Thankfully, these days the posture in health and wellness isn’t to wait for symptoms to show up before taking action. It’s to live in a way that prevents disease, decline, and dysfunction. And to act on information years before anything hurts or becomes a problem.

Brain health has been the hardest place to apply that logic. Everything else seems to come with a number and a lever. You track ApoB and adjust. You watch fasting glucose and adjust. You can’t really do that with your brain. The advice was to stay social, sleep well, and do the crossword. It isn't wrong, but it isn't a protocol, and there was no way to know if any of it was working.

Alzheimer's disease was the one that most needed that number and lever, and it had neither. It's also scaling: roughly 7 million Americans have it today, projected to reach about 14 million by 2060, largely because the population is aging and more people are living into the years when dementia is common.

It is also (on paper) the disease where the prevention logic should apply most cleanly, because it starts 15–20 years before anyone notices a symptom. That's a very long runway. For most of the last two decades, almost nobody was using it. The money, the trials, and the attention went to treating people who were already sick. Results were modest at best.

That has genuinely started to shift, and the last 18 months have been the most interesting stretch this field has had. There is now a blood test that reads the disease process a decade early. There is a large randomized trial showing a structured lifestyle program measurably protects cognition. There is a serious, funded argument that Alzheimer's is partly a metabolic disease, along with a major trial result that complicates it.

So that's what we're getting into below: what's real, what's overstated, and where we’re going.

What Exactly Is Alzheimer’s Disease?

Alzheimer's is defined biologically, not just by symptoms. What happens is that two proteins start to misbehave. Amyloid beta begins clumping into plaques outside brain cells, often 15–20 years before anyone notices a memory problem. Then there’s tau, a protein that normally helps hold neurons together. It starts to detach and twist into tangles inside them. And while amyloid gets most of the attention, tau actually tracks much more closely with symptoms, which may help explain why drugs that target only amyloid have been somewhat underwhelming.

But amyloid and tau are just part of the story. There’s a whole network of other things happening too, including inflammation in the brain, problems with blood flow, changes in how the brain produces and uses energy, and possibly a reduced ability to clear out proteins and other waste. Increasingly, Alzheimer’s looks less like one thing going wrong and more like several problems feeding into one another. And that mix may be different from person to person.

Alzheimer's is a cascade with multiple entry points, and by the time you can diagnose it, several of them are already open.

One term worth knowing is P-tau217, a form of tau that can now be measured with a simple blood test. It’s emerged as one of the most accurate blood-based markers we have for Alzheimer’s, potentially picking up changes in the brain before clear symptoms appear. And that’s a big deal. Until recently, detecting those changes often meant an expensive PET scan or a spinal tap. A blood test could make it much easier to identify Alzheimer’s earlier, and make testing far more accessible.

What About APOE4?

If you've done a genetic screening or a longevity panel, you may already know your APOE status, and it may be why you're reading this.

APOE comes in three versions. E3 is the common version, E2 appears protective, and E4 is the strongest common genetic risk factor for late-onset Alzheimer's. One copy raises risk roughly 3.5 times. Two copies, which about 2% of people carry, raise it roughly 15 times.

A 2024 Nature Medicine study of more than 10,000 people found that nearly everyone with two copies of APOE4 eventually showed the biology of Alzheimer’s, with biomarkers beginning to rise around age 55 and symptoms typically appearing around 65. The researchers went so far as to argue that having two copies should be considered a genetic form of Alzheimer’s rather than simply a risk factor. That idea is still debated, so I wouldn’t treat it as settled science.

There’s also a practical consideration. APOE4 carriers have a higher risk of ARIA, the brain swelling and bleeding that can occur with anti amyloid drugs, which can affect treatment decisions.

But here’s the part that might matter most: in the U.S. POINTER trial, the benefits of lifestyle intervention were there regardless of APOE4 status. Your genes may change where you start. They don’t appear to change whether the work is worth doing.

Alzheimer’s Finally Has a Biomarker

In May 2025, the FDA cleared the first blood test for Alzheimer's pathology, the Lumipulse P-tau217/beta-amyloid ratio. From a normal blood draw, it can detect the biological signs of Alzheimer’s with remarkable accuracy. Its positive predictive value is 92% and its negative predictive value is 97%. Until very recently, getting that kind of information meant a PET scan or a spinal tap.

Then, at this year's Alzheimer's Association conference in London, two follow-on results were shared.

The first looked at more than 1,300 patients in Sweden. When family doctors were given the results of the blood test, they correctly diagnosed Alzheimer’s 93% of the time—essentially the same as specialists, who were right 94% of the time. Without the blood test, those same family doctors were right just 65% of the time. That’s a pretty extraordinary difference from a simple blood draw.

But the second study is the one that really changes the prevention conversation. Researchers followed roughly 2,700 cognitively healthy older adults for a decade. Among people with very high P-tau217, an estimated 78% developed cognitive impairment within ten years, and about 33% did within five.

The comparison researchers keep making is to cholesterol. You feel perfectly fine, but a number in your blood can tell you something about where your health may be headed years from now.

But the cholesterol comparison isn’t perfect. We know what to do when someone’s LDL is high. With P-tau217, we’re not there yet. A high number may tell you that Alzheimer’s is developing years before symptoms appear, but we don’t yet have a proven way to intervene and change where that person is headed.

Current Alzheimer's Association guidance recommends these tests only for people already experiencing memory or thinking problems. But that's a real change on its own. If you or a parent is having genuine cognitive symptoms, the question of whether it's Alzheimer's can now be answered with a blood draw at a primary care office, by a doctor who two years ago would have been guessing, or making a specialist referral with a months-long wait. Getting the answer right matters, because a third of what looks like Alzheimer's is something else, some of it treatable.

Type 3 Diabetes

You may have heard AD being called “Type 3 diabetes.” But that is not a diagnosis, not a billing code, and not recognized by the American Diabetes Association or any other major body.

It is a shorthand for something real, though: in Alzheimer’s disease, the brain often shows problems with insulin signaling and energy use.

Insulin is best known for helping regulate blood sugar in the body. But it also has important jobs in the brain, where it helps support communication between neurons and cellular maintenance. In Alzheimer’s brains, researchers have found signs that this system is not working normally: weaker insulin and IGF signaling, changes in insulin receptors, and disruption of IRS-1, a protein that helps carry insulin’s message inside cells.

At the same time, the brain becomes less effective at using glucose, its main fuel. That can leave neurons underpowered and vulnerable. It may also worsen inflammation, oxidative stress, amyloid buildup, and tau changes.

That is where the “Type 3 diabetes” label comes from. It captures the idea that Alzheimer’s has a metabolic dimension, even in people who do not have Type 2 diabetes. But the label can mislead if taken literally. Alzheimer’s is not simply diabetes of the brain, and insulin does not control brain glucose use in exactly the same way it controls glucose uptake in muscle and fat.

The big unanswered question is whether disrupted brain insulin signaling helps cause Alzheimer’s, develops because of Alzheimer’s, or becomes part of a vicious cycle once the disease is underway. The honest answer? We don’t yet know. What is clear is that brain metabolism is not a side note in Alzheimer’s. It is part of the story.

GLP-1 and Alzheimer’s Disease

If problems with insulin signaling help drive Alzheimer’s, could a drug that improves metabolism slow the disease?

That was the hope behind two large trials called evoke and evoke+. Together, they enrolled 3,808 people ages 55–85 with amyloid-confirmed early Alzheimer’s disease. Participants took oral semaglutide (the same GLP-1 drug class used for diabetes and weight loss) or a placebo, for up to three years.

The result was clear: semaglutide did not slow clinical progression. Across measures of memory, thinking, daily function, and overall disease severity, people taking the drug did no better than those taking placebo.

But it is not the final word on metabolism and Alzheimer’s. Semaglutide is not a direct, complete repair of brain insulin signaling, and the trials began after participants already had mild cognitive impairment or mild dementia due to Alzheimer’s. By then, amyloid, tau, inflammation, vascular changes, and neuron loss may already be feeding one another.

The more intriguing research comes from large healthcare databases. In those observational studies, people taking GLP-1 drugs have appeared to have lower rates of dementia than people taking some other diabetes medications—and sometimes by a lot. Across studies, the apparent relative reduction ranges widely, from roughly 40% to 70%, depending on the drug, comparison group, and population studied. Some analyses suggest the association may be strongest among people with obesity or higher BMIs.

That is encouraging, but it’s not proof that these drugs prevent dementia. People prescribed one diabetes medication rather than another can differ in ways that also influence cognitive risk: body weight, blood-sugar control, cardiovascular disease, kidney function, healthcare access, and how often they interact with the medical system. Even sophisticated statistical adjustments cannot remove every one of those differences.

That is why PROTECT-Cog matters. Announced in London in July 2026, it’s a $100 million global trial asking whether adding a GLP-1 drug or a similar metabolism-targeting treatment to a structured lifestyle program can reduce cognitive decline, mild cognitive impairment, and dementia in at-risk older adults. Participants will be followed for three years.

The design is telling. The drug is not being treated as a replacement for the basics. The foundation is a U.S. POINTER–style program built around physical activity, nutrition, cognitive stimulation, and regular attention to cardiovascular and other health risks. The trial will compare a more intensively coached version of that program with a lighter-touch version, while also assessing what happens when a metabolism- and immune-targeting drug is added

That does not mean GLP-1 drugs prevent dementia. It means researchers are finally testing whether improving metabolic health before symptoms appear can add something meaningful to the lifestyle measures we already know matter.

Alzheimer’s Prevention in 2026

There is currently no pill or protocol proven to prevent Alzheimer's disease.

It’s worth being precise about why. The strongest lifestyle trials measure cognitive performance over two or three years, not whether participants eventually develop dementia. Proving the second would take a decade or more, and nobody has done it. But there is strong evidence that these programs protect thinking and memory, and good reason to believe that matters downstream.

The 2024 Lancet Commission estimates roughly 45% of dementia cases worldwide are potentially preventable by addressing 14 modifiable risk factors across the life course, with midlife as the highest-leverage window.

The factors include:

• Hearing and vision loss
• High LDL cholesterol
• Hypertension
• Diabetes
• Obesity
• Smoking
• Excess alcohol consumption
• Physical inactivity
• Depression
• Social isolation
• Head injury
• Air pollution
• Education earlier in life

What follows is an inventory of what that actually means in practice, sorted by how much weight the evidence can hold.

Tier 1: The Protocol That Beat a Control Group

U.S. POINTER researchers enrolled 2,111 adults ages 60–79 who had risk factors for cognitive decline. Everyone received a program built around exercise, a brain-healthy diet, cognitive challenge, social connection, and cardiovascular health. One group was mostly self-guided; the other received coaching, clear goals, regular check-ins, and peer support.

The structured version, which included coached goals, peer support, and accountability, produced even greater benefits, equivalent to roughly 1–2 years of cognitive advantage, according to the researchers.

The benefit held regardless of sex, ethnicity, APOE4 status, or baseline heart health. The structured arm also reduced frailty, sleep apnea, and improved blood pressure control. And neuroimaging found the intervention protected against the effects of existing tau buildup, with amyloid burden failing to predict who benefited. People already accumulating pathology got the same gains. It was not too late for them.

This is the actual prescription the structured arm followed:

• Moderate-to-intense aerobic activity, 30–35 minutes, four times a week
• Strength, flexibility, balance, and coordination work twice a week
• The MIND diet: leafy greens, berries, nuts, whole grains, olive oil, fish, with sugar and poor-quality fats limited
• Computerized cognitive training, 30 minutes, three times a week
• Regular monitoring of blood pressure, weight, and labs

The five items above are the recipe. The sixth ingredient was structure: 38 facilitated peer group meetings over two years, adherence tracked with real numbers, and periodic goal-setting with a clinician. The self-guided arm got the same recipe with six meetings and no coaching. The structured arm is the one that pulled ahead.

That model also replicated this year. LatAm-FINGERS, published in The Lancet, ran the program across 11 Latin American countries with local adaptations, and the structured arm showed 55% greater improvement in memory, thinking, and reasoning over two years.
The intervention is multidomain by design, so nobody can tell you which component did the work. The entire prescription is the finding.

But certain activities lend themselves to prevention. Tennis, dance, and martial arts may be unusually good “all-in-one” activities for brain health. Depending on how you do them, they can combine aerobic effort with coordination, rapid decision-making, learning new movement patterns, and social connection—the same broad ingredients that multidomain dementia-prevention programs try to build in separately.

The best exercise is often the kind that challenges both body and brain . . . and that you will keep doing.

Tier 2: The Newer Levers

Treat your metabolic numbers as brain numbers.
In 2024, high LDL cholesterol joined the Lancet Commission’s list of modifiable dementia risk factors. Blood pressure, blood sugar, diabetes, and cholesterol all matter because the brain depends on healthy blood vessels and a steady energy supply, especially in midlife, when many of these risks begin to shape the decades ahead.

Address hearing and vision.
Hearing aids and vision correction are not dementia treatments. But untreated sensory loss can quietly shrink a person’s world, making conversation, exercise, reading, driving, and social connection harder to maintain. In the strongest hearing-aid trial, ACHIEVE, a pre-specified subgroup of adults with higher cardiovascular and cognitive risk saw cognitive decline slow by 48% over three years with hearing aids and audiology support.

Vision deserves the same attention. Keeping the senses working helps people remain active, connected, and engaged with the world, and those are the conditions a resilient brain depends on.

Treat sleep as (non-negotiable) brain maintenance.
Sleep is when the brain consolidates memories, restores the networks that support attention and learning. It appears to increase clearance of metabolic waste, including proteins linked to Alzheimer’s. Chronic short, fragmented, or irregular sleep is associated with worse brain and cardiovascular health. But “more sleep” is not the goal; regular, restorative sleep is. If you snore loudly, stop breathing at night, or wake unrefreshed, consider evaluation for sleep apnea, which is both common and treatable.

Protect your head.
Repetitive head impacts are on the Lancet Commission’s dementia-risk list, and new data presented at the 2026 Alzheimer’s Association International Conference in London added to concern about soccer headers. Studies linked greater heading exposure and longer soccer careers with biomarkers of neural injury and tau accumulation. It’s worth considering if you or your kids play collision sports.

3 Things Worth Watching

The Shingles Vaccine

A natural experiment in Wales produced one of the more surprising dementia findings in recent years. Because vaccine eligibility depended on an arbitrary birthdate cutoff, researchers could compare otherwise similar adults who were just old enough to qualify with those who were not. Over seven years, vaccinated adults were about 20% less likely to receive a dementia diagnosis.

That does not prove that the vaccine prevents dementia. But the study design is stronger than a typical observational study; similar findings have appeared in Australia; and follow-up work suggested fewer mild cognitive impairment diagnoses and lower dementia-related mortality. It makes the idea that infections (or the immune system’s response to them) can influence dementia risk much harder to dismiss.

Intranasal Insulin

The idea is simple: deliver insulin through the nose, where some of it may reach the brain without substantially affecting blood sugar in the rest of the body. Small early studies were encouraging, but larger trials have been mixed. In the largest study, involving 289 people with mild cognitive impairment or Alzheimer’s dementia, intranasal insulin did not improve cognition or daily function overall; interpretation was complicated by problems with the delivery device.

Still, the idea is not dead. A 2025 imaging study showed that intranasal insulin reached multiple brain regions involved in memory, with different uptake patterns in people with early cognitive decline. The unanswered question is no longer whether the drug can get there. It is whether delivering it this way can meaningfully change the course of disease.

Peptides

The peptide-related approaches with substantial human trial data are GLP-1 drugs and intranasal insulin, both of which have produced more questions than answers so far.

But there is real promise in peptide science. Researchers are designing peptides that could interrupt harmful amyloid or tau interactions, protect vulnerable synapses, or reduce inflammatory signaling. Most of that work is still in cells and animal models, not proven human treatment.

The nearer-term opportunity may be delivery. Peptides can be engineered as “shuttles” that help larger medicines cross the blood–brain barrier, one of the central obstacles in treating brain disease. That could eventually make existing drugs more precise and effective, or open the door to entirely new ones.

The Bleeding Edge

These three ideas are not ready for patients, but they show where Alzheimer’s research may be heading.

Lowering tau production inside the brain.

Diranersen is designed to reduce the brain’s production of tau. In a phase 2 trial, it substantially lowered tau levels and showed signs of slowing cognitive decline, particularly at the lowest dose. But the trial missed its primary endpoint, and higher doses didn’t lead to better cognitive outcomes.

So this is far from proven. Still, it’s one of the first randomized trials to show that directly targeting tau may affect both the biology of Alzheimer’s and potentially its progression.

Editing the risk gene.

APOE4 is the strongest common genetic risk factor for late onset Alzheimer’s. Researchers have now used gene editing to essentially convert APOE4 into the lower risk APOE3 version in mice. This is still a long way from humans, with major questions around safety and actually delivering it throughout the brain. But the idea itself is fascinating: a genetic risk you’re born with may not always be something you’re stuck with.

Opening the blood–brain barrier on purpose.

Focused ultrasound can temporarily open the blood–brain barrier, allowing treatments that normally can’t reach the brain to get through. In a 2025 mouse study, researchers used it to deliver a CRISPR based therapy to the hippocampus, reducing expression of the Alzheimer’s risk gene APOE4 and its protein. It’s still very early, but it could help solve one of the biggest challenges in treating brain disease: actually getting the treatment where it needs to go.

The Bigger Picture

Alzheimer’s is complex. It is not one broken protein, one bad habit, or one number on a blood test. It is a slow, layered process involving amyloid and tau, but also blood vessels, metabolism, inflammation, sleep, sensory health, and the accumulated wear of aging.

That can sound discouraging, but the good news is that there is no single point at which the story is over. The things that protect brain health are mostly the same things that protect the rest of the body: move often, manage blood pressure and blood sugar, sleep well, stay connected, keep hearing and vision working, and give your brain reasons to keep learning.

None of this guarantees that someone will avoid dementia. Genes matter. Aging matters. Biology is not a moral scorecard, and risk is not destiny. But the goal is not simply to prevent a future diagnosis. It is to preserve what makes life feel full in the meantime: clear thinking, physical independence, close relationships, curiosity, and the ability to remain present in your own life.

But help, hopefully, is on the way.

Disclaimer: This newsletter is provided for educational and informational purposes only and does not constitute providing medical advice or professional services. The information provided should not be used for diagnosing or treating a health problem or disease, and those seeking personal medical advice should consult with a licensed physician.