response trend confirmed.

Across these studies — different countries, different ethnic groups, different time horizons — the story is similar. Moderate egg consumption is consistently associated with better cognitive outcomes. There is no credible study showing that typical egg intake causes cognitive harm.

The Study That Said No — and What It Actually Tells Us

I want to be direct about the evidence that doesn’t fit the narrative, because ignoring inconvenient data is how nutrition misinformation spreads.

The EPIC-Spain Dementia Cohort — which followed 25,015 adults for over 21 years — found no overall association between egg consumption and Alzheimer’s risk in the general population.

But when researchers dug into subgroups, something revealing emerged. The protective signal from eggs only appeared in participants who had low adherence to the Mediterranean diet. In people who were already eating plenty of fish, olive oil, legumes, and vegetables, eggs showed no additional benefit.

This doesn’t mean eggs don’t matter. It means dietary context matters. And for the majority of people in Western countries who are not following a Mediterranean-style diet, eggs may be providing nutrients that aren’t coming from anywhere else.

The Bigger Picture: It’s Not Just the Egg

Here’s something the egg studies alone don’t fully capture, but that I think is essential context: what you eat eggs instead of may matter as much as the egg itself.

Alzheimer ’s-affected brains show profound disruption in glucose metabolism. Neurons lose the ability to efficiently convert sugar into energy — and as that process breaks down, they become more vulnerable to the toxic protein buildup that drives the disease. Researchers debate how much of this is a cause versus a consequence of neurodegeneration, but chronic high blood sugar and metabolic instability appear to accelerate the process regardless.

Chronic high blood sugar accelerates neuroinflammation. It damages the small blood vessels that supply the brain. It promotes the accumulation of the same toxic proteins — amyloid and tau — that the Rush study found in lower quantities in egg eaters’ brains.

When you eat eggs for breakfast, you typically aren’t eating a bowl of cereal, a pastry, or a stack of pancakes. The swap itself — more protein and fat, fewer refined carbohydrates — may be contributing to the brain benefit that researchers are attributing to the egg. It’s almost certainly not the whole story, but it’s likely part of it.

How Many Eggs Are We Actually Talking About?

The studies are fairly clear on the dose. You don’t need to eat eggs every single day to see the association. The threshold in the largest study — the Rush project — was more than one egg per week. That’s it.

The optimal range across studies appears to be somewhere between one and six eggs per week. The Zhejiang study found that at six or more eggs per week, the protective association disappeared. More is not necessarily better here. The sweet spot is moderate, consistent intake — not daily overloading.

For most people, two to four eggs per week — eaten with the yolk, not just the white — appears to represent the range where the most consistent benefits have been observed across multiple study populations.

What We Don’t Know Yet — And Why It Matters

I want to be precise about the limits of this evidence, because precision is what separates good science communication from health hype.

Every study I’ve described is observational. That means researchers tracked what people ate and what happened to their health over time — but they did not randomly assign people to eat or avoid eggs. People who eat eggs regularly may differ from people who don’t in dozens of ways that diet questionnaires can’t fully capture.

As of 2026, no large-scale randomized controlled trial has directly tested whether increasing egg consumption prevents Alzheimer’s disease. The authors of the Rush study, the Finnish study, and the others explicitly call for such trials. They are necessary before we can move from association to causation.

There is currently one registered clinical trial at ClinicalTrials.gov examining the effect of daily egg consumption on cognitive function in elderly adults (NCT01621646). Results from this and similar intervention studies will be critical to understanding whether the association we see in observational data translates into a real-world protective effect.

So Should You Be Eating Eggs?

If you don’t have a specific medical reason to limit eggs — a condition affecting cholesterol metabolism, a physician’s instruction, a dietary restriction — then the evidence currently provides no reason to avoid them and some reason to include them.

Not because one egg a week will save your brain. But because the nutrients in egg yolks — choline above all — are ones that most people in Western diets are consistently under-consuming, and those nutrients have clear, established roles in the biological systems that keep memory and cognition intact as we age.

The full body of research — 14 peer-reviewed studies, across five countries, covering more than 100,000 people — points in the same direction. It’s not proof. But it’s a signal worth taking seriously.

And it’s a reminder that the most powerful interventions for long-term brain health are often not exotic supplements or expensive treatments. Sometimes, there are things that have been sitting in your refrigerator the whole time.

Fuel my day? ☕️🚀😊

This article is for informational purposes only and does not constitute medical advice. Consult a healthcare provider for personalized dietary guidance.

Sources & Further Reading

1. Pan et al. (2024) — Rush Memory and Aging Project

2. Ylilauri et al. (2019) — Kuopio Choline & Dementia Study

3. Li et al. (2022) — Zhejiang Ageing & Health Cohort

4. Kritz-Silverstein et al. (2024) — Rancho Bernardo Study

5. EPIC-Spain Dementia Cohort (2022) — Frontiers in Nutrition

6. Zhou et al. (2025) — Lipid Variability & Dementia — Neurology

7. ClinicalTrials.gov — Egg Cognition Trial NCT01621646

8. NIH Choline Fact Sheet

The neurologist says the words. The patient and their family sit across the desk. Someone reaches for someone else’s hand.

They think they now know what they are dealing with.

They don’t. Not yet.

Here is a finding that most people in that room are never told: up to 25% of people who receive a clinical diagnosis of Parkinson’s disease are found, at post-mortem examination, to have had a different condition entirely.^[1] This is not a fringe result from a small or poorly designed study. It comes from a clinicopathological analysis of patients who had been diagnosed by experienced neurologists during life. Their charts said Parkinson’s disease. Their brains told a different story.

That does not mean the diagnosis is always wrong. It means the diagnosis is often incomplete.

There are dozens of distinct conditions that fall under the umbrella of what we loosely call ‘Parkinson’s.’ They share some surface features. But they have different biological causes, different rates of progression, different responses to medication, and different implications for treatment and planning.

This article maps those distinctions. Not to alarm, but because having the map is always better than not having it.

What Parkinson’s Actually Means

Most people use the terms interchangeably. Clinicians often do too, for practical reasons. But the distinction matters.

‘Parkinsonism’ is a symptom cluster — the observable features that characterise the condition: slowness of movement (bradykinesia), muscle rigidity, tremor, and problems with balance and posture. These are what a neurologist observes in the examination room.

‘Parkinson’s disease’ is one specific cause of Parkinsonism — the most common, but far from the only one. The same observable symptoms can have very different underlying causes, with very different implications for what happens next.

There are six major categories of conditions that produce Parkinsonism.^[2] The category you or your loved one is in shapes everything: how fast the disease progresses, whether standard medication works at all, whether you are eligible for specific clinical trials, and what the long-term trajectory is likely to look like.

Two people with ‘Parkinson’s disease’ written in their charts can be living with fundamentally different diseases. The label is the same. The biology is not.

The Six Categories — A Map

What follows is not an exhaustive clinical reference. It is an orientation — enough to understand where any given diagnosis sits and what questions that location raises.

Category A — Idiopathic Parkinson’s Disease (Classic PD)

This is what most people picture when they hear ‘Parkinson’s.’ Progressive loss of dopamine-producing neurons in a region of the brain called the substantia nigra. Characterised by a resting tremor, rigidity, and slowness. Responds well, at least initially, to levodopa — the primary medication used to replace the dopamine the brain is no longer producing.

Even within this category, there are three subtypes, and they are not equivalent. Tremor-dominant PD tends to progress more slowly and carries a better long-term prognosis. Postural instability and gait difficulty (PIGD) — where balance problems and walking changes dominate — tends to progress faster and carries a higher risk of falls and cognitive decline. A third mixed subtype sits between the two.

The word ‘idiopathic’ means the cause is not yet known. It does not mean untreatable. And it does not mean the prognosis is fixed — because even within this category, the biological picture beneath the surface varies significantly, particularly as copathology is taken into account.

Category B — Parkinson-Plus Syndromes

These are conditions that share the core motor features of Parkinson’s disease but involve additional systems failing, and they behave very differently from classic PD. They tend to progress faster, respond poorly to levodopa, and are frequently missed or misdiagnosed in early stages.

Multiple System Atrophy (MSA)

The defining feature of MSA is not the movement symptoms — it is what happens to the autonomic nervous system. Blood pressure drops dramatically on standing (orthostatic hypotension). Bladder function fails. Speech and swallowing deteriorate early. The resting tremor that is so common in classic PD is rare in MSA.^[3]

There are two subtypes: MSA-P, where Parkinsonian features dominate, and MSA-C, where cerebellar features — problems with coordination and balance — are more prominent. Levodopa response is poor or short-lived. Progression to severe disability typically occurs within 7 to 10 years of symptom onset.

Progressive Supranuclear Palsy (PSP)

The diagnostic clue in PSP is the eyes. People with PSP lose the ability to move their eyes voluntarily up and down — a sign called vertical supranuclear gaze palsy. They fall early and characteristically fall backward. Balance problems appear before the tremor that most people associate with Parkinson’s.

PSP is frequently misdiagnosed as Parkinson’s disease in its early stages and may not be recognised for years. Like MSA, it responds poorly to levodopa. It has several clinical subtypes — not all of them look like the classic description above — which compounds the diagnostic challenge.

Dementia with Lewy Bodies (DLB)

DLB sits on the same biological spectrum as Parkinson’s disease — both involve the accumulation of the protein alpha-synuclein — but its clinical presentation is distinct.^[4] In DLB, cognitive decline and dementia arrive before or alongside the motor symptoms, rather than years later as in classic PD. People with DLB often experience vivid, detailed visual hallucinations and fluctuating levels of alertness throughout the day. These are core diagnostic features, not side effects.

The distinction between DLB and Parkinson’s with dementia is largely a matter of timing: if significant cognitive decline comes within a year of motor symptoms, the diagnosis leans toward DLB. This distinction matters clinically because some medications commonly used in other dementias can cause severe adverse reactions in DLB.

Corticobasal Degeneration (CBD) and Corticobasal Syndrome (CBS)

CBD is the underlying pathology. CBS is the most common clinical presentation of that pathology, though CBD can also present in ways that look like PSP, frontotemporal dementia, or Alzheimer’s disease.

The hallmark of CBS is striking asymmetry — one side of the body is dramatically more affected than the other. The ‘alien limb’ phenomenon, where a hand or arm seems to move independently or feel as though it does not belong to the person, is a vivid and distressing feature. Cortical signs such as apraxia (difficulty performing purposeful movements despite intact motor function) are also characteristic. There is no meaningful levodopa response.

Category C — Genetic Parkinsonism

This is the most under-discussed category in patient conversations, and one of the most important.^[5] Genetic Parkinsonism is not a collection of rare family diseases that affect a handful of people worldwide. Some of the variants in this category are found in 4 to 20% of all Parkinson’s patients.

The key forms:

— LRRK2-associated PD is the most common identifiable genetic cause of Parkinson’s disease. It looks almost identical to idiopathic PD in clinical presentation — good levodopa response, typical motor features — but it is inherited, and it opens eligibility for LRRK2-specific clinical trials that are actively enrolling.

— GBA1 variants are the most common genetic risk factor for Parkinson’s disease, found in 4 to 20% of patients depending on the population studied. GBA1-associated PD tends to have an earlier age of onset, more prominent non-motor symptoms, including psychiatric features, and a somewhat faster cognitive trajectory than sporadic PD. Many patients carrying this variant have never been tested.

— PRKN and PINK1 mutations cause autosomal recessive Parkinson’s, typically with onset before the age of 50. These forms tend to progress slowly and respond well to levodopa. Lower-limb dystonia at onset is a characteristic feature of PRKN-associated PD.

— SNCA mutations — in the gene that encodes alpha-synuclein itself — are rare but tend to cause an aggressive, early-onset disease with a wide range of severity depending on the specific mutation.

The reason genetic status matters now, beyond individual prognostication, is that gene-targeted clinical trials are actively running. Your genetic profile determines which trials you are eligible for. Without testing, that eligibility is invisible.

Category D — Secondary Parkinsonism

These conditions have an identifiable external cause — and some of them are reversible. That alone makes this category critically important to consider, particularly in patients diagnosed at a younger age or in those whose presentation does not quite fit the classic picture.

— Drug-induced Parkinsonism is the second most common cause of Parkinsonism after PD itself. Antipsychotic medications, certain antiemetics, and some calcium channel blockers can all produce a Parkinsonian picture by blocking dopamine receptors. Symptoms may improve when the offending medication is stopped — though not always, and not always fully.

— Vascular Parkinsonism is caused by small strokes or white matter disease affecting the brain’s motor circuits. It tends to be bilateral and symmetrical, predominantly affecting the lower body — producing gait and balance problems rather than the arm tremor typical of classic PD. The gait pattern is different too: upright with a broad base, rather than stooped and shuffling.

— Normal Pressure Hydrocephalus produces a classic triad: gait disturbance, urinary incontinence, and cognitive changes. It is caused by excess fluid in the brain’s ventricles pressing on surrounding structures. It is treatable with a shunt. Missing it means years on the wrong treatment pathway.

If you or a loved one received a Parkinson’s diagnosis before the age of 50, secondary causes should be actively investigated and ruled out before the diagnosis is considered settled.

Category E — Rare Hereditary Neurodegenerative Conditions

A broader group of inherited neurodegenerative diseases that can produce Parkinsonism as part of their presentation. These include the Westphal variant of Huntington’s disease, certain spinocerebellar ataxias, neurodegeneration with brain iron accumulation, frontotemporal dementia with Parkinsonism linked to chromosome 17, Niemann-Pick disease type C, and others.

These are rarer than the categories above. But misdiagnosis means years on the wrong treatment pathway and, critically, missed opportunities for condition-specific support and counselling.

Category F — Copathology

This is not a separate disease category. It is a biological reality that reshapes how any of the above conditions behave — and it is almost never discussed in the context of an initial diagnosis.

The Part That Changes How You See Everything Else

Here is the finding that stops most people in their tracks when they first encounter it.

More than 90% of people with Parkinson’s disease show additional pathological processes in the brain at post-mortem examination.^[6] The disease almost never exists in isolation. It coexists with other conditions, other protein accumulations, other forms of neurodegeneration — and those coexisting pathologies directly influence how the disease behaves in life.

The three most clinically significant copathologies:

— Alzheimer’s pathology — amyloid plaques and tau tangles — is found in approximately 10% of non-demented Parkinson’s patients and up to 35% of those who develop Parkinson’s disease dementia. Its presence is a major driver of faster cognitive decline and earlier onset of dementia.

— Cerebrovascular disease — small strokes, white matter changes, hardening of the brain’s blood vessels — is present in approximately 44% of Parkinson’s cases. It tends to worsen gait and balance, and may drive the form of lower-body Parkinsonism that responds poorly to levodopa.

— TDP-43 pathology — the misfolded protein most commonly associated with ALS — is found in 7 to 19% of Parkinson’s brains. Its presence is linked to faster neurodegeneration and higher cognitive risk.

These pathologies do not simply add to each other. Research suggests that different misfolded proteins can cross-seed one another — meaning the presence of one can accelerate the spread of another through the brain. The interaction is not merely additive. It can be synergistic.

This is one of the central reasons why two people with the same Parkinson’s diagnosis can look and feel so different from each other. The label on the chart is the same. But the biology underneath it is not.

Why the Type You Have Changes Everything

At this point the question is reasonable: what do I actually do with this information?

The type of Parkinsonism matters in practical, consequential ways.

— Medication response: Levodopa is often transformative in classic idiopathic PD. In PSP and most Parkinson-plus syndromes, it provides little or no lasting benefit. Knowing the type prevents years on an ineffective treatment while the window for other interventions narrows.

— Prognosis: MSA typically progresses to severe disability within 7 to 10 years of symptom onset. Tremor-dominant idiopathic PD can remain stable for decades. These are not the same trajectory, and families deserve to plan accordingly.

— Trial eligibility: genetic variants like LRRK2 and GBA1 open specific trial pathways. Biomarker-based enrolment criteria are being used in an increasing number of trials. Without knowing your genetic status or your biological subtype, you cannot know what you are eligible for.

— Reversibility: Some secondary causes of Parkinsonism can be treated directly. Missing them means years on a management pathway for a disease you may not have.

— Planning and support: a family who knows their loved one has PSP rather than classic PD can prepare differently, seek condition-specific support, and make different decisions about care. Clarity, even when the news is hard, is almost always better than a vague label.

Why These Distinctions Get Missed

It is worth being honest about why these categories are not always clearly communicated at diagnosis.

Parkinson’s disease remains primarily a clinical diagnosis.^[2] There is no single definitive test available in routine practice that confirms it with certainty. And in the early stages, many atypical syndromes are virtually indistinguishable from classic idiopathic PD. The distinctive features of MSA, PSP, and CBD often only become clear as the disease evolves over months or years.

Movement disorder specialists — neurologists who have subspecialised in conditions like Parkinson’s — are specifically trained to identify these distinctions and to monitor for the red flags that suggest an atypical syndrome. A general neurology clinic may not have the same depth of focus.

The tools that exist to support diagnosis each have their limits. A DaTscan confirms that the dopamine system is affected, but cannot tell you which specific condition is causing it. MRI can show specific patterns that suggest PSP or MSA, but only in cases where those changes are already pronounced. The levodopa challenge — seeing whether symptoms respond to the medication — supports a diagnosis of classic PD but does not rule out other conditions definitively.

Newer tools are beginning to change this, and they will be covered in a future article in this series. For now, the practical point is this: the diagnostic picture often becomes clearer over time, not at the moment of diagnosis. Which is all the more reason to keep asking questions as the picture develops.

The Right Questions Change What Happens Next

A Parkinson’s diagnosis is not the end of uncertainty. It is the beginning of a more specific conversation — one that most patients are never told they are entitled to have.

The six categories above are not academic. They are maps to different treatment pathways, different research opportunities, and different conversations about the future. Knowing where you are on that map does not make the journey easier. But it means you can navigate it with more information than you had before.

The patients and families who ask the right questions at the right moments get more precise answers, more targeted treatment, and access to research that could matter enormously. That access should not depend on chance — on whether a particular neurologist happens to mention it.

It should start with knowing the questions exist.

Four questions worth raising at your next appointment with a movement disorder specialist:

1. Which specific type of Parkinsonism do I have — and how confident are you in that classification?

2. Have I been tested for genetic variants, particularly GBA1 and LRRK2?

3. Is there any secondary or reversible cause that should be actively ruled out in my case?

4. Based on my type and genetic profile, are there clinical trials I might currently be eligible for?

These are not aggressive questions. They are the right questions. A diagnosis is a starting point, not the whole answer.

Know the facts and take control of your health.

Fuel my day? ☕️🚀😊

References

1. Hughes AJ et al. Accuracy of clinical diagnosis of idiopathic Parkinson’s disease: a clinico-pathological study of 100 cases. Brain. 2002;125(4):861–879. https://academic.oup.com/brain/article/125/4/861/330396

2. Shin HW et al. Clinical aspects of the differential diagnosis of Parkinson’s disease and Parkinsonism. Journal of Clinical Neurology. 2022;18(3):259–270. https://pmc.ncbi.nlm.nih.gov/articles/PMC9163948/

3. Respondek G, Höglinger GU. The differential diagnosis and treatment of atypical parkinsonism. PMC. 2016. https://pmc.ncbi.nlm.nih.gov/articles/PMC4782269/

4. McKeith IG et al. Diagnosis and management of dementia with Lewy bodies: fourth consensus report of the DLB Consortium. Neurology. 2017;89(1):88–100. https://n.neurology.org/content/89/1/88

5. Billingsley KJ et al. The genetics of Parkinson’s disease and implications for clinical practice. PMC. 2021. https://pmc.ncbi.nlm.nih.gov/articles/PMC8304082/

6. Irwin DJ et al. Neuropathological and genetic correlates of survival and dementia onset in synucleinopathies. Lancet Neurology. 2017. https://pmc.ncbi.nlm.nih.gov/articles/PMC5940177/

7.Postuma RB et al. MDS clinical diagnostic criteria for Parkinson’s disease. Movement Disorders. 2015;30(12):1591–1601.https://movementdisorders.onlinelibrary.wiley.com/doi/10.1002/mds.26654

Here is something most people have never been told: milk and yogurt come from exactly the same source. Same cow, same raw ingredient. And yet, across more than two decades of population research, they suggest different patterns of association with one of the most feared brain diseases in the world — Parkinson’s disease.

This is not a fringe theory. It is a pattern that has been observed across large, independent studies involving hundreds of thousands of people — though, like most epidemiological findings, not without some inconsistency. And while it has been sitting in the scientific literature since the late 1990s, it has never quite broken through into public conversation. Now might be a good time for that to change.

What is Parkinson’s disease, and why does diet matter?

Parkinson’s disease is a progressive brain condition that affects roughly 1 in 100 people over the age of 60. It happens when the neurons that produce dopamine — the chemical messenger responsible for smooth, coordinated movement — begin to die. The result is the tremors, stiffness, and slowness of movement that most people associate with the disease.

There is no cure. Once those neurons are gone, they do not come back. That is why researchers have spent decades trying to understand what puts certain people at higher risk — and whether any of those risk factors are things we can actually do something about. Diet is one of the most promising places to look, because it is something people can change.

The milk signal — and why researchers take it seriously

The story starts in Hawaii in the 1990s, with one of the longest-running health studies ever conducted. In a group of more than 8,000 men followed over 30 years, researchers found that those who drank more than two glasses of milk per day had roughly double the Parkinson’s risk of those who drank none. That is a striking number — and it turned heads.

But here is why scientists take this seriously: the finding did not stay isolated. It kept showing up.

A 2024 systematic review pooled nine separate studies covering more than 634,000 people. It found that regular milk drinkers had about a 13% higher risk of developing Parkinson’s disease. Total dairy consumption was associated with about a 21% higher risk. The Hawaiian numbers represent one extreme of the range — most studies show a more modest effect. But the direction of the signal is often replicated across studies conducted in different countries, by different researchers, with different populations — though not universally observed.

That repeated appearance across independent cohorts is what makes epidemiologists take notice — even when individual studies vary in effect size.

Why would milk affect the brain? Four theories

Researchers have proposed four biological explanations for the milk-Parkinson’s link — and none of them are mutually exclusive. All four may be operating at once.

• Your brain’s natural shield gets lowered. Milk consumption reduces levels of uric acid in the blood. Uric acid sounds like a bad thing — it causes gout — but in the brain, it acts as a protective antioxidant. Multiple large studies have found that people with higher uric acid levels have lower Parkinson’s risk. Milk may quietly deplete this natural protection.

• Inflammation. Some research has linked regular milk consumption to modest increases in markers of systemic inflammation in certain individuals — though the overall literature here is mixed, with some studies showing neutral or even anti-inflammatory effects. Where it does occur, this matters because neuroinflammation — inflammation in the brain — is increasingly understood not just as a side effect of Parkinson’s, but as a driver of it. Activated immune cells called microglia can accelerate dopamine neuron destruction when chronically inflamed.

• The calcium-iron connection. High calcium intake from dairy may increase how much iron the brain absorbs. This is the most speculative of the four theories, but excess iron in specific brain regions is consistently found in Parkinson’s patients. The mechanism is biologically plausible — not yet proven.

• Pesticide hitchhikers. Certain organochlorine pesticides — agricultural chemicals widely used in the mid-20th century — have historically been detected in dairy fat and proposed as a potential contributor. Researchers have found these compounds in the brains of Parkinson’s patients at autopsy. Modern dairy exposure levels are considerably lower than in earlier decades, and a direct causal link via milk has not been established — but the biological pathway remains a plausible hypothesis worth noting.

None of these is the single confirmed cause. All four are biologically coherent, and all four point in the same direction. Together, they give the epidemiological association a mechanistic backbone that pure statistics alone cannot provide.

Then comes yogurt — and the plot twist

If milk is often associated with higher Parkinson’s risk, you might expect all dairy to tell the same story. Some studies suggest it does not. When researchers looked specifically at fermented dairy — yogurt, kefir — some found a different or weaker association with Parkinson’s risk, with several meta-analyses reporting a trend toward lower risk. This signal is less established and more variable than the milk finding, but it is consistent enough to be biologically interesting.

Why might fermented dairy behave differently? Several hypotheses have been proposed. Fermentation alters the protein and fat structure of milk in ways that may change how it interacts with gut bacteria. The live bacteria introduced during fermentation — strains like Lactobacillus and Bifidobacterium — produce compounds called short-chain fatty acids, which have been shown to reduce inflammation in the brain. Fermented dairy also appears to have a somewhat different effect on protective uric acid than raw milk. These are plausible mechanisms — not yet proven pathways.

MILK

• Often replicated higher risk signal

• Lowers protective uric acid

• Historically proposed pesticide pathway

• May influence inflammatory markers in some

• 13–21% higher risk in meta-analysis

YOGURT & FERMENTED DAIRY

• Trend toward lower risk in some studies

• Different effect on uric acid than milk

• Probiotics produce anti-inflammatory SCFAs

• Gut bacteria link biologically plausible

• • Emerging signal — less established than milk risk

The gut-brain connection you may not have heard about

One of the most significant developments in Parkinson’s research over the last decade has nothing to do with the brain directly. It concerns the gut.

Many Parkinson’s patients report digestive problems — particularly constipation — years or even decades before any movement symptoms appear. Researchers have found that the protein at the heart of Parkinson’s disease, called alpha-synuclein, may actually begin to misfold in the gut before it ever reaches the brain, traveling upward via the vagus nerve. This is still an active area of research, but it has fundamentally changed how scientists think about where Parkinson’s begins.

Multiple studies have found that the gut microbiome of Parkinson’s patients looks distinctly different from that of healthy people. Among the bacterial groups most often reported as altered are Lactobacillus and Bifidobacterium — the same genera delivered by fermented dairy products like yogurt and kefir. Results vary across studies, and the microbiome is complex, but the directional overlap between this research and the fermented dairy findings is worth noting.

The inflammation thread that ties it all together

If there is one concept that connects everything in this article — the milk risk, the yogurt benefit, and the gut-brain research — it is inflammation.

For a long time, Parkinson’s was understood primarily as a disease of dopamine neuron loss. Scientists now increasingly see it as a disease in which the brain’s immune system — specifically cells called microglia — becomes chronically activated. When something triggers those microglia to keep firing, they release inflammatory signals that accelerate the destruction of the very neurons Parkinson’s patients are trying to protect.

This matters because the two sides of the dairy picture sit on opposite ends of the inflammation dial.

Some research has linked regular milk consumption to modest increases in systemic inflammatory markers — compounds like C-reactive protein — in certain individuals. The overall literature here is mixed, and some studies show neutral or anti-inflammatory effects. But where this influence does occur, it is worth considering in the context of a disease where chronic low-grade neuroinflammation plays a central role.

Fermented dairy may work in a different direction. The short-chain fatty acids (SCFAs) produced by probiotic bacteria during fermentation — particularly butyrate — have been shown to reduce microglial activation and calm neuroinflammation in animal models. Butyrate can cross the blood-brain barrier and directly dampen the inflammatory signaling that drives dopamine neuron death. Human data here is still emerging, but the mechanistic picture is compelling.

This is why the inflammation angle is not just an add-on to the dairy-Parkinson’s story. It is arguably the mechanism that makes the whole picture coherent: gut health, microbial balance, neuroinflammation, and dopamine neuron survival are all part of the same biological chain.

What the science does — and does not — tell us

This is the part where it is important to be careful with words.

What it does NOT show

• Milk causes Parkinson’s disease

• Yogurt prevents Parkinson’s disease

• Any individual guarantee of risk or protection

• That other lifestyle factors can be ignored

What it DOES show

• An often-replicated population-level signal

• Biologically plausible mechanisms for both associations

• Inflammation as a connecting thread across the evidence

• Enough signal to inform thoughtful dietary choices

These are population-level patterns. Epidemiology tells us about groups — not about what will happen to any specific person. Plenty of lifelong milk drinkers never develop Parkinson’s. Plenty of people who never touch dairy do. Genetics, environmental exposures, and many other lifestyle factors all play a role. What the dairy research offers is something more modest but still meaningful: a consistent signal with a plausible biological explanation, replicated across independent populations.

What you can actually do with this information

Nobody is suggesting you pour your milk down the drain. But if you are thinking seriously about long-term brain health — especially if you have a family history of Parkinson’s disease — this research offers a few reasonable, low-risk takeaways.

1. Consider swapping some of your milk intake for fermented dairy — yogurt or kefir with live cultures. This is consistent with both the Parkinson’s data and the gut-brain and neuroinflammation research, and carries no meaningful downside.

2. If you do drink milk regularly, organic full-fat options may reduce exposure to the pesticide residues that several researchers have flagged as part of the mechanism. This is a modest step, not a guarantee.

3. Look at your overall dietary pattern. A Mediterranean-style diet — rich in vegetables, olive oil, fish, and fermented foods — has independently been associated with later onset of Parkinson’s disease in peer-reviewed research. Its anti-inflammatory profile is increasingly seen as central to that benefit. The fermented dairy piece fits naturally into that wider picture.

These are informed choices, not medical prescriptions. They are the kind of low-cost, evidence-supported adjustments that are worth knowing about — and that your doctor is statistically unlikely to bring up at your next check-up, because the research has not yet filtered through to clinical guidelines.

“The milk-Parkinson’s story has been in the literature for over 20 years. Most people have never heard of it — not because the evidence is weak, but because it is complicated.”

Same source. Different processing. Potentially different effects on inflammation, gut health, and the neurons your brain depends on. That is exactly the kind of nuance that gets lost in health headlines — and exactly why this research is worth knowing.

Fuel my day? ☕️🚀😊

Key sources

• Ascherio A et al., Ann Neurol 2007

• Systematic review & meta-analysis, Public Health 2026 (9 studies, 634,000+ participants)

• Hong CT et al., Nutrients 2020

• Sampson TR et al., Cell 2016

• Metcalfe-Roach A et al., Mov Disord 2021

• Corrigan FM et al., J Toxicol Environ Health 2000

• Ascherio A & Schwarzschild MA, Lancet Neurol 2016

This article is for informational purposes only and does not constitute medical advice. Consult your neurologist or physician before making significant dietary changes, particularly if you or a family member has been diagnosed

By the time a tremor appears, Parkinson’s disease has often been in the body for ten to twenty years.

That is not a metaphor. It is what science now shows.

The neurodegeneration, the protein accumulation, the slow loss of dopamine neurons in the substantia nigra — all of it starts long before anyone notices anything is wrong. Before the handshake. Before the gait changes. Before anyone walks into a clinic.

What we call ‘early Parkinson’s’ is not actually early at all.

This is not a minor clinical footnote. It changes how Parkinson’s should be detected, staged, and treated. And it is the reason why, in January 2024, a global team of researchers published a paper in The Lancet Neurology that rewrites how we think about Parkinson’s staging from the ground up.

Most patients and caregivers have never heard of it. What we call “early Parkinson’s” is not actually early at all.

There is also something most patients are never told at diagnosis.

It is the most common one on the Parkinsonism spectrum. But not the only one. And which cause is driving those symptoms matters enormously for what happens next.

This article explains what changed, why it matters, and what it means in practice.

The System Doctors Still Use — And What It Cannot Do

For almost 60 years, Parkinson’s disease has been staged using the Hoehn and Yahr scale.

Published in 1967^[4] — before levodopa was even a standard treatment — it was built on one principle: describe what a neurologist can observe in a clinical examination.

It gives five stages:

— Stage 1: symptoms on one side of the body only

— Stage 2: both sides affected, but balance intact

— Stage 3: balance impairment begins

— Stage 4: significant disability, though walking remains possible

— Stage 5: wheelchair or bed-bound, unable to stand without assistance

It is simple. It is practical. It is still used in clinics around the world, and for good reason — it gives a shared language for describing functional decline.

But it has a fundamental limitation that has never been fixed.

It only measures what you can see.

The Hoehn and Yahr scale tells you how someone presents in the room. It does not tell you what is happening in the brain. It cannot tell you how fast someone will progress. Two patients can both sit at Stage 2 and have completely different futures — one stable for a decade, another deteriorating within two years — and the scale provides no way to distinguish between them.

That is not a flaw in implementation. It is a structural limitation. The system was designed before we understood the underlying biology well enough to incorporate it. For 57 years, that was the best we had.

It is no longer the best we have.

The Phase That Neither System Captures

Before we get to what is new, there is something the conversation around Parkinson’s staging has historically missed almost entirely.

The disease does not begin with a tremor.

Research now shows that the prodromal phase of Parkinson’s — the period of neurological change before any motor symptom appears — can last up to twenty years.^[6] During this time, Lewy body pathology is already spreading. Dopamine neurons are already being lost. The biological clock has already started.

The earliest warning signs appear far from the motor system:

— REM sleep behaviour disorder: people physically act out their dreams, sometimes violently. This is the single strongest individual predictor — approximately 80% of people with this condition will eventually develop a synucleinopathy such as Parkinson’s, Lewy body dementia, or multiple system atrophy.

— Loss of smell: affects up to 90% of Parkinson’s patients at the time of motor diagnosis, and is thought to begin years earlier due to Lewy pathology in the olfactory bulb.

— Constipation: in some patient cohorts, reported on average 16 to 20 years before the first motor symptoms appear.

— Depression and anxiety: linked to early changes in serotonergic and noradrenergic systems, often emerging years before the classic motor presentation.

None of these symptoms alone is diagnostic. Constipation is common. So is anxiety. So is disrupted sleep. But in combination, they carry a real signal.^[7] Research from the Honolulu-Asia Aging Study found that having two or more of these prodromal markers was associated with a fourfold increase in Parkinson’s incidence compared to having just one.

There is also a compelling biological explanation for why these non-motor symptoms come first. According to the Braak staging hypothesis, Lewy pathology may begin in the gut and the olfactory system before it reaches the substantia nigra. The disease does not start in the movement centres of the brain. It starts at the edges and travels inward.

This matters enormously for staging. If Parkinson’s can be detected in this prodromal phase, the entire window for intervention expands dramatically. Instead of treating a disease that has been running for two decades, we could potentially act years earlier.

That is exactly what the new staging framework is designed to enable.

A New Framework: Biology Before Symptoms

In January 2024, Tanya Simuni and colleagues published a landmark paper in The Lancet Neurology proposing a fundamental redefinition of what Parkinson’s disease is and how it should be staged.^[1]

The core argument is straightforward, though its implications are profound:

Stop defining Parkinson’s by what you can observe. Define it by what is happening biologically.

The new system — called the Neuronal Synuclein Disease Integrated Staging System, or NSD-ISS — is built around two biological anchors that together define the disease at its roots:

— S: the presence of abnormal, misfolded alpha-synuclein, the protein that accumulates in Parkinson’s and forms the Lewy bodies that characterize the disease. This is detected using a new test called the Seed Amplification Assay.

— D: dysfunction in the dopaminergic system, detectable on imaging such as a DaTscan, indicating that dopamine neurons are already being lost.

When both of these markers are present, neuronal synuclein disease is biologically confirmed — regardless of whether any symptom has appeared.

That is the shift. Parkinson’s is no longer a clinical diagnosis alone. It becomes something that can be identified and staged at a biological level, earlier, and more precisely than anything we have had before.

The system has been validated in over 1,741 patients across three major international research studies — PPMI, PASADENA, and SPARK — giving it real-world grounding, not just theoretical weight.

The Seven Stages — What They Actually Mean

The NSD-ISS runs from Stage 0 to Stage 6. The critical thing to understand before reading the table is this:

The first half of the disease — Stages 0 through 2 — is completely invisible to the old Hoehn and Yahr system.

Those stages exist before any symptom appears. They are biologically real but clinically silent. Under the current clinical framework, they do not exist. Under the new framework, they are the most important window we have.

The highlighted row is important. Stage 3 — where symptoms are clear enough to diagnose in a clinic — is where the vast majority of patients enter the system today. What the NSD-ISS reveals is that by Stage 3, the biology has already passed through at least two earlier stages, potentially spanning years.

And for the first time, this staging system comes with prognostic data.

In a validation study published in npj Parkinson’s Disease in 2024^[2], researchers tracked over 1,700 patients and found:

— Those at Stage 2B at baseline: median 8.3 years to a clinically meaningful disease milestone

— Those at Stage 3 at baseline: median 5.9 years

— Those at Stage 4 at baseline: median 2.4 years

These are median figures from a research cohort — not a guarantee for any individual. Disease trajectories vary. But this is the first time a staging system has provided any biological basis for a timeline conversation. For patients who have been told their disease is unpredictable, that is significant.

The Test That Makes It Possible

The NSD-ISS depends on the ability to detect misfolded alpha-synuclein in a living person. That became possible with the development of the Seed Amplification Assay, or SAA.^[3]

The SAA works by taking a sample of cerebrospinal fluid — via a spinal tap — and amplifying even tiny quantities of misfolded alpha-synuclein until they become detectable. It is highly sensitive: in the PPMI study, it correctly identified alpha-synuclein pathology in 93% of people with sporadic Parkinson’s.

The analogy that captures its significance best is what amyloid PET imaging and blood-based amyloid tests did for Alzheimer’s disease. They moved that field from a symptom-based diagnosis to a biology-based one. Clinical trials could then enrol patients earlier, and treatment development followed. The same transition is now beginning in Parkinson’s.

There are limitations. The test currently requires a spinal tap. Results are binary — positive or negative — not quantitative. It cannot tell you when symptoms will start or how severe they will be. Work is ongoing to develop less invasive versions using blood or skin samples.

But the principle is established. The biology can be detected. And that changes what is possible.

Why This Changes Clinical Trials — And Why That Matters to You

The most immediate practical impact of the new staging framework is on clinical trial design. And that matters to patients more than it might sound.

Most current Parkinson’s treatments manage symptoms. What the field has not yet achieved is a disease-modifying treatment — something that slows or stops the underlying neurodegeneration.

One major reason for that failure is timing. Disease-modifying drugs almost certainly work best before significant neuronal loss has occurred. But under the old H&Y framework, clinical trials could only enrol people with visible symptoms — by which point a substantial proportion of dopamine neurons are already gone.

The NSD-ISS changes the enrolment window.

With biological staging, trials can now enrol participants at Stage 1 — people with confirmed alpha-synuclein pathology and zero clinical symptoms. The disease is present. The neurons are still largely intact. That is the window where intervention has the greatest chance of working.

This is not theoretical. Trials using biomarker-defined enrolment criteria are actively running right now. The same logical and structural shift that eventually produced the first approved disease-modifying treatments for Alzheimer’s — built on biological staging of that disease — is now being applied to Parkinson’s.

How long that takes is unknown. But the infrastructure is being built.

What This System Cannot Do Yet

Important: the NSD-ISS is currently a research tool. It is not used in routine clinical practice.

If you see a neurologist today, you will still be staged using the Hoehn and Yahr scale.

That does not mean the new framework is irrelevant to you — but it does mean your expectations should be calibrated.

The Movement Disorder Society, the leading international professional body for Parkinson’s specialists, has explicitly stated that clinical application of the NSD-ISS is premature at this stage.^[5]

There are genuine reasons for caution. The SAA test requires a spinal tap. The results are not yet quantifiable — they tell you whether misfolded alpha-synuclein is present, not how much. A positive result does not tell you when symptoms will start or how severe they will be. Larger, longer longitudinal studies are still needed to fully validate the system across different populations.

None of that changes the direction of travel. The NSD-ISS is already shaping every major Parkinson’s trial being designed. Research tools become clinical tools. The pipeline from laboratory to clinic is active.

The science is moving. The clinical application is following. Talk to your neurologist. They can order these tests for you.

The Floor Has Shifted

For decades, the conversation about Parkinson’s staging began with the tre

mor. That was the starting line.

It is not the starting line anymore.

The disease begins years before the tremor. The biology can now be detected before the tremor. And a staging system has been built that starts where the disease starts, not where the symptoms start.

That shift — from observable symptoms to measurable biology — is the same shift that unlocked progress in other neurodegenerative diseases. It takes time to move from research framework to clinical practice. But the direction is clear, the tools are real, and the trials are running.

For the first time, we are beginning to map Parkinson’s disease before it becomes visible. That is where the real shift is.

The staging system is catching up to the biology. Once it does, everything else — diagnosis, trial design, treatment timing — follows with it.

If you or a loved one has Parkinson’s disease, these are worth raising at your next appointment with a movement disorder specialist:

1. Am I eligible for any clinical trials that use biomarker-based enrolment criteria?

2. Has my genetic status been tested — specifically GBA1, LRRK2, or SNCA variants?

3. Is there any reason to investigate prodromal markers in my case, given my symptom history?

These are not aggressive questions. They are the right questions. A diagnosis is a starting point, not the whole answer.

Next article, we will talk about the different faces of Parkinson’s.

Fuel my day? ☕️🚀😊

References

1. Simuni T et al. A biological definition of neuronal α-synuclein disease: towards an integrated staging system for research. Lancet Neurology. 2024;23(2):178–190. https://www.thelancet.com/journals/laneur/article/PIIS1474-4422(23)00405-2/abstract

2. Dam T et al. Neuronal alpha-synuclein disease integrated staging system performance in PPMI, PASADENA, and SPARK baseline cohorts. npj Parkinson’s Disease. 2024;10:178. https://www.nature.com/articles/s41531-024-00789-w

3. Siderowf A et al. Assessment of heterogeneity among participants in the PPMI cohort using alpha-synuclein seed amplification. Lancet Neurology. 2023;22:407–417. https://www.thelancet.com/journals/laneur/article/PIIS1474-4422(23)00109-7/abstract

4. Hoehn MM, Yahr MD. Parkinsonism: onset, progression and mortality. Neurology. 1967;17(5):427–442. https://pubmed.ncbi.nlm.nih.gov/6067254/

5. Cardoso F et al. A statement of the MDS on biological definition, staging, and classification of Parkinson’s disease. Movement Disorders. 2024. https://www.movementdisorders.org/Moving-Along/2024-issue-1/Statement-of-the-MDS-on-Biological-Definition-Staging-and-Classification-of-PD.htm

6. Goldman JG, Postuma R. Premotor and non-motor features of Parkinson’s disease. Current Opinion in Neurology. 2014. https://pmc.ncbi.nlm.nih.gov/articles/PMC4181670/

7. Savica R et al. Prevalence of prodromal symptoms of Parkinson’s disease in the late middle-aged population. PMC. 2022. https://pmc.ncbi.nlm.nih.gov/articles/PMC9108586/

Dietary Interventions Are Starting to Work — But Only If You Do Them Right

Over the past decade, something quiet has been happening in neurology and neuroscience. Researchers have begun testing whether what we eat might influence how diseases like Parkinson’s, epilepsy, and other neurological conditions progress. Mediterranean diets. Low-carbohydrate approaches. Intermittent fasting. Ketogenic protocols. The scientific evidence for dietary intervention in disease management is real, it’s growing, and it’s being largely ignored by the public — partly because the public has fundamentally misunderstood what these diets actually are.

Here’s the core problem: scientists design these diets with extraordinary precision. They measure macronutrient ratios down to the gram. They understand how fat, protein, and carbohydrates activate different metabolic pathways inside the body. They run trials testing the exact formulation they’ve devised. The results are often significant.

Then the general public, social media influencers, fitness coaches, and wellness entrepreneurs take that diet, decide they like it better with more protein or fewer fats or slightly higher carbs, and they rebrand it as the same intervention. It is not.

The gap between what science tests and what people actually do is where most dietary interventions fail. And nowhere is this gap more consequential than with the ketogenic diet.

What Parkinson’s Really Is — And Where Medicine Falls Short

Parkinson’s disease affects more than 8.5 million people worldwide. Most people picture the tremors — the shaking hands that have become the public face of the condition. But ask most patients what actually destroys their quality of life, and the answer is rarely the tremors.

It’s the bone-deep fatigue that sleep doesn’t fix.

The chronic pain with no clear source.

The brain fog that makes a simple conversation feel like wading through mud.

The bladder problems that make leaving the house an exercise in anxiety.

The depression that settles in and doesn’t lift.

These are called non-motor symptoms, and they are in many ways the cruellest part of the disease. Parkinson’s is, at its core, a progressive condition that gradually destroys the neurons responsible for producing dopamine — the brain chemical that controls movement. The gold-standard drug, levodopa, replenishes dopamine and works reasonably well for motor symptoms, especially early on. But it has a hard limit: for the invisible suffering described above, it offers little. These symptoms are often poorly controlled with existing treatments — not because medicine hasn’t tried, but because the tools available are inconsistent, partial, and frequently limited by side effects.

They also worsen as the disease progresses, with no reliable solution on the horizon.

So when clinical trials start showing that a specific way of eating might help with exactly these symptoms — significantly, in a matter of weeks — that’s worth understanding properly. And understanding it properly means first clearing up one of the most widespread misconceptions in modern nutrition.

The Inflammation Connection: A Fire That Drugs Don’t Put Out

Here is something that rarely features in conversations about Parkinson’s: the disease is not just about neurons dying. It is also driven, in part, by chronic inflammation in the brain.

In a healthy brain, the immune system is tightly regulated — it responds to threats and then stands down. In Parkinson’s disease, that system gets stuck in the “on” position. There is an ongoing, low-grade inflammatory state that contributes to further neuron damage. Standard Parkinson’s treatments do not address this inflammatory process at all.

This is where a properly formulated ketogenic diet becomes scientifically interesting. When the body enters genuine ketosis, the liver produces a molecule called beta-hydroxybutyrate — let’s call it BHB.

BHB is not just a fuel source. Research shows it actively blocks a major inflammatory pathway in the body known to be overactive in Parkinson’s patients — specifically the NLRP3 inflammasome, part of the brain’s internal alarm system.

In plain English: BHB helps turn down the alarm that’s stuck in the “on” position. For a brain already under inflammatory siege, this is potentially significant — and it helps explain why the diet may be doing something beyond simply providing alternative fuel. A 2025 review published in Pharmacological Reports documented these mechanisms in detail, describing how ketones reduce neuroinflammation and oxidative stress in Parkinson ’s-related brain changes.

Also, a major 2022 study shows that Beta-hydroxybutyrate (BHB) reduces neuroinflammation and neuron damage in Parkinson’s disease models by blocking the NLRP3 inflammasome and preventing inflammatory cell death (pyroptosis).

Another review added more context and argues that beta-hydroxybutyrate (BHB) can modulate microglia (the brain’s immune cells) and reduce neuroinflammation, potentially slowing processes involved in neurodegenerative diseases like Parkinson’s.

And the field is growing, and Clinical trials are coming out. I highlight some successful ones later in this article.

But there are mixed and failed ones too. I can talk about those if you are interested in the Substack chat.

Parkinson’s is not one disease. Different pathologies may respond differently. The ketogenic diet (KD) has been studied almost exclusively in idiopathic (sporadic) Parkinson’s disease, which accounts for the vast majority (~85–90%) of PD cases. These are the typical cases without a clear single-gene cause or known external trigger like toxins or vascular damage.

It is also worth noting that the causal role of inflammation in Parkinson’s is still being studied — we know it is present and likely contributing, but the full picture remains incomplete. What is established is the mechanism by which BHB interacts with inflammatory pathways. Whether that translates to meaningful clinical benefit in humans is what the trials are beginning to show.

This is why talking to a neurologist and scientists is relevant if you plan to incorporate a ketogenic diet into your symptom management.

The “Gym Keto” Problem — And Why It Matters

Scroll through social media and you’ll find “keto” everywhere. But the version being sold — high protein, moderate fat, low-ish carbs, marketed for fat loss and muscle gain — is not a ketogenic diet. Metabolically, it is a low-carb, high-protein diet. And that distinction is not semantic. It is biological.

Here is why. When you eat more protein than your body needs for its immediate functions, the liver can convert some of that excess into glucose through a process called gluconeogenesis. You end up quietly manufacturing sugar in the background while believing you’re in ketosis.

Importantly, gluconeogenesis is demand-driven rather than a simple on/off switch. High protein doesn’t automatically cancel ketosis — but it can significantly blunt ketone production, making it much harder to reach and sustain the metabolic state the clinical research was actually measuring. A half-achieved ketosis is not the same as the state tested in these trials.

For healthy people chasing fat loss, the high-protein, low-carb version may deliver some results. Fine. But for people with Parkinson’s disease or epilepsy, where the specific metabolic state of ketosis is therapeutically meaningful, this version doesn’t reliably work — and for reasons we’ll come to shortly, it may actively work against the goal.

Another reason why Gym Keto is bad - The Medication Angle Almost Nobody Is Talking About

A 2024 clinical trial published in BMC Neurology found an intriguing early signal: after just two days on a ketogenic diet, the trial detected trends in levodopa metabolite levels suggesting potentially improved drug delivery. This was a feasibility study and the findings were not statistically definitive — but the direction is worth noting.

The likely explanation: protein in the diet competes directly with levodopa for entry into the brain. Reduce dietary protein — as a properly formulated keto diet does — and there is less competition, meaning more of the drug may reach its target. Same dose, potentially better delivery.

This doesn’t mean keto replaces medication. It means the right dietary approach might make existing medication work more effectively. That is a significant hypothesis, even if it needs larger trials to confirm.

Read the study: Choi et al. 2024 — BMC Neurology

Can the Real Ketogenic Diet Please Stand Up?

So what does clinical keto — the version actually tested in research — look like?

What the clinical trials actually used:

• Fat: 70–80% of daily calories

• Protein: moderate — 15 to 18%

• Carbohydrates: under 20 grams per day

What most people doing “keto” actually eat:

• High protein — often 150g or more per day

• Moderate fat

• Lowish carbohydrates

The reason protein is kept moderate in clinical keto is precise: excess protein triggers gluconeogenesis, which generates glucose, which prevents the body from fully switching to ketone metabolism. If glucose remains available, the body simply won’t commit to running on ketones. That switch is the mechanism. Without it, you’re not doing what these studies tested.

Think of it like trying to run a car on a different fuel — but you keep topping it up with the old one. The engine never fully converts. The results from the clinical trials we’re about to discuss do not apply to someone eating high protein and calling it keto.

Why This Matters More for Neurological Patients

For the general population, failing to achieve proper ketosis is mostly a missed opportunity — you simply don’t get the metabolic state you were aiming for. But for people with Parkinson’s disease or epilepsy, the stakes are meaningfully higher.

For Parkinson’s patients:

Remember the inflammatory fire we discussed? Chronically elevated blood sugar is associated with increased inflammatory signalling — hyperglycaemia activates pathways known to worsen neuroinflammation. A diet claiming to be ketogenic that quietly generates glucose through gluconeogenesis may therefore be working against the very goal it set out to achieve. Additionally, glucose fluctuations interact poorly with levodopa absorption in ways that are still being studied, potentially destabilising medication effectiveness in unpredictable ways.

For epilepsy patients:

The ketogenic diet has been used as a therapeutic intervention for epilepsy for nearly a century, particularly in children with drug-resistant seizures. It works — but only in genuine, sustained ketosis. Hidden gluconeogenesis from excess protein means hidden glucose in the bloodstream, which means the metabolic state that suppresses seizure activity is never fully achieved. For someone depending on ketosis to control seizures, that gap is not just ineffective — it could be dangerous.

This is why the composition of the diet is not a minor detail. It is the entire mechanism.

Clinical trials: What Real Keto Did for Parkinson’s Patients

In 2018, a team of researchers in New Zealand published a randomised controlled trial in the journal Movement Disorders — one of the first rigorous head-to-head comparisons of a genuine ketogenic diet against a low-fat diet in Parkinson’s patients.

The setup: 47 Parkinson’s patients. Eight weeks. Two groups.

• Group one: a genuinely ketogenic diet — 70–75% fat, around 18% protein, under 4% carbohydrates

• Group two: a low-fat, higher-carbohydrate diet

The results for non-motor symptoms:

• Keto group: 41% improvement

• Low-fat group: 11% improvement

The biggest gains in the keto group were in exactly the symptoms medication struggles most to address: urinary problems, pain, fatigue, daytime sleepiness, and cognitive impairment. The ketogenic group showed substantially greater improvement overall, and notably, no patient in the keto group got worse on non-motor scores.

Both groups improved in motor symptoms too, though the difference between them was less dramatic. It was the non-motor picture — the invisible suffering — where the ketogenic diet showed its clearest advantage.

Read the study: Phillips et al. 2018 — Movement Disorders

The 2026 Confirmation: Early Evidence Is Accumulating

In January 2026, a new pilot trial published in Frontiers in Neuroscience added a second data point. Twenty-seven Parkinson’s patients followed a ketogenic diet for twelve weeks. The results showed statistically significant improvements in both motor and non-motor symptoms.

Two independent research teams. Two different countries. Twelve weeks instead of eight. The same directional result. As a pilot study without a large control comparator, this adds to early-stage evidence rather than confirming the finding outright — but two independent teams pointing the same direction is a meaningful signal worth watching.

Read the study: Luo et al. 2026 — Frontiers in Neuroscience

More studies below.

Worster et al. (2025) – Mixed-methods feasibility study (modified low-dairy KD)

Norwitz et al. (2020) – Ketone ester drink (exogenous BHB) for exercise performance

And here is a repeat of what I said earlier because this is important.

There are successful clinical trials. But there are mixed and failed ones too. I can talk about those if you are interested in the Substack chat.

Parkinson’s is not one disease. Different pathologies may respond differently. The ketogenic diet (KD) has been studied almost exclusively in idiopathic (sporadic) Parkinson’s disease, which accounts for the vast majority (~85–90%) of PD cases. These are the typical cases without a clear single-gene cause or known external trigger like toxins or vascular damage.

It is also worth noting that the causal role of inflammation in Parkinson’s is still being studied — we know it is present and likely contributing, but the full picture remains incomplete. What is established is the mechanism by which BHB interacts with inflammatory pathways. Whether that translates to meaningful clinical benefit in humans is what the trials are beginning to show.

This is why talking to a neurologist and scientists is relevant if you plan to incorporate a ketogenic diet into your symptom management.

Why the Parkinson’s Brain Responds to Ketones

The biology here is genuinely fascinating, and it doesn’t require a science degree to follow.

Parkinson’s disease damages the tiny energy-generating factories inside brain cells — structures called mitochondria. Specifically, it breaks a critical step in the energy-making chain that glucose depends on to fuel neurons. When that step is broken, glucose can no longer efficiently power the affected brain cells. They begin to starve.

Ketones — the fuel produced during genuine ketosis — bypass that broken step entirely. They use a different route into the cell’s energy system, one that the disease has not damaged. So ketones can reach and fuel neurons that glucose can no longer adequately supply.

On top of the fuel-switching effect, BHB also:

• Reduces neuroinflammation — directly relevant given the inflammatory component of Parkinson’s

• Decreases oxidative stress, a process that damages neurons

• Supports the production of BDNF, a protein that helps neurons survive and function

These mechanisms are documented in preclinical research and animal models, with some human evidence emerging. They are biologically plausible and scientifically grounded — though the full picture in human Parkinson’s disease is still being established. The 2025 Pharmacological Reports review covers them in detail.

Why You Should Not Try This Without a Doctor

This needs to be stated clearly, because the internet makes everything sound simple and accessible. Ketogenic dieting for Parkinson’s disease is not a lifestyle experiment to run solo. Here is why:

Levodopa timing is complicated.

Levodopa is typically taken with specific timing relative to meals and protein intake. Change your diet significantly without adjusting your medication schedule and you risk either reducing drug effectiveness or creating unpredictable fluctuations throughout the day. This is not something to manage without a neurologist’s guidance.

Liver stress is real — and the evidence is mixed.

A high-fat ketogenic diet puts significant demands on the liver, which must simultaneously produce ketones and process medications. For an elderly Parkinson’s patient taking levodopa, MAO inhibitors, antidepressants, or other drugs, that is a genuine concern. Evidence on liver risk is mixed: some studies show keto can improve certain liver conditions, while others flag potential lipid and fatty liver changes depending on diet composition and duration. What is clear is that all the trials showing benefit ran for only 8 to 12 weeks — nobody knows what happens at six months or two years.

Proper monitoring is required.

Blood ketone levels, liver function, lipid panels — these need tracking during any ketogenic intervention, especially in an older population with existing health conditions. A clinical keto protocol involves regular medical oversight and ideally input from a dietitian experienced with therapeutic ketogenic diets. Doing it alone based on a YouTube video is not the same intervention that produced the results in these trials.

Long-term effects remain genuinely unknown.

All the promising trials are 8 to 12 weeks. We simply do not have data beyond that in Parkinson’s populations. The long-term metabolic effects of sustained strict keto remain open questions. Any use of this diet as part of Parkinson’s management should involve periodic review with a medical team — not a permanent, unsupervised lifestyle adoption.

A medically supervised ketogenic diet shows promising short-term improvements in non-motor Parkinson’s symptoms, supported by small trials and biologically plausible mechanisms involving energy metabolism and inflammation. Evidence remains early, limited in size, with no proof of disease modification and no long-term safety data. Benefits appear sensitive to diet composition — and the real keto tested in trials is not the high-protein version that dominates social media.

What the Evidence Actually Says

What is supported by current research:

• Non-motor symptom improvement: consistent finding across multiple independent trials

• Anti-inflammatory mechanism: documented in preclinical research, biologically plausible in humans

• Potential improvement in levodopa effectiveness: early signal, needs larger trials

• Safe for 8–12 weeks in supervised clinical settings

What is not yet supported:

• No trial has shown it slows or modifies disease progression

• No long-term data beyond 12 weeks exists in Parkinson’s populations

• It does not replace medication under any circumstances

• “Gym keto” — high-protein, low-carb eating — is not the same intervention and may worsen the inflammatory picture

For families and patients living with the daily invisible burden of Parkinson’s — the fatigue, the pain, the fog — knowing this research exists is genuinely valuable. The evidence for a properly formulated ketogenic diet as a supervised adjunct therapy is stronger than most people and many neurologists currently realise.

But the keyword is properly formulated. The real ketogenic diet — the one the science is actually testing — is not the high-protein, low-carb approach that fills social media. It is a precise, medically supervised intervention with a specific composition, a defined timeframe, and ongoing monitoring.

If you or someone you love is living with Parkinson’s and you’re interested in this evidence, the conversation to have is with your neurologist. Show them the studies. Ask about supervised options. And if they haven’t heard of this research yet — now you can bring it to the table.

Sources

• Phillips et al. 2018 — Movement Disorders (RCT)

• Luo et al. 2026 — Frontiers in Neuroscience

• Choi et al. 2024 — BMC Neurology (MCT-KD trial)

• Pokora et al. 2025 — Pharmacological Reports (mechanisms review)

• KIM Trial 2025 — ClinicalTrials.gov NCT05469997

• WHO Parkinson’s Disease Fact Sheet

Disclaimer: This article is for informational and educational purposes only. It does not constitute medical advice. The studies referenced are real peer-reviewed research, but dietary interventions for neurological conditions carry real risks and must be undertaken only under medical supervision. Always consult your neurologist or treating physician before making any changes to your diet, especially if you are taking levodopa, MAO inhibitors, or any other Parkinson’s medications.

Fuel my work ☕️🚀😊

The Shocking Prescription for a Disease Defined by Losing Movement

Parkinson’s disease is defined by the loss of movement.

Tremor. Rigidity. Slowness.
The gradual breakdown of the brain’s ability to control the body.

And yet.

The most compelling non-drug intervention modern neuroscience has identified is not rest.
It is not protection.
It is not slowing down.

Not gentle stretching. Not a casual walk.
Sustained, demanding effort. The kind that pushes the heart rate to around 80% of its maximum and keeps it there.

This is not intuitive. It is, in many ways, the opposite of what most people — including many physicians — would instinctively prescribe for a neurodegenerative disease characterized by the inability to move. And that counterintuitive reality is exactly why it matters.

The Gap No One Likes Talking About: Nothing Stops Parkinson’s Progression… Yet

Here is something the mainstream conversation around Parkinson’s disease rarely states plainly:

No drug has ever been definitively proven to slow the progression of Parkinson’s disease in humans. Not a single one.

Current therapies — including Levodopa, dopamine agonists, and MAO-B inhibitors — can control symptoms, sometimes with striking effectiveness. However, they have not been definitively shown to alter the underlying disease process or halt neurodegeneration. The loss of neurons continues. Disease progression remains largely unchanged. These treatments preserve function and extend quality of life, but they do not alter the disorder's trajectory. There are newer, more promising therapies emerging. However, they are in clinical trials and will be available 5-10 years down the line.

This is the gap that makes what is happening in exercise science right now genuinely significant.

Exercise — specifically high-intensity aerobic exercise — is currently the only intervention with a credible signal of disease modification in clinical trials. Not just symptom improvement. Actual evidence, from rigorously designed randomized controlled trials show that the underlying progression of the disease may be affected.

If the evidence holds, it would represent the first time a non-pharmacological intervention has been shown to alter the course of Parkinson’s disease itself. That is not a small claim. That is a potential turning point.

What Parkinson’s Really Does to the Brain (It’s Not Just Tremors)

Parkinson’s disease is, at its core, a problem of dying brain cells. Over time, the cells that produce dopamine — a chemical essential for smooth, automatic movement — gradually break down and disappear. As this occurs, movement becomes slower, stiffer, and harder to initiate. The body does not forget how to move. It loses the chemistry that makes movement feel effortless.

At the same time, a protein in the brain begins to misfold and clump inside cells. These clumps spread over time, disrupting not only movement but also thinking, mood, sleep, and basic body functions. This is why Parkinson’s eventually extends far beyond a movement disorder.

Parkinson’s is not a single, uniform condition. It exists on a spectrum, with people experiencing different symptoms, progression rates, and responses to treatment. It also sits within a broader group of conditions known as Parkinsonism, which share similar movement features but arise from different underlying causes, including distinct neurodegenerative diseases, genetic variants, and drug- or toxin-induced syndromes.

The disease unfolds in stages, from early subtle changes to more advanced impairment affecting movement, cognition, and daily functioning. These stages reflect fundamentally different biological realities, which is why what works in one stage may not work in another. The interventions discussed here apply primarily to early- to mid-stage Parkinson’s, when biological systems remain more responsive, and the evidence for meaningful impact is strongest.

Importantly, by the time a diagnosis is made, a substantial portion of dopamine-producing neurons has already been lost, often estimated at 50–80%. The disease has typically been progressing silently for years, long before the first motor symptoms appear. This means diagnosis is not the beginning of Parkinson’s disease, but the point at which its effects become visible.

This has major implications for prevention and treatment. If preserving neurons is the goal, the critical window lies before symptoms emerge. This shifts the central question from what to do after diagnosis to what can be done years earlier, before the disease is recognized. Exercise science is beginning to address this question, with evidence pointing toward sustained, high-intensity physical activity as a key intervention both before and after diagnosis. These findings are not just about symptom management, but about whether movement itself can influence the underlying disease process.

The Evidence: What the Clinical Trials Actually Show — Ranked by Strength

Below is a summary of the major randomized controlled trials and meta-analyses in exercise and Parkinson’s disease, organized by the strength and nature of their signal. This is not an exhaustive list of all exercise research — it is the evidence that matters most for understanding what works, what partially works, and what does not appear to modify the disease.

Tier 1 — Strongest Evidence: Disease-Modifying Signal

SPARX Phase II and SPARX3 Phase III Clinical Trials

SPARX Phase II (JAMA Neurology, 2018)
The SPARX trial enrolled individuals with newly diagnosed, untreated Parkinson’s disease and randomized them to high-intensity treadmill exercise (80–85% of maximum heart rate), moderate-intensity exercise (60–65% HRmax), or a stretching control group. Participants trained for 30 minutes per session, several times per week, over a six-month period.

The results showed that the high-intensity group did not worsen over the study period, while the moderate-intensity and control groups showed declines in motor function. This produced an important signal that exercise intensity, not just exercise in general, may influence the trajectory of disease progression. The key variable appeared not to be simply engaging in activity, but reaching a sufficient physiological threshold.

SPARX3 Phase III (Northwestern University, ~370 participants)
SPARX3 was built on this Phase II signal and designed to test the question at scale: whether high-intensity aerobic exercise provides greater benefit than moderate-intensity exercise in slowing Parkinson’s progression. The trial enrolls approximately 370 participants across multiple sites and compares high-intensity versus moderate-intensity treadmill training, both delivered at 30 minutes per session, four times per week over 18 months. High-intensity targets roughly 80–85% of maximum heart rate, while moderate-intensity targets approximately 60–65%.

Unlike Phase II, SPARX3 does not include a non-exercise control group. Instead, it directly evaluates the relative efficacy of different exercise intensities. The study is still ongoing, and final results have not yet been published.

CYCLE-II — Cleveland Clinic (Multi-site RCT)

RCT = Randomized Controlled Trial

In this rigorously designed multi-site trial of 256 individuals with mild-to-moderate Parkinson’s disease, participants were randomized to home-based stationary cycling or usual care. The aerobic exercise group showed a motor progression rate of 0.2 points per year on the standard Parkinson’s scale (MDS-UPDRS III). The usual care group progressed at 3.9 points per year. That difference — p<0.0001 — is one of the most striking results in the field.

High-Cadence Cycling (Ridgel / Cleveland Clinic group)

This line of work introduced a mechanistically different concept: motor-assisted cycling at 75–90 RPM — approximately 30% above a patient’s voluntary cadence — produces significant improvement in bradykinesia (slowness) and rigidity. In controlled studies, the motor-assisted group showed a 13–14% improvement in motor scores, compared with approximately 1% in controls. The mechanism here appears distinct from cardiovascular intensity: the high-cadence rhythmic input may directly entrain the motor circuits of the basal ganglia, rather than acting through aerobic or metabolic pathways.

Tier 2 — Moderate Evidence: Consistent Functional Improvement

• PRET-PD (Progressive Resistance Exercise Training): A two-year randomized trial of weight training in Parkinson’s patients showed sustained improvement in motor scores, particularly in the off-medication state. Strength gains were durable. The disease-modifying signal is weaker than high-intensity aerobic exercise, but the functional benefit — including real-world strength and independence — is meaningful and consistently reproducible.

• LSVT BIG (Amplitude Training): A randomized trial of high-amplitude movement training — emphasizing large, exaggerated movements to counter the characteristic smallness of Parkinsonian movement — showed significant motor score improvement versus home exercise. This is now widely used clinically but remains underappreciated in the public conversation.

• Park-in-Shape (Home Aerobic Cycling): A well-designed RCT testing home-based aerobic cycling with virtual coaching and gamification elements. Improved motor scores with notably high adherence — the gamification component is genuinely relevant to the real-world challenge of sustained exercise in this population.

• HIIT (High-Intensity Interval Training) — 2023 Meta-Analysis: A meta-analysis aggregating 15 randomized controlled trials and 654 participants found that HIIT is feasible and safe in mild-to-moderate Parkinson’s disease, with improvements in VO2 peak, motor symptoms, fatigue, and BDNF levels. An important nuance: HIIT (short bursts with rest) and the sustained continuous high-intensity protocols in SPARX are physiologically different. The sustained model currently has the stronger evidence base, but HIIT is promising and more accessible for many patients.

Tier 3 — Functional Benefit, No Disease-Modification Signal

• Tai Chi (Li et al., New England Journal of Medicine, 2012): 195 patients randomized to Tai Chi, resistance training, or stretching over 24 weeks. Tai Chi significantly reduced falls and improved postural stability vs. stretching, with benefits sustained at 3-month follow-up. Published in the NEJM, it carries enormous credibility weight. The honest characterization: best evidence for falls reduction and balance. Not disease-modifying.

• Dance / Tango Therapy (Duncan & Earhart, multiple RCTs): Rhythm-based dance produced a 28.7% reduction in motor symptoms off-medication across multiple trials, with improvements in gait and cognition. Mechanistically interesting — it combines rhythmic input, coordination demands, and cognitive engagement simultaneously. Strong for functional quality of life. Not progression-slowing.

• Standard treadmill training at moderate intensity: Consistently improves gait speed and mobility. Does not produce a progression-slowing signal. This matters because it shows the benefit is not from treadmill exercise per se — it is from the intensity at which it is performed.

No Meaningful Signal

• Low-intensity exercise programs: Improve general well-being. No functional motor benefit or disease-modification signal in controlled trials.

• Stretching-only programs: Consistently used as the control arm in major trials. No meaningful benefit beyond basic mobility maintenance. This does not make stretching useless — it is simply not an active intervention against the disease process.

The One Variable That Separates What Works From What Doesn’t

When you look across every trial in this field — from SPARX to CYCLE-II to HIIT to forced cycling — one pattern emerges with unusual consistency:

It is not which exercise you do. It is how hard you do it. Every intervention with a credible disease-modifying signal requires crossing an intensity threshold that moderate exercise does not reach.

SPARX required 80–85% maximum heart rate. Forced cycling required 30% above voluntary cadence — a threshold that patients could not reach under their own effort, which is why the motor assistance was necessary. The HIIT protocols that showed the strongest signal drove participants well above the moderate exercise range.

Stretching did nothing. Moderate treadmill exercise improved function but not progression. Tai Chi helped with balance but not neurodegeneration.

The honest interpretation: not all movement is equal. Only exercise that crosses a specific physiological threshold appears to interact with the disease process itself. The mechanism behind that interaction — dopamine preservation, mitochondrial signaling, a muscle-derived hormone called irisin — is where the biology gets genuinely remarkable.

I will dive into the actual biology behind these trials in the future.

What Comes Next

What Comes Next

If you have a family member with early Parkinson’s disease — or if you are at an age where these questions are beginning to feel personal — the practical takeaway from the clinical evidence above is this:

• High-intensity aerobic exercise at 80–85% maximum heart rate, four sessions per week, is the protocol with the strongest evidence base. It is not a guarantee. But it is the only non-pharmacological intervention in Parkinson’s research with a credible signal that it may reach the disease itself.

• Intensity is the variable. Moderate exercise improves quality of life. High-intensity exercise may influence disease progression. That distinction, rarely communicated clearly, matters enormously.

• The window matters. The pre-symptomatic phase — the 10–20 years before diagnosis — may be when exercise has the greatest potential impact. The prevention data is the subject of Article 3.

• This evidence applies specifically to idiopathic Parkinson’s disease. Related conditions, such as Multiple System Atrophy, have different underlying biology and may respond differently to exercise interventions.

• For those looking to act on this evidence, structured and medically supervised programs are increasingly available through organizations such as the Parkinson’s Foundation, certified therapy networks like LSVT Global, and community-based programs such as Rock Steady Boxing. Academic centers, including the Cleveland Clinic and Northwestern University, are also actively studying and implementing these protocols.

But before prevention, we need to understand the mechanism.

Why does pushing your body to 80% of its maximum heart rate interact with a disease defined by dying neurons? What is actually happening inside the brain — and inside the muscle — when a Parkinson’s patient exercises at high intensity?

That answer lives at the molecular level. And it is considerably more interesting than most people realize. I will talk about this later.

Fuel the science ☕✨

All Verified Links in One Place

🔗 SPARX Phase II (PubMed): https://pubmed.ncbi.nlm.nih.gov/29228079/

🔗 SPARX Phase II (JAMA Neurology): https://jamanetwork.com/journals/jamaneurology/fullarticle/2664948

🔗 SPARX3 ClinicalTrials.gov: https://classic.clinicaltrials.gov/ct2/show/NCT04284436

🔗 SPARX3 protocol paper: https://link.springer.com/article/10.1186/s13063-022-06703-0

🔗 CYCLE-II study design (PMC): https://pmc.ncbi.nlm.nih.gov/articles/PMC8632855/

🔗 CYCLE-II ClinicalTrials.gov: https://clinicaltrials.gov/study/NCT04000360

🔗 DAT imaging — De Laat 2024 (npj open access): https://www.nature.com/articles/s41531-024-00641-1

🔗 Ridgel cycling 2019 (PMC open access): https://pmc.ncbi.nlm.nih.gov/articles/PMC6421744/

🔗 PRET-PD resistance training (PMC): https://pmc.ncbi.nlm.nih.gov/articles/PMC3701730/

🔗 Tai Chi NEJM 2012: https://www.nejm.org/doi/full/10.1056/NEJMoa1107911

🔗 Tai Chi PMC (free): https://pmc.ncbi.nlm.nih.gov/articles/PMC3285459/

🔗 Tango RCT (PubMed): https://pubmed.ncbi.nlm.nih.gov/21959675/

🔗 HIIT vs MICT RCT 2024: https://journals.physiology.org/doi/full/10.1152/japplphysiol.00219.2024

🔗 HIIT meta-analysis PLOS One 2023: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0293357

🔗 Sprint feasibility study: https://pubmed.ncbi.nlm.nih.gov/31838213/

🔗 Irisin neuroprotection (npj open access): https://www.nature.com/articles/s41531-023-00453-9

🔗 Irisin (PMC free): https://pmc.ncbi.nlm.nih.gov/articles/PMC9889817/

🔗 DBS in MSA (PMC): https://pmc.ncbi.nlm.nih.gov/articles/PMC10077954/

🔗 Physiotherapy in MSA-P: https://pubmed.ncbi.nlm.nih.gov/31621609/

🔗 MSC stem cells in MSA RCT: https://pubmed.ncbi.nlm.nih.gov/22829267/

🔗 MSC stem cells 2025 systematic review: https://www.tandfonline.com/doi/full/10.2147/BTT.S593367

🔗 Dance meta-analysis PLOS One 2020: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0236820

🔗 HIIT systematic review (PubMed): https://pubmed.ncbi.nlm.nih.gov/36607555/

There is a drug that was discovered in the soil of Easter Island in 1972. For decades, doctors used it to stop organ rejection in transplant patients and to fight cancer. Then scientists started noticing something strange: the people taking it seemed to be ageing differently.

Their immune systems looked younger. They got fewer infections. Certain cancers appeared less frequently. And in every animal species researchers tested — from yeast to mice to monkeys — the drug extended healthy lifespan, sometimes dramatically.

The drug is called rapamycin. It is already FDA-approved. It is already used in oncology wards and transplant units around the world. And right now, it is at the centre of the most serious scientific effort ever undertaken to slow human ageing.

This is what the clinical trials actually show — including some findings that haven’t yet made it into mainstream headlines.

What Turns the Ageing Switch On

To understand this, you need to know about one protein: mTOR.

mTOR — short for mechanistic Target Of Rapamycin — is essentially a master switch inside your cells. Think of it like a cellular accelerator pedal.

When mTOR is high, it’s full throttle. Cells shift into growth mode — ramping up their internal production systems, building new components, increasing energy use, and pushing toward growth and division. This is exactly what you want when you’re young. Growth, repair after injury, building muscle, and developing tissues — all of this depends on mTOR being active.

But mTOR has another state. When mTOR is low, cells shift out of growth mode entirely. Instead of building and expanding, they focus on repair, cleanup, and long-term stability. They start clearing out damaged components, restoring balance, and prioritising cellular health over cellular growth. This lower mTOR state is actually better for ageing systems — it’s the body’s way of maintaining quality over quantity.

When you eat — particularly protein and carbohydrates — your insulin rises, amino acids flood the bloodstream, and mTOR reads these signals as a green light to grow. But food isn’t the only trigger. Chronic stress, inflammation, and certain growth factors can all keep mTOR elevated.

The problem is this: as we age, mTOR tends to stay chronically high. And chronically high mTOR means the accelerator is stuck down — cells never shift into repair-and-cleanup mode. The result is accelerated cellular damage, rising inflammation, and the accumulation of dysfunctional cells. That is what drives ageing.

The Animal Data Is Extraordinary

Before we get to human trials, it’s worth understanding why scientists got so excited about rapamycin in the first place.

It starts with a worm.

C. elegans — a tiny, transparent roundworm — became one of the most important organisms in ageing research for one simple reason: it ages fast enough to study in a lab, and its biology is surprisingly relevant to our own. When scientists genetically downregulated mTOR in C. elegans, something remarkable happened. The worms lived dramatically longer — in some experiments, up to five times their normal lifespan.

This work was pioneered by scientists, including Dr Cynthia Kenyon, whose discoveries at UCSF fundamentally changed how we think about the genetics of ageing, and researchers at the Buck Institute for Research on Ageing, one of the world’s leading institutions dedicated to understanding why we age and what we can do about it. I worked at the Buck Institute for Research on Ageing as a postdoctoral scholar and replicated this work. That was biology telling you something real.

The same effect was observed when translated from worms to yeast. From yeast to flies. From flies to mice. The US National Institute on Ageing’s Interventions Testing Program, one of the most rigorous multi-site drug-testing programmes in existence, found that rapamycin extended mouse lifespan by up to 25%, even when treatment was initiated in old age. That last detail matters enormously.

And it didn’t stop at mice. Marmoset monkeys. Non-human primates. The biology kept translating. The mechanism kept working. No other drug has replicated this result across as many species. The consistency is what makes this scientifically serious — not hype, not one lucky experiment, but the same biology expressing itself across the entire tree of life.

The open question has always been: Does it translate to humans?

The Human Evidence: Where It Actually Stands

Here is where scientists have to be careful — and honest. We do not yet have a randomised controlled trial showing that rapamycin extends lifespan in humans. That trial would take decades. What we have instead are trials using proxy measures: immune function, biomarkers, physical performance, and brain health. These are the signals that tell us whether the biology is working.

And some of those signals are striking.

But before we get into the data, it’s worth understanding something important about why the human evidence is still limited — and it has nothing to do with the science.

Rapamycin is a generic drug. It has been off-patent for years. The cost of producing it is low. And because of that, no pharmaceutical company has any financial incentive to fund the large, long-term clinical trials needed to prove its longevity benefits in humans. There is no blockbuster profit waiting at the end of that research. So the trials simply don’t get funded through normal channels.

Almost every serious human trial on rapamycin for ageing has been crowdfunded, investigator-led, or run on shoestring academic budgets. 1, 2

That’s not a reflection of the science being weak. It’s a reflection of how broken the incentive structure of drug development is. The most promising anti-ageing compound in the history of biology is sitting largely unstudied for prevention — not because it doesn’t work, but because nobody will make money from proving it does.

That context matters when you look at what we do have.

The Mannick 2014 Trial — The Strongest Human Signal

In 2014, a landmark study published in Science Translational Medicine tested low-dose everolimus — a close rapamycin analogue — in 218 adults aged 65 and over. Participants received the drug for six weeks, then were given a flu vaccine.

The result: their immune response was approximately 20% stronger than placebo. More importantly, a key marker of immune ageing — a protein called PD-1 that accumulates on T-cells and essentially acts as a brake on immune function — dropped significantly.

As we age, our T-cells progressively accumulate this PD-1 brake. Our immune system becomes sluggish. We’re more vulnerable to infections, less capable of fighting cancer, and slower to heal. This study showed that rapamycin could partially reverse that process, making old immune cells behave more like younger ones.

This remains the most robust human clinical signal we have for rapamycin’s anti-ageing potential.

The PEARL Trial 2025 — The Most Recent RCT

In 2025, the results of the PEARL trial were published — the longest randomised controlled trial ever run on rapamycin in healthy older humans. True to form, it wasn’t funded by a pharmaceutical company. It was crowdfunded by the longevity community, raising over $180,000 to make it happen. Scientists and curious individuals are putting their own money into research that the system refuses to prioritise.

114 healthy adults aged 50 to 85 were randomly assigned to 5mg rapamycin weekly, 10mg rapamycin weekly, or placebo for 48 weeks. The results were nuanced.

The primary endpoint — a reduction in visceral fat — did not reach statistical significance. That was the headline that disappointed some people.

But the secondary findings were noteworthy: women in the 10mg group showed a statistically significant gain in lean tissue mass — roughly 5% more than placebo by week 48. The same group reported significant reductions in pain. A separate group taking 5mg reported meaningful improvements in general health and emotional well-being, measured using validated surveys.

Rapamycin's ability to build muscle and reduce pain in older women wasn’t even the hypothesis going in. It showed up in the data anyway.

What a 48-Week Trial Cannot Tell Us — And What We Need Next

Here is the limitation that almost no one mentions when discussing the PEARL trial results.

A 48-week trial shows us what rapamycin does. It does not show us what rapamycin prevents.

We saw muscle gain. Pain reduction. Better wellbeing. Clean safety. Those are meaningful signals. But what we didn’t — and couldn’t — measure is whether rapamycin was quietly doing something far more important in the background. Was it slowing the accumulation of pre-cancerous cells? Was it reducing amyloid plaque build-up in the brain? Was it delaying the biological processes that eventually manifest as Alzheimer’s, Parkinson’s, or metabolic disease?

A 48-week trial cannot answer those questions. Prevention requires time. Years. Possibly decades.

This is my view on where the field needs to go — and I say this as someone who has worked with this biology at the bench level.

What we need is a 10 to 20 year rapamycin trial in healthy middle-aged adults, tracking not just how people feel, but hard biological outcomes: cancer incidence, cognitive decline measured against validated biomarkers, Alzheimer’s and Parkinson’s disease progression markers, cardiovascular events, and epigenetic ageing clocks measured at regular intervals throughout.

The biology says it should. The mTOR pathway sits upstream of cancer, neurodegeneration, and metabolic disease. Chronically suppressing it — safely, intermittently, at low doses — should reduce the risk of all of them. That’s not speculation. That’s the logical consequence of everything the preclinical data shows.

But that trial will cost tens of millions of dollars and take a decade or more to complete. It won’t be funded by pharma. It will need either public funding, philanthropic investment, or a longevity community willing to back something bigger than a 48-week crowdfunded study.

That’s the next frontier. And it’s the one that matters most.

The Patent Loophole — And Why It’s Actually Good News

Generic rapamycin sits in a legal grey zone. It works. The biology is proven. But because it’s off-patent and cheap, no company can recoup billions in R&D investment by selling it. So scientists have found a workaround: rapalogs — patented variants of rapamycin designed to target mTOR in slightly different ways, with enough novelty to earn new patents and justify new investments.

Companies like Calico (backed by Google’s parent company Alphabet) have developed compounds like RTB101. Academic institutions and biotech firms are testing modified everolimus variants. The strategy is transparent: tweak the molecule just enough to patent it, then run the clinical trials that generic rapamycin will never get funded for.

Here’s the paradox: this patent workaround might be exactly what accelerates rapamycin research in humans. RTB101 is currently in trials for Parkinson’s. Everolimus variants are in Alzheimer’s studies. These aren’t happening because pharma suddenly cares about ageing — they’re happening because there’s a legal path to profit.

But there’s a second revolution happening in parallel. A new ecosystem of longevity-focused organisations — Lifespan.io, independent researcher networks, crowdfunding collectives — is building its own funding mechanisms. They’re not waiting for pharma. They’re running the trials themselves. The PEARL trial is just the beginning. This is what happens when the traditional system fails: communities build their own.

The science is no longer held hostage by pharmaceutical incentives. It’s finding other routes.

Beyond Ageing: What About Alzheimer’s, Cancer, and Parkinson’s?

This is where the science gets genuinely surprising.

Alzheimer’s Disease — The Most Striking Finding

Here is a finding that has barely made it into mainstream coverage: in people who carry the APOE4 gene — the highest-risk genetic variant for Alzheimer’s disease — just four weeks of rapamycin treatment increased hippocampal and caudate brain volume and restored cerebral blood flow.

Those are not minor findings. The hippocampus is the memory centre of the brain and one of the first regions damaged by Alzheimer’s. Cerebral blood flow is a key marker of brain health that declines with age and accelerates in those at risk of dementia.

The picture becomes more complex when you look at those who already have Alzheimer’s disease. A separate pilot study found that in people already diagnosed, rapamycin appeared to increase certain inflammatory markers and tau protein — a sign of disease progression. The implication is important: rapamycin may be a powerful prevention tool for those at risk, but potentially not helpful — and possibly counterproductive — once the disease has taken hold.

Two major trials are currently recruiting to investigate this further — the ERAP trial and the REACH trial — with results expected in the next few years.

Cancer — Already Established, Still Evolving

Rapamycin analogues are already FDA-approved cancer treatments. This isn’t speculative — it’s established medicine. The more interesting question for healthy people is whether rapamycin could prevent cancer from developing in the first place.

The animal data are consistent: across dozens of mouse cancer models, rapamycin robustly delays or prevents tumour development. Data from transplant patients taking rapamycin is suggestive of cancer-preventive effects in humans, though this has not been tested in a formal prevention trial.

Parkinson’s Disease — Too Early to Say

Early phase trials have explored rapamycin-related compounds in Parkinson’s patients, but the published outcomes data are thin. The mechanistic case is reasonable — mTOR inhibition promotes autophagy, the cellular clean-up process that is impaired in Parkinson’s — but the clinical evidence simply isn’t there yet. This is a watch-and-wait area.

A Word on Personalisation — And Caution

No two people are the same. In science, even in the best-case scenario with the best drugs, there are always outliers. Some people respond remarkably well. Others don’t respond at all. A small percentage — usually around 3% — may experience side effects or complications that the broader population doesn’t see. It depends on genetics, underlying conditions, other medications, and factors we don’t yet fully understand.

I’ve spoken to thousands of people taking rapamycin. The overwhelming majority report positive changes — improved energy, better muscle maintenance, clearer thinking, and reduced pain. Some have told me it genuinely changed their lives. I’ve even heard from someone giving rapamycin to their arthritic dog, and the dog went from barely moving to energetic and pain-free. These stories are real.

But rare cases exist. Wound healing impairment has been reported in a small number of people. Certain underlying conditions — autoimmune disorders, severe metabolic issues, compromised immune function — can interact with rapamycin in ways that require careful monitoring. The biology is sound, but your biology is unique.

So here’s my honest recommendation: if this excites you, do the research properly. Read the papers. Understand the mechanism. Then have a real conversation with a physician who actually knows about mTOR biology and rapamycin — not just someone who dismisses it, but someone who understands it. And if you do decide to try it, start low, monitor closely in the beginning, and stay in conversation with your doctor about what you’re experiencing.

The science is promising. Your individual case deserves individual attention.

Why This Matters Beyond the Science

There is one aspect of the PEARL trial that deserves more attention than it usually gets.

No pharmaceutical company will fund a rapamycin longevity trial. The drug is generic. Off-patent. There is no profit motive for industry to run the years-long, expensive trials needed to generate definitive evidence.

The PEARL trial was funded by regular people who wanted answers. Scientists, longevity enthusiasts, and curious individuals who crowdfunded a clinical trial because the system wasn’t going to do it for them.

That’s new. And it matters. The longevity community is funding its own science — and the science is starting to deliver.

Where Does This Leave Us?

Rapamycin is not a proven anti-ageing drug in humans. Anyone who tells you otherwise is overclaiming.

But it is the most biologically plausible, most consistently effective in animals, and most carefully studied candidate we have. The human data is catching up to the animal data. The safety profile, at low doses, is reassuring. The immune findings are real. The brain health signals in Alzheimer ’s-risk populations are striking.

The next five years of trials will tell us much more. For now, the honest position is this: we are watching something potentially historic unfold in real time — and unlike most things hyped in the wellness space, this one has the science to back up the excitement.

We are watching something potentially historic unfold in real time — and unlike most things hyped in the wellness space, this one has the science to back it up.

Fuel My Work ☕

Sources & Further Reading

Mannick et al. (2014). mTOR inhibition improves immune function in the elderly. Science Translational Medicine.

Moel et al. (2025). PEARL Trial: Rapamycin safety and healthspan metrics after one year. Aging (Albany NY).

Ham et al. (2022). Distinct and additive effects of calorie restriction and rapamycin in aging skeletal muscle. Nature Communications.

Richardson et al. (2020). Is Rapamycin a Dietary Restriction Mimetic? Journals of Gerontology: Series A.

NIA Interventions Testing Program — Rapamycin lifespan data. nia.nih.gov/research/dab/interventions-testing-program-itp

ERAP Trial & REACH Trial — ClinicalTrials.gov (ongoing, recruiting).

Let me ask you something. When you hear the word Ozempic, what comes to mind?

For most people, it’s weight loss. The before-and-after photos. The celebrity rumours. The shortage headlines. The commercial with the smiling woman who dropped four dress sizes.

That framing isn’t wrong exactly — GLP-1 receptor agonists do produce significant, sustained weight loss. But it is profoundly incomplete. And the gap between what the public understands about GLP-1 and what the science is actually showing right now is one of the most striking disconnects I’ve seen in medicine in a long time.

I don’t typically advocate for drugs. That’s not what this space is about. But when the data starts pulling me in a particular direction this clearly, I think we have an obligation to talk about it.

So let’s talk about it.

The Biology Lesson → The Biology Lesson That Changes Everything

GLP-1 stands for glucagon-like peptide-1. It’s a hormone your gut releases when you eat, and it signals to your pancreas to produce insulin, tells your stomach to slow down, and — crucially — travels to your brain.

That last part is where things get interesting.

GLP-1 isn’t just a metabolic signal. It’s also a neurotransmitter. GLP-1 receptors are expressed throughout the brain, including in areas that have nothing to do with appetite or blood sugar.

They’re found in the nucleus accumbens — your brain’s pleasure centre.

In the ventral tegmental area — the engine of your dopamine system.

Along the mesocortical limbic pathways that govern reward, craving, and motivation.

It influences a network:

brain (satiety, reward, impulse control), metabolism (insulin sensitivity, energy balance), inflammation (systemic tone), and the cardiovascular system (vascular function).

When you understand that architecture, the findings below stop being surprising. They start feeling inevitable.

The Alcohol Finding That Started This Conversation

In 2025, JAMA Psychiatry published a randomised, placebo-controlled Phase II trial testing low-dose semaglutide in 48 adults with alcohol use disorder over nine weeks.

The results: semaglutide significantly reduced alcohol craving, reduced drinks per drinking day, and led to greater reductions in heavy drinking compared to placebo.

Now, 48 people over nine weeks is a small trial. The authors were careful to call it ‘initial prospective evidence.’ Not all endpoints reached significance. This is not a proclamation that Ozempic cures alcoholism.

But it’s real, peer-reviewed human data. And it doesn’t exist in isolation.

A 2024 study in Nature Communications analysed electronic health records from 83,825 patients with obesity. Semaglutide users had a 50 to 56 percent lower risk of developing or relapsing into alcohol use disorder over 12 months compared to those on other anti-obesity medications. The same signal was held in a separate cohort of nearly 600,000 patients with type 2 diabetes.

When compared directly against naltrexone and topiramate — the current front-line medications for alcohol use disorder — semaglutide users had a 75 percent lower risk of recurrence.

A 2025 systematic review and meta-analysis in eClinicalMedicine pooled data from 14 studies, including over 5.2 million patients, and found GLP-1 receptor agonists were associated with reduced alcohol intake, lower relapse rates, and fewer alcohol-related diagnoses.

It’s Not Just Alcohol — It’s the Entire Craving System

If semaglutide is reducing alcohol craving, it’s not doing that because of anything specific to alcohol. What’s happening is far more fundamental: GLP-1 is modulating the dopamine reward system — the same system that underlies every form of craving.

The data on binge eating disorder make this clear. Multiple clinical studies show semaglutide significantly reduces binge eating episodes — not just because it creates fullness, but because it appears to reduce the compulsive, reward-driven pull toward food that defines the condition.

There’s also early but consistent evidence around nicotine. Preclinical models show GLP-1 receptor agonists reduce nicotine-seeking behaviour. Some observational human data suggest reduced smoking rates in GLP-1 users. Randomised trials are underway.

The picture that’s emerging isn’t ‘weight loss drug has bonus benefits.’ It’s something more fundamental: a metabolic hormone that regulates the brain’s entire reward architecture. We prescribed it to millions of people, thinking it was just about appetite.

This Video I made addresses this angle.

The Brain Health Findings Are Equally Striking

A 2024 study published in Nature Medicine analysed data from 1,016,387 patients with type 2 diabetes across the Swedish national health register. The findings: patients treated with GLP-1 receptor agonists had an 18 percent lower risk of Alzheimer’s disease and a 40 percent lower risk of Parkinson’s disease compared to those not on GLP-1 therapy.

The proposed mechanisms include reduced neuroinflammation, improved insulin signalling in the brain, and potential effects on amyloid accumulation. This is observational data — association, not proven causation. But the signal is large, consistent, and biologically plausible.

Multiple review papers, including a 2025 update in Endocrinology by Elisabet Jerlhag — the leading researcher in this space — now synthesise the evidence across Parkinson’s, Alzheimer’s, addiction, and psychiatric conditions. The convergence is striking.

This Video I made addresses this angle.

What the FDA Has Already Approved — Beyond Weight Loss

This is where the conversation shifts from ‘promising science’ to regulatory reality. Most people don’t realise how far the approved indications have already moved.

Here’s what’s actually been approved:

• Cardiovascular risk reduction (2024): The SELECT trial — 17,604 patients with obesity but without diabetes — showed a 20% relative risk reduction in major adverse cardiovascular events with semaglutide. The FDA approved this indication in March 2024. This is landmark. It extended the cardiovascular benefit to people without diabetes for the first time.

• Chronic kidney disease (January 2025): The FLOW trial studied 3,533 adults with type 2 diabetes and CKD. Semaglutide significantly reduced the composite kidney failure outcome, and the FDA expanded prescribing indications accordingly.

• Obstructive sleep apnea (December 2024): Two randomised controlled trials demonstrated a 55% reduction in apnea-hypopnea index with tirzepatide. FDA approved for moderate to severe OSA in people with obesity.

• Fatty liver disease / MASH (2024): The FDA approved semaglutide for metabolic-associated steatohepatitis — a serious form of fatty liver disease causing inflammation and scarring. A condition with very few prior treatment options.

So when people ask whether GLP-1s have benefits beyond weight loss, the answer is no longer just ‘the science suggests maybe.’ The answer is: the FDA has approved four separate non-weight indications in the last 18 months.

The Cancer Signal — Early, But Worth Knowing About

I want to flag this carefully, because it’s the kind of finding that gets distorted quickly.

A 2024 retrospective study found GLP-1 receptor agonists were associated with significant risk reduction across multiple cancer types — including esophageal, colorectal, endometrial, gallbladder, kidney, liver, ovarian, and pancreatic cancer — compared to insulin in people with type 2 diabetes.

This is observational, early, and not yet replicated in randomised trials. It may partly reflect the anti-inflammatory and metabolic effects we’ve already discussed rather than any direct anti-cancer mechanism. But the signal is real and the research community is paying attention to it.

We are not saying GLP-1 drugs prevent cancer. We are saying the data is interesting enough that we need to keep looking.

One More Update We Need to Know

There was a period where GLP-1 drugs carried a warning about suicidal ideation. It generated real concern, particularly among parents of adolescents on these medications.

In January 2026, the FDA requested removal of that warning.

This matters for how you talk to patients and readers about these medications. The mental health picture appears to be positive, not negative.

So, Who Should Actually Consider GLP-1 Therapy?

This is the most important practical question, and I want to give you an honest answer rather than a hedge.

Clear evidence-based candidates:

• People with obesity (BMI criteria plus comorbidities)

• People with type 2 diabetes

• Those with established high cardiovascular risk

• People with obstructive sleep apnea and obesity

• Those with metabolic-associated fatty liver disease

Grey zone — physician-guided, case by case:

• Prediabetes with strong family history

• Metabolic syndrome

• Significant compulsive eating patterns or food noise

• Alcohol use disorder — very early evidence, not yet standard of care

Not currently supported by evidence:

• Metabolically healthy individuals seeking optimisation or longevity

• Routine preventative use in low-risk populations

That last category is where social media is running well ahead of the data. GLP-1 drugs are powerful tools for correcting metabolic and behavioural dysregulation. The key question is always: are you correcting dysfunction, or overriding a system that’s already working?

The Trade-Offs People Don’t Talk About Enough

GLP-1s shift biology, but they come with real considerations that get glossed over in the enthusiasm.

• GI side effects: Nausea, vomiting, constipation — common, usually dose-dependent, often manageable but not always.

• Muscle and lean mass: This is more nuanced than the headlines suggest. Much of the reported lean mass loss appears to come from the liver rather than skeletal muscle. But resistance training and adequate high-quality protein intake are not optional — they’re essential during therapy.

• Nutritional gaps: Eating significantly less means the risk of missing essential nutrients increases. Vitamins B12 and D, folate, magnesium, and iron all warrant attention. Smaller meals need to be nutrient-dense, not just smaller.

• Bone density: Rapid weight loss and reduced nutrient intake can affect bone density over time. Worth monitoring in longer-term use.

• Unknown long-term effects in low-risk populations: The long-term safety data comes primarily from people with diabetes and obesity. We have less data on healthy people using these drugs for optimisation purposes. That gap matters.

The question worth sitting with: are you correcting a dysfunction, or are you overriding a system that’s functioning well? The risk-benefit calculation is genuinely different depending on the answer.

What We’re Actually Looking At

For decades, medicine has treated addiction, obesity, neurodegeneration, and metabolic disease as largely separate problems with separate solutions. What the GLP-1 data is hinting at — carefully, with appropriate caveats — is that these conditions may share more biological territory than we thought.

That craving and metabolism and neurodegeneration and cardiovascular risk might all be sitting on the same underlying system. And that a molecule we stumbled into for blood sugar control might be touching all of it at once.

That is a genuinely extraordinary possibility. It doesn’t mean the drug is a cure for everything. It means our map of human biology might be missing something important — and GLP-1 might be the thing that forces us to redraw it.

I want to hear from you. Has any of this surprised you? For those of you on GLP-1 medications for any reason — have you noticed anything beyond what you were prescribed it for? And what questions do you have that I haven’t addressed here?

Drop a comment, reply to this email, or join the chat. This is the conversation I’m most interested in having.

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Key Sources

Hendershot et al. Once-Weekly Semaglutide in Adults With Alcohol Use Disorder. JAMA Psychiatry. 2025;82(4):395–405.

Wang et al. Associations of semaglutide with incidence and recurrence of alcohol use disorder. Nature Communications. 2024;15(1):4548.

GLP-1 RAs and alcohol consumption: systematic review & meta-analysis. eClinicalMedicine (The Lancet). November 2025. 14 studies, n = 5,262,218.

GLP-1 receptor agonists and risk of neurodegenerative disease: nationwide register study. Nature Medicine. 2024. n = 1,016,387.

Jerlhag E. GLP-1 receptor agonists: Promising therapeutic targets in alcohol use disorder. Endocrinology. 2025;166(4):bqaf028.

SELECT trial: Semaglutide and cardiovascular outcomes in obesity without diabetes. NEJM. 2024. n = 17,604.

FLOW trial: Semaglutide and chronic kidney disease outcomes. NEJM. 2024. n = 3,533.

Tirzepatide and obstructive sleep apnea: SURMOUNT-OSA trials. NEJM. 2024.

Cancer risk associations with GLP-1 receptor agonists vs insulin. Retrospective cohort study. 2024.

FDA removal of suicidal ideation warning for GLP-1 medications. January 2026.

Hendershot et al., JAMA Psychiatry, 2025;82(4):395–405. DOI: 10.1001/jamapsychiatry.2024.4789

The Result That Changed the Room

In September 2025, a late-breaking abstract at ECTRIMS — the world’s largest multiple sclerosis conference, held in Barcelona — stopped the room. A Cambridge University team had produced a statistically significant signal of actual myelin repair in living human MS patients. Not in mice. Not in a dish. In people.

The drugs involved were not experimental biologics requiring years of novel synthesis and hundreds of millions in development costs. One was a hay fever antihistamine you can buy over the counter for a few bucks. The other was a diabetes drug prescribed to hundreds of millions of people worldwide, available in generic form for pennies per pill. Together, they produced something the field had spent fifty years failing to demonstrate.

The lead researcher put it plainly: ‘I am increasingly sure remyelination is part of the solution. We are on the brink of a new class of treatments.’

What MS Actually Does to Your Nerves (and Why It’s Not Always Forever)

Multiple Sclerosis (MS) is an autoimmune disease in which the immune system attacks myelin, the fatty sheath that coats and protects nerve fibres in the brain and spinal cord.

Myelin is not decorative. It is what allows nerve signals to travel at speed. Healthy myelinated fibres conduct signals at up to 70 metres per second — roughly the speed of a fast car. Strip the myelin away, and that drops to less than two metres per second. Signals slow, misfire, or fail entirely. That is where the symptoms come from — the fatigue, weakness, vision problems, pain, and cognitive fog that define the disease.

Here is the crucial thing most people do not know: in early, active MS, the nerve fibre beneath the damaged myelin is often still alive. The wire exists. It just has no insulation.

The brain has dedicated repair cells — oligodendrocyte precursor cells, or OPCs — that exist specifically to remyelinate damaged fibres. In MS, those cells lie dormant. They are present throughout the brain and spinal cord, waiting to be activated. But something is stopping them.

If the nerve fibre remains unrepaired long enough, it eventually dies. That is permanent disability. The window for repair is before that happens, and until this trial, nobody had convincingly shown that the window could be reopened using drugs.

Two Locks, Two Keys

The mechanism behind the CCMR-Two combination is elegant once you understand it.

OPCs (oligodendrocyte precursor cells) in the MS brain are blocked from maturing into mature myelin-producing cells by two separate problems. Clemastine and Metformin together address them both.

The first lock involves muscarinic receptors.

OPCs carry receptors on their surface called M1 and M3 muscarinic receptors. When these receptors are activated, they prevent the cells from maturing. Clemastine, a first-generation antihistamine, also acts as a muscarinic antagonist. In other words, it blocks those receptors and releases the brake that was stopping OPCs from becoming myelin-producing cells.

This is not why clemastine was originally developed. It was identified in a 2014 drug screen at UCSF led by Mei and colleagues, where researchers tested hundreds of existing medications on OPCs to see whether any unexpectedly promoted myelin repair. Clemastine stood out. Not because it is an antihistamine, but because of what it does to those receptors.

It’s important to understand that clemastine is not working here because it’s an antihistamine. Its effect comes from its action on muscarinic receptors. That means this is not something you can expect from antihistamines in general.

Most antihistamines don’t share that mechanism — so you can’t swap one for another.

The second lock is metabolic exhaustion.

Even when that receptor brake is removed, OPCs in the aging or MS-affected brain often lack the cellular energy needed to finish maturing. Metformin activates AMPK, a key cellular energy sensor that helps restore metabolic function. In effect, it gives the cells the energy they need to complete the repair process once the muscarinic block is lifted.

Metformin wakes the cells up. Clemastine releases the brake.
Together, they allow the repair process to move forward.

It’s very important to understand that Clemastine is not doing its usual function as an antihistamine. It now has a new role in repair. So other antihistamines will not work here.

What the Trial Showed

The CCMR-Two trial was a Phase 2a randomized, double-blind, placebo-controlled study conducted at Cambridge. Around 70 people with relapsing-remitting MS were enrolled and followed for 24 weeks.

The primary outcome was visual evoked potential (VEP) latency — a measure of how quickly electrical signals travel along the optic nerve. It is one of the most sensitive non-invasive ways researchers can detect changes in myelin in living patients.

The numbers

VEP latency improved approximately 1.3ms versus placebo (control or non-drug treated).

Adjusted difference: -1.2ms (95% CI -2.4 to -0.1; P=0.042) — statistically significant.

No disability improvement was detected at six months — but that may say more about the trial duration than the biology. Repair can happen first, while functional recovery takes longer to appear. Future trials are expected to follow patients for longer to capture these effects. Longer, larger trials are already being planned — and those results will matter. Importantly, disability did not worsen during this time. This shows overall signs of improvement.

The scientists had previously conducted a trial, called the ReBUILD trial, published in The Lancet in 2017, which showed that clemastine alone produced a VEP latency improvement of 1.7 to 3.2ms — the first randomized controlled trial to show remyelination in living MS patients.

CCMR-Two adds metformin to address the metabolic component and tests whether the combination outperforms the single drug. It does. This was amazing!

Why These Drugs Being Already Approved Changes Everything

This is the part of the story that does not get enough attention — and for MS patients and the wider research community, it may be the most important angle of all.

Both clemastine and metformin are already FDA-approved and have been for decades. Clemastine has been approved since 1977. Metformin has been approved in the United States since 1994 and has been in continuous clinical use in Europe since the 1950s. Between them, they have been taken by hundreds of millions of people over generations.

What Existing FDA Approval Means in Practice

Decades of human safety data already exist. Toxicology studies are complete. Drug interaction profiles are well characterized. Side effect profiles are known — including who should not take them (narrow-angle glaucoma patients should not take clemastine; standard metformin GI side effects are well documented and manageable with extended-release formulations).

The regulatory pathway for a new indication using alre

ady approved drugs is significantly shorter and less expensive than that for approving a novel compound. Regulators already know these molecules are safe in humans.

For a Phase 3 MS trial, this matters enormously. Researchers designing the trial do not need to establish basic human toxicity from scratch — they are working with a known safety profile and refining dosing and monitoring for a specific population and indication. The path from Phase 2 signal to potential approval is materially shorter than it would be for a novel drug.

Then there is the economics. Metformin costs less than $10 for a month’s supply in generic form. Clemastine is similarly cheap and widely available over the counter in many countries. Neither drug is under patent. Neither can be exclusively monetized by a pharmaceutical company. There is no blockbuster profit waiting at the end of this pipeline, which is precisely why this research has been left to an academic institution rather than a major pharmaceutical company.

Pharma cannot own this. A university found it. That is not a coincidence — it is what happens when the profit motive is removed from the equation.

Cambridge University is a non-profit academic institution. The CCMR research group is funded by research charities, public bodies, and the MS Society — not by companies with a financial interest in the outcome. The research question was asked because it was scientifically important, not because it was commercially lucrative. The result is publicly owned science, conducted in the public interest, using drugs that already belong to everyone.

This also means the MS community does not need to wait for a pharmaceutical company to decide this is worth developing. Academic trial programmes, charity funding, and health service adoption pathways exist specifically for repurposed drugs with proven safety profiles. The Cambridge group is already running the Octopus trial — testing metformin alone in progressive MS — funded by the same non-commercial infrastructure.

What This Is Not — The Honest Caveats

MS research has a difficult history of Phase 2 results that did not translate into Phase 3 success. This result deserves to be taken seriously — and taking it seriously means being precise about what it shows and does not show.

This is Phase 2a with approximately 70 patients. The effect size is modest — 1.2ms VEP improvement. No functional disability improvement was detected at six months, and the trial was in relapsing-remitting MS only. Whether the results translate to progressive MS, where OPC populations may be more depleted, is a separate question requiring separate trials. The full peer-reviewed publication has not yet been released — the data presented at ECTRIMS 2025 was a conference abstract.

The researchers have explicitly and repeatedly said people should not self-medicate with this combination outside a clinical trial. The clemastine dose used — 5.36mg twice daily — is significantly higher than standard over-the-counter antihistamine dosing of approximately 1mg twice daily. The long-term safety of this specific combination alongside different MS disease-modifying therapies has not been fully characterized. Anyone with narrow-angle glaucoma should be aware that clemastine is contraindicated in that condition.

Why the Proof of Concept Is the Prize

Even with those caveats, the significance of this result goes beyond its numbers. The question it answers is not whether clemastine and metformin are the final MS treatment. The question is whether remyelination is biologically achievable in living human patients through pharmacological intervention. The answer — for only the third time in the history of MS research — is yes!!

The repair pathway exists. It can be switched on. Two drugs that already exist, already have safety profiles, already have regulatory precedent, and cost almost nothing can move the needle. The specific drugs may be refined — PIPE-307 is already in Phase 2, designed to achieve the same muscarinic antagonism with better targeting and less anticholinergic burden. But the biological pathway is validated, the mechanism is understood, and the field has shifted.

For 2.9 million people who were told the damage was permanent, the question has changed. Not if. How much. How fast. And when.

Nothing in this article constitutes medical advice. All claims are drawn from peer-reviewed literature and conference data as of early 2026. Full peer-reviewed publication of CCMR-Two trial data is pending.

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Sources

• CCMR-Two trial — ECTRIMS 2025 late-breaking abstract. ClinicalTrials.gov: NCT05131828

• ECTRIMS podcast Episode 60: ectrims.eu/podcast/episode-60-positive-remyelination-trial-results-late-breaking-at-ectrims-2025/

• Cambridge press release: cam.ac.uk/research/news/common-diabetes-drug-and-antihistamine-could-together-repair-multiple-sclerosis-damage-trial-finds

• MS Society coverage: mssociety.org.uk/research/news/trial-results-suggest-drug-combo-could-boost-myelin-repair-relapsing-ms

• ReBUILD trial (clemastine alone): Green et al., The Lancet 2017

• Clemastine OPC drug screen: Mei et al., Science Translational Medicine, UCSF 2014

• Trial protocol (peer-reviewed): Springer Nature Trials journal — CCMR-Two protocol

• Simvastatin MS-STAT2: The Lancet 2022

Two people can both be 50 years old.

But one might have a heart that functions as if it belongs to a 65-year-old, while their brain still runs like that of someone in their early 40s. The other person might have the opposite problem entirely.

We’ve always thought of aging as something that happens to the whole body at roughly the same pace. You get older, and everything gets older with you.

New science says that’s wrong — and the implications for how we detect and prevent disease could be significant.

But more importantly, in many cases, the organ that ages fastest is the one most likely to develop disease later.

Waves of Change: How Aging Accelerates at Key Ages You Wouldn’t Expect

Before we get into organs, there’s a 2019 finding that didn’t get nearly enough attention.

Researchers at Stanford analyzed blood samples from hundreds of people across different ages and found that aging doesn’t just creep along steadily. It appears to happen in distinct waves, with three major biological turning points hitting at around ages 34, 60, and 78.

At each of these ages, a large number of proteins in the blood show sudden, noticeable changes. The body doesn’t just quietly age. It shifts.

This was surprising because 34 feels young. Most people at that age don’t think of themselves as “aging.” But biologically, something changes — the first of several inflection points in how the body operates.

That study planted an important seed: Aging is more complex and more uneven than we assumed.

What came next pushed that idea much further.

Your Body’s Secret Clocks: Why Organs Age on Their Own Timelines

In 2023, the same Stanford researchers published a landmark study in Nature that took this idea to a new level.

They analyzed blood samples from roughly 1,400 people, measuring nearly 5,000 different proteins circulating in the bloodstream. Then they validated what they found by testing the approach on another 4,000 people.

Here’s the key insight: many of these proteins don’t come from just anywhere in the body. Specific organs release specific proteins into the blood as part of their normal daily activity. The heart releases certain proteins. The kidneys release others. The brain releases its own distinct set.

By tracking which proteins came from which organs, the researchers were able to estimate something remarkable: the biological age of 11 different organs and systems in the body, including the brain, heart, liver, kidneys, lungs, pancreas, muscles, immune system, arteries, fat tissue, and intestines.

And what they found was striking.

About one in five adults had at least one organ aging significantly faster than you’d expect for their age. A 50-year-old might have kidneys functioning like a 60-year-old’s, while their heart appeared younger than average.

In other words, your body doesn’t run on one clock. It runs on many — and they don’t all keep the same time.

Speeding Clocks = Higher Risks: Why Accelerated Aging Spells Trouble

Interesting as it is to know your organs age at different speeds, the most important finding was what that difference meant.

When researchers followed participants over time, accelerated organ aging turned out to predict disease risk — often years before any symptoms appeared.

A biologically older heart was linked to higher rates of heart failure and cardiovascular disease. A faster-aging kidney predicted metabolic disease and high blood pressure. A biologically older brain was associated with cognitive decline and a higher likelihood of dementia.

Even relatively small differences mattered. People who had even one organ aging significantly faster than their peers faced a 15% to 50% higher risk of dying over the following 15 years, depending on which organ was affected. People with two or more rapidly aging organs faced risks up to six times higher than those with none.

This is the shift that aging researchers have been working toward for decades: moving from detecting disease after damage is already done to identifying which organs are under stress before anything goes wrong.

The Power Duo: Brain and Immune Systems as Aging’s Master Keys

A large follow-up study published in Nature Medicine in 2025 pushed the question further. This wasn’t a small replication effort — it analyzed data from nearly 45,000 people in the UK Biobank, one of the largest biological research databases in the world.

The researchers asked: across all 11 organ systems, which ones most strongly predict how long and how well you’ll live?

Two stood out above all the others.

People whose blood proteins suggested accelerated aging in those two systems were significantly more likely to experience chronic disease, physical decline, and earlier death — regardless of what their other organs were doing.

This fits with what biology has been telling us in other ways.

The brain regulates almost everything: metabolism, stress hormones, sleep, and behavior. When it starts to decline, effects ripple outward to the whole body. The immune system, meanwhile, is the body’s master maintenance crew. It clears out damaged cells, manages inflammation, and repairs tissues. When it ages, inflammation rises — and sustained inflammation underlies nearly every major chronic disease, from heart disease to Alzheimer’s to cancer.

These two systems may sit closer to the center of aging than we previously understood. When they go, a lot else tends to follow.

Beyond the Barrier: Why Brain Signals Appear in Blood Tests

This might be the part that’s hardest to believe. The brain is protected by something called the blood-brain barrier, a tightly controlled filter that limits what can pass between the brain and the rest of the body. So how can a blood sample tell us anything about brain aging?

It turns out the brain is not as isolated as we once thought.

Brain cells and the blood vessels running through them constantly release proteins during normal activity, and even more so under stress. Small fragments of those molecules do make it into circulation, and they carry information about what’s happening up there.

When researchers looked at which proteins most strongly signaled accelerated brain aging, they found them clustered around processes central to brain disease: inflammation, disrupted blood flow, changes in how neurons communicate, and breakdown of the structural scaffolding that holds brain tissue together.

These are the same processes that drive Alzheimer’s disease.

Here is where the numbers get striking. Having an especially aged brain was associated with a 3.1 times higher risk of developing Alzheimer’s disease, roughly the same as carrying one copy of APOE4, which is the strongest known genetic risk factor for the condition. On the flip side, having a biologically youthful brain was linked to a 74% lower risk, a level of protection comparable to carrying two copies of the protective APOE2 gene variant.

Put together, people with aged brains had a 13.5 times greater risk of developing Alzheimer’s compared to those with youthful brains.

To put that in context: APOE4 is the gene variant that people get tested for when they want to understand their Alzheimer’s risk. It is the gold standard of genetic risk factors for the disease. The fact that brain aging detected through a blood test carries comparable predictive power is a significant finding.

And crucially, these associations held up independently of age, sex, and a person’s APOE genotype, Stanford Medicine, meaning this is not simply measuring the same thing as genetic testing. It is capturing something additional and separate.

Alzheimer’s currently has no cure, and by the time someone receives a diagnosis, significant brain damage has typically already occurred, often after years of silent deterioration. The disease does not announce itself. What this research suggests is that the molecular warning signs could be visible in a routine blood draw years or even decades before a single symptom appears. That would represent one of the most consequential shifts in dementia medicine in a very long time.

Game-Changer Ahead: How Organ Age Tests Could Revolutionize Medicine

If these findings continue to hold up in larger clinical studies, they could reshape how medicine approaches aging and prevention.

Right now, doctors mostly wait for the disease to arrive and then treat it. A patient develops heart failure and gets medication. A patient shows signs of cognitive decline and gets tested for dementia.

What these studies describe is a different model entirely: measuring the biological age of specific organs from a routine blood draw, identifying which systems are aging fastest, and intervening before anything breaks.

Someone whose blood proteins suggest accelerated cardiovascular aging might start intensive heart-health interventions in their 40s rather than waiting for a diagnosis in their 60s. Someone with signs of immune aging might focus on anti-inflammatory strategies, sleep, and other factors known to slow that process.

The goal wouldn’t just be a longer life — it would be healthier years, with more function and less disease.

Caveats and Cautions: The Holes in Our Understanding of Aging

The researchers behind these studies are careful to point something out, and it’s worth taking seriously.

These are statistical models, not direct measurements of organ health. They identify correlations between protein levels and biological outcomes across large populations. They’re genuinely predictive, but they haven’t yet been validated as clinical tools — meaning your doctor can’t order an “organ age” blood test today.

The science is moving fast, though. Larger trials are underway, and some researchers believe tests like these could be in clinical use within a few years.

Paradigm Shift: Aging as Multiple Journeys, Not One Path

For most of human history, aging was something that happened to you, uniformly and inevitably.

What this research suggests is that aging is more like a collection of separate processes, running in different organs, at different speeds, some of which can be detected, tracked, and potentially slowed.

This is not a fringe idea from one research group. Looking beyond the Stanford papers, there are now more than 20 independent peer-reviewed studies from separate research teams around the world pointing in the same direction. Different methods, different populations, different labs, all arriving at a remarkably consistent conclusion: organs age at different rates, those differences are measurable, and they predict disease. When that many independent lines of evidence converge, it stops being a hypothesis and starts becoming a framework.

And the scientific community is already thinking about what comes next. If we can measure which organs are aging fastest, the logical next step is finding ways to slow them down, to keep each organ biologically younger for longer, and to prioritize intervention where it is most needed. Not a single pill. Not one universal treatment. Something far more personal than that.

This is a different way of thinking about health entirely. The goal is not simply to live longer. It is to protect the years that actually feel like living, to extend genuine health and function rather than just pushing the endpoint further out.

The question medicine has always asked is: how old are you?

The question it may soon be asking instead is: which part of you is aging fastest, and what are we going to do about it right now?

That shift, if it happens, would be one of the most significant changes in how we think about human health in a very long time—not reacting to the disease after it arrives. Anticipating it, organ by organ, years in advance, and choosing a different path before the damage is done.

And here is the part that should actually give you hope. You are not passive in this. The lifestyle choices you make every day, how you sleep, what you eat, how you move, and how you manage stress are already talking to your organs. Science is getting better at telling us which ones need the most attention. What we do with that information can make a bigger difference than most of us realize.

Read about Alzheimer’s Biomarkers.

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Sources:

1. Oh HS, Rutledge J, Wu J, et al. Organ aging signatures in the plasma proteome track health and disease. Nature. 2023;624:164–172. doi:10.1038/s41586-023-06802

2. Lehallier B, Gate D, Schaum N, et al. Undulating changes in human plasma proteome profiles across the lifespan. Nat Med. 2019;25(12):1843–1850. doi:10.1038/s41591-019-0673-2.

3. Oh HS, Lehallier B, Wyss-Coray T, et al. Plasma proteomics links brain and immune system aging with healthspan and longevity. Nat Med. 2025. doi:10.1038/s41591-025-03798-1.

For decades, we’ve hunted for what goes wrong in Alzheimer’s. But what if the real story starts with what goes missing?

For years, Alzheimer’s headlines have sounded familiar: new toxic protein, new drug target, new failed trial. The story has largely centered on what goes wrong inside the brain.

But a recent paper published in Nature by researchers at Harvard Medical School asks a different and surprisingly simple question:

What if part of Alzheimer’s starts when the brain loses something it normally relies on?

That unexpected candidate is lithium.

Not the psychiatric medication people may recognize, and not high drug doses. The researchers are talking about tiny, naturally occurring trace amounts already present in healthy brains.

The discovery is generating real scientific interest, not because it represents a treatment yet, but because it changes how researchers may think about the disease itself.

The Unexpected Culprit Hiding in Plain Sight

The Harvard team analyzed human brain tissue from individuals across the Alzheimer’s spectrum: cognitively healthy adults, people with mild cognitive impairment, and patients diagnosed with Alzheimer’s disease.

They measured concentrations of 27 different metals and trace elements.

Only one showed a consistent and early decline.

Lithium.

Levels were already lower in people with mild cognitive impairment, often years before dementia develops. That timing matters. It suggests lithium loss may occur early in the disease process rather than simply reflecting damage that has already happened.

Scientists were intrigued. Then they uncovered something even more surprising.

Why Lithium Matters in the First Place

At clinical doses used in psychiatry, lithium stabilizes mood by adjusting signaling networks across the brain. At tiny physiological levels, researchers suspect it may help cells maintain stability during aging and stress.

So what exactly is lithium influencing?

Microglial function

Microglia are the brain’s cleanup crew. They patrol tissue, clear debris, and help remove toxic protein buildup. When microglial function weakens, waste products like amyloid are cleared less efficiently. Over time, that reduced clearance can contribute to the accumulation of toxic material associated with Alzheimer’s disease.

Regulation of inflammation

Inflammation in the brain is a double-edged sword. Short-term inflammation helps repair damage. Chronic, unresolved inflammation can injure neurons. Lithium has been shown to modulate inflammatory signaling pathways. When lithium levels fall, inflammatory responses may become more dysregulated, creating an environment that favors neurodegeneration.

Neuronal stress resistance

Brain cells are constantly managing oxidative stress, metabolic strain, and protein misfolding. Lithium influences pathways involved in cellular stress responses. Lower lithium availability may reduce a neuron’s ability to cope with long-term stress, potentially making cells more vulnerable to damage.

Synaptic stability

Memory depends on stable synaptic connections between neurons. Lithium interacts with signaling systems that support synaptic maintenance and plasticity. Disruption of these pathways may contribute to the gradual weakening of neural networks seen in Alzheimer’s disease.

GSK-3β activity

Lithium inhibits an enzyme called GSK-3β, which is closely linked to tau phosphorylation. Overactive GSK-3β signaling has been implicated in tau pathology, one of the defining features of Alzheimer’s disease. Reduced lithium levels could theoretically allow this pathway to become more active.

In this view, lithium is not acting like a traditional drug targeting one single receptor. It behaves more like a subtle regulator that helps the brain maintain balance across multiple systems.

The Vicious Cycle No One Saw Coming

Amyloid plaques, the sticky protein clumps long associated with Alzheimer’s disease, appear capable of binding lithium ions.

In plain language, plaques may physically trap lithium, preventing nearby brain cells from using it.

This creates a potential feedback loop:

1. Amyloid plaques begin to accumulate.

2. Lithium becomes trapped and less available.

3. Microglia, the brain’s cleanup cells, become less effective.

4. Amyloid clearance slows down.

5. More plaques form, trapping even more lithium.

Instead of acting only as toxic debris, amyloid may also disrupt a protective system that normally helps the brain maintain balance.

The disease may involve both damage and depletion.

Yes, It Reversed Memory Loss - in Mice

To test whether lithium loss might actively contribute to disease, researchers turned to Alzheimer’s mouse models.

When lithium levels were reduced, pathology worsened:

• more amyloid accumulation

• increased tau changes

• greater inflammation

• synaptic and myelin loss

• measurable memory decline

When lithium was restored using extremely low doses, including lithium orotate, several changes followed:

• Amyloid burden decreased

• Inflammatory markers improved

• cognitive performance recovered

• even older mice showed improvement

These results understandably caught attention.

But they also come with an important reminder.

The Reality Check

This research is preclinical.

No human trials have yet shown that lithium supplementation prevents or treats Alzheimer’s disease. Mouse studies frequently show dramatic improvements that do not translate into human patients.

Lithium is also not a harmless supplement. Even relatively low doses can affect kidney and thyroid function and require medical monitoring when prescribed.

The researchers themselves cautioned against self-experimentation based on these findings.

Scientific excitement does not equal medical advice.

Why Researchers Still Care About This Study

What makes this paper stand out is not a potential therapy. It is the question it introduces.

For decades, Alzheimer’s research has focused on identifying the toxic trigger.

This study instead asks whether the earliest change might be the failure of a protective system.

Increasingly, neurodegenerative diseases look less like single protein disorders and more like breakdowns in the brain’s long-term maintenance systems. Aging may slowly weaken the mechanisms that normally keep damage under control.

A Shift in Perspective

If this idea holds up, Alzheimer’s may not begin solely when harmful proteins appear. It may begin when the brain quietly loses resilience.

That shift changes how scientists think about prevention, early detection, and treatment strategies.

Even if lithium itself never becomes a therapy, understanding why its levels fall could reveal new pathways that help protect the brain earlier in life.

The Takeaway

It is a new scientific angle on a disease that has resisted simple explanations for decades.

This also changed the way we approach science. This taught us not to focus on “what’s attacking the brain?” but to focus on mechanisms that stop the brain from protecting itself. This leads to long-term preservation and lifestyle changes that can help us eliminate this disease.

Sometimes progress in science comes from discovering a new molecule. Other times it comes from asking a better question.

This study does the latter.

And for Alzheimer’s research, that may be just as important.

Source:
Yankner Lab, Harvard Medical School. Lithium deficiency and the onset of Alzheimer’s disease. Nature, 2025.

Learn about Alzheimer’s Biomarkers that can detect Alzheimer’s 20 years before symptoms show up. FDA approved!!

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A small group of cancer patients skipped breakfast before their immunotherapy treatments. When researchers examined their immune cells afterward, something stood out.

The T cells responsible for killing cancer were multiplying more aggressively and showing stronger signs of activation. The patients had not taken a new drug or changed their treatment protocol. They had simply changed when they ate.

Two rigorous scientific studies now suggest that short periods of fasting may alter how the immune system behaves during cancer treatment. Here’s why that matters.

Cancer cells and our immune cells both rely on energy to survive and function, and inside tumors, they are competing for the same resources. For years, scientists assumed that reducing nutrient availability would simply weaken cells across the board.

But these new studies suggest something more surprising. A brief, carefully timed fasting period appears to trigger metabolic changes that cancer cells struggle to adapt to, while immune cells may continue functioning effectively, or even become more active. This temporary shift could help immune cells do their job more efficiently during treatment.

Importantly, some of these findings were observed not only in animal studies but also in early human trials.

Why This Matters

Immunotherapy has changed cancer treatment over the past decade. Drugs that help the immune system recognize and attack cancer have saved lives. But they do not work for everyone. Some tumors resist treatment. Some patients experience severe side effects. Researchers are trying to understand why.

One growing area of interest is the tumor microenvironment. This is the local ecosystem around a tumor, including immune cells, blood vessels, nutrients, and chemical signals. Tumors compete with immune cells for fuel. If cancer cells dominate that competition, immune cells can become exhausted and ineffective.

That is where metabolism enters the picture. Food changes metabolism. Fasting changes it even more dramatically. The question researchers asked was simple. “Could short periods of fasting shift the metabolic environment in a way that helps immune cells do their job?”

Study One: A 16 Hour Fast and Immunotherapy

In early 2026, a paper titled “16-h fasting optimizes cancer immunotherapy in mice and humans” was published in the journal Cell Metabolism.

The researchers tested a practical intervention. A 16-hour overnight fast. This is not extreme starvation. For many people, it looks like finishing dinner at 6 pm and eating again at 10 am the next day.

What They Did in Mice

In mouse models of cancer, the researchers combined a 16-hour fasting window with immune checkpoint therapy, a common form of immunotherapy. They compared fasted mice to mice that ate freely.

They looked closely at what was happening inside the tumor.

They found that fasting changed nutrient availability within the tumor microenvironment. One specific change stood out. Levels of an amino acid called “isoleucine” increased within tumors during fasting.

Why does that matter?

Our immune system includes specialized “killer” cells called “CD8+ T cells” that can directly attack cancer cells. These T cells need fuel to function. In the fasting condition, the higher levels of isoleucine inside the tumor appeared to support stronger T cell activity … meaning … The T cells with isoleucine were better equipped to attack tumor cells. Fasting also changed how these T cells used energy and which genes they activated, changes that are typically seen when immune cells become more active.

Most importantly, when fasting was combined with immunotherapy, tumor control improved in mice compared to immunotherapy alone.

That is a strong preclinical signal.

What They Saw in Humans

This is where the study becomes especially interesting.

The researchers also looked at a small group of colorectal cancer patients receiving neoadjuvant immunotherapy, meaning immunotherapy given before surgery. Some patients underwent short-term fasting during treatment.

The study did not test whether fasting improved survival or tumor shrinkage in these patients. It was not a large randomized trial.

What they did measure was the immune response.

They also observed increased expression of genes linked to cytotoxic function. In other words, the immune cells showed signs of being more activated and ready to kill.

This is not proof that fasting makes immunotherapy cure more cancer in humans. But it is human data showing measurable immune changes during treatment. That is rare in the fasting literature and worth paying attention to.

Study Two: A Fasting Mimicking Diet and Immunotherapy

A related line of research was published in 2023 in another prestigious scientific journal called Nature Communications.

Instead of a daily 16-hour fast, this study used what is called a fasting mimicking diet. This is a short cycle of very low-calorie, low-protein, plant-based nutrition designed to trigger some of the biological effects of fasting while still providing limited nutrients.

This study focused on mouse models of melanoma treated with immune checkpoint inhibitors.

What They Found

When the fasting mimicking diet was combined with immunotherapy, tumor growth was delayed more than with immunotherapy alone. That aligns with the general theme seen in the 2026 paper. Dietary restriction appeared to enhance anti-tumor immune responses in mice.

But this study added another important dimension.

So here we have two separate research groups using two different dietary interventions. Both saw enhanced immune activity against tumors in mice when dietary restriction was paired with immunotherapy. One study also showed reduced treatment-related toxicity in animal models.

Together, these findings strengthen the idea that metabolic state influences how immunotherapy works.

How Could This Be Happening?

To understand this, we need to zoom out.

Cancer cells are metabolically aggressive. They consume large amounts of glucose and amino acids. Immune cells also need energy to function. Inside a tumor, there is competition.

Fasting shifts the body’s fuel sources. Blood glucose drops. The body increases fat breakdown and ketone production. Hormonal signals change. Nutrient availability shifts.

In the mouse study, fasting increased intratumoral isoleucine levels. That appears to have supported CD8-positive T cell function. The T cells showed metabolic and gene expression changes consistent with stronger cytotoxic capacity.

In broader research, fasting and fasting-like diets have been linked to changes in inflammation, insulin signaling, and cellular stress responses. All of these pathways can influence immune function.

The key concept is this. Immune cells are not separate from metabolism. They are deeply influenced by it.

What This Does Not Mean

This part is critical.

The human data from the 2026 study show immune activation signals, not long-term clinical outcomes. The fasting mimicking diet study was conducted in mice.

Cancer patients can be vulnerable to weight loss and malnutrition. Any dietary intervention during treatment must be discussed with an oncologist.

What these studies show is something more subtle but potentially powerful. They suggest that dietary timing and metabolic state can influence how the immune system responds to cancer therapy.

Should people just take isoleucine supplements?

No!!!

The study does not suggest that taking amino acid supplements will boost the immune system against cancer. The benefits seen in the research appear to come from the metabolic state created by short-term fasting, not from adding more isoleucine to the diet.

During fasting, the body naturally reshapes how nutrients are used and shared between cells, temporarily giving immune cells an advantage inside tumors. Simply consuming large amounts of isoleucine would not recreate this balanced biological response and could potentially feed both healthy and cancer cells.

It’s important not to misinterpret these findings. This research does not mean:

❌ Amino acids are a cancer treatment
❌ More nutrients automatically strengthen immunity
❌ Diet hacks can replace medical therapy

The discovery is about timing and metabolism, not supplements.

At this stage, fasting strategies are still being studied and should only be considered under medical supervision during cancer treatment.

A Bigger Picture

For decades, nutrition in cancer care has focused primarily on preventing weight loss and maintaining strength. That remains essential.

But we are entering a new era where researchers are asking more precise questions. Not only what patients should eat, but also when they should eat. And how does that timing interact with advanced therapies like immunotherapy?

The 16-hour fasting study provides a mechanistic framework. It connects a practical fasting window to measurable changes in tumor metabolism and T cell function. It also provides early human immune data.

The fasting mimicking diet study expands the story. It suggests dietary restriction may both enhance tumor control and reduce certain toxic effects in preclinical models.

Neither paper is a final answer. But together they point toward a field that is rapidly evolving. Metabolic oncology is becoming more sophisticated. It is no longer about vague claims that fasting is healthy. It is about identifying specific molecular pathways and testing them carefully.

Where Research Goes Next

The next steps are clear.

Larger randomized human trials are needed to test whether structured fasting or fasting-like interventions improve clinical outcomes such as tumor response rates or survival.

Researchers will need to determine which patients might benefit and which should avoid such interventions.

Safety will remain central. The goal is not to push fragile patients into calorie restriction. It is to explore whether carefully supervised metabolic interventions can complement existing therapies.

The Take Home Message

I usually focus on the brain and aging, and fasting is a topic that comes up often in that research. The science is complex. Too much fasting can be harmful, too little may offer no benefit, and the effects can vary widely depending on genetics, sex, lifestyle, environment, and overall diet. There is no single approach that works for everyone.

Still, growing evidence suggests that carefully timed fasting may influence processes linked to aging and brain health. I came across these cancer studies while researching that broader question, and they stood out because they are very new and offer a different perspective on how metabolism can shape disease and treatment.

In upcoming pieces, I’ll return to the aging and brain side of this topic in more depth. I’m currently putting together a longer, evidence-based guide that will be shared first with paid subscribers, and I’ll share more details soon.

A 16-hour overnight fast enhanced immunotherapy responses in mice and was associated with stronger CD8-positive T cell activity in a small group of human cancer patients.

A fasting mimicking diet enhanced immunotherapy efficacy and reduced treatment-related cardiac inflammation in mouse models.

These findings suggest that metabolic state can shape immune responses inside tumors.

This is not a replacement for medical treatment. It is a glimpse into how diet and advanced cancer therapies may intersect.

The science is still early. But the direction is clear. The immune system does not operate in isolation. It responds to the metabolic environment we create.

And sometimes, something as simple as when we eat may turn out to matter more than we once imagined.

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