A woman I know, sixty-seven, a retired school librarian, told me last fall that she had started keeping a notebook in her purse. Not for grocery lists. Not for appointments. For words.
She had been mid-sentence at dinner with her daughter when the word “candelabra” disappeared. She knew exactly what she meant. She could see the object. She could describe it. But the word itself had stepped out of the room, and for eleven seconds that felt like three minutes, she stood in the space where it had been. Her daughter didn’t notice. She noticed. She went home and started the notebook. Every word she lost, dated, with context. She had been keeping it for four months when she told me about it. She laughed when she showed it to me, but it was not a laughing kind of laugh.
I tell you this because I think a version of this notebook exists, physically or mentally, for almost every person between sixty and seventy-five I have spoken to about cognitive health. The fear of dementia is the background noise of this age range. It is there when you walk into a room and forget why. It is there when a name you have known for thirty years takes a beat too long to arrive. It is there because almost everyone in this demographic has watched a parent or a friend or a neighbor go through Alzheimer’s disease or another form of dementia, and the watching was terrible, and the possibility that it could happen to them is the thing they think about at two in the morning and don’t always say out loud.
I’m not going to dismiss this fear. It is based on something real. Dementia is common, it is devastating, and the research hasn’t yet produced a cure or a reliable way to prevent it entirely. If you are afraid, the fear makes sense.
What I’m going to do is sort through what we actually know. Because the fear, left unsorted, sends people to the supplement aisle, to the brain-training apps, to the omega-3 capsules, to whatever the internet served them this morning. Some of that is fine. Some of it is expensive and useless. And some of what actually has evidence behind it is so unglamorous that nobody is selling it to you, which is partly how you can tell it works.
Your brain runs on your cardiovascular system
The single strongest finding in dementia research over the past twenty years is not about the brain in isolation. It is about the heart.
Your brain consumes roughly twenty percent of your body’s blood supply. It is utterly dependent on healthy blood vessels to deliver oxygen and clear waste. When the cardiovascular system deteriorates, the brain feels it. Vascular dementia, the second most common form after Alzheimer’s, is caused directly by reduced blood flow to the brain. And even in Alzheimer’s disease, vascular health plays a significant modifying role. People with cardiovascular risk factors develop Alzheimer’s symptoms earlier and more severely than people without them.
This means that the things your doctor has been telling you about heart health for twenty years are, simultaneously, the most evidence-backed things you can do for your brain. Managing blood pressure. Managing cholesterol. Not smoking. Controlling blood sugar if you have diabetes or prediabetes. These are not brain-specific interventions. They are cardiovascular interventions that protect the brain because the brain can’t function without healthy vasculature.
Blood pressure in particular deserves attention. The research here is specific: uncontrolled hypertension in midlife and early older age is one of the strongest modifiable risk factors for later cognitive decline. The SPRINT MIND trial, published in 2019, found that intensive blood pressure control (targeting systolic pressure below 120 rather than below 140) reduced the risk of mild cognitive impairment. If your blood pressure isn’t controlled and you’re in your sixties, that’s not just a heart problem. It is a brain problem. Treat it as both.
Movement, and specifically aerobic movement
The evidence for aerobic exercise and cognitive health is strong enough that if it were a pharmaceutical, it would be the most prescribed drug in the country.
Regular aerobic activity improves cerebral blood flow, promotes the growth of new blood vessels in the brain, and increases the production of a protein called brain-derived neurotrophic factor, or BDNF, which supports the survival and growth of neurons. In clinical studies, older adults who engage in regular aerobic exercise show slower rates of hippocampal shrinkage (the hippocampus is the brain structure most involved in memory formation) and perform better on cognitive tests over time compared to sedentary controls.
This doesn’t require running marathons. Walking counts. The studies that show benefit are mostly looking at moderate aerobic activity, something that elevates your heart rate and keeps it there for thirty minutes, done consistently. Three to five times a week. The key word is “consistently.” A burst of activity followed by three weeks of nothing doesn’t produce the effect. The benefit accumulates over months and years of regular practice.
I walk or run six mornings a week. I do this because I like mornings and because I like moving and because the evidence says it is the single most useful physical thing I can do for my brain. I have never found a supplement that competes with it.
Sleep and the cleaning system you didn’t know you had
In 2012, researchers at the University of Rochester identified something they called the glymphatic system, a network of channels in the brain that clears metabolic waste, including amyloid, the protein that accumulates in the brains of people with Alzheimer’s disease. The significant finding was this: the glymphatic system is most active during deep sleep. Specifically, during slow-wave sleep, the spaces between brain cells expand by roughly sixty percent, allowing cerebrospinal fluid to flush through and carry waste products away.
This means that sleep isn’t merely rest for the brain. It is active maintenance. When you consistently get inadequate or fragmented sleep, the brain’s waste-clearance system operates at reduced capacity. The research linking chronic sleep disruption to increased amyloid accumulation is growing and is being taken seriously by the field.
I wrote at length in my last column about what happens to sleep architecture after sixty and what the evidence supports for improving it. The relevant point here is that protecting your sleep isn’t a lifestyle recommendation. It is, based on what we currently understand, a direct investment in your brain’s ability to clear the proteins associated with Alzheimer’s pathology.
If you are sleeping poorly and have been for years, that is worth addressing with your doctor. Not with a supplement. With a conversation about what is actually happening to your sleep and whether it can be improved.
The people around you
The relationship between social isolation and cognitive decline is strong enough that the 2020 Lancet Commission on dementia prevention listed social isolation as one of twelve modifiable risk factors for dementia. Loneliness and social disengagement are associated with faster cognitive decline and higher dementia risk in multiple large, long-term studies.
This isn’t because conversation is a brain exercise, though it is. It is because social engagement involves sustained attention, emotional processing, language production, memory retrieval, and the kind of complex cognitive work that keeps neural networks active. When people withdraw socially, whether through retirement, loss of a spouse, mobility limitations, or simply the slow contraction of a social circle over time, they lose a form of cognitive stimulation that is difficult to replace.
I mention this not to add guilt to isolation but to name it as a factor the research takes seriously. If your social world has gotten smaller in recent years, that is worth noticing.
Your hearing
This one surprises people, and it should be talked about more.
The 2020 Lancet Commission identified hearing loss as the single largest modifiable risk factor for dementia, accounting for more population-level risk than any other individual factor. Untreated hearing loss in midlife is associated with significantly accelerated cognitive decline. The ACHIEVE trial, published in 2023 in The Lancet, found that hearing intervention (primarily hearing aids) slowed cognitive decline by 48 percent over three years in a subgroup of older adults at elevated risk.
The mechanism is likely multifactorial. When you can’t hear well, you withdraw from conversation. You stop going to places where background noise makes it hard to follow. Your brain receives less auditory stimulation. The cognitive effort required to decode degraded sound signals pulls resources away from other processing. All of this compounds.
If you have been putting off getting your hearing checked because hearing aids feel like an admission of something, I would encourage you to reframe it. Hearing correction is, based on current evidence, one of the most impactful things you can do for your cognitive health. It isn’t vanity. It is neurology.
What doesn’t have strong evidence
I’ll be direct about this because the supplement and brain-training industries are spending a great deal of money to blur the line between preliminary findings and proven interventions.
Omega-3 fatty acid supplements (fish oil) have been studied extensively for cognitive benefit in older adults. The large, well-designed trials haven’t shown that omega-3 supplementation prevents or slows cognitive decline. There are studies with positive findings, but they tend to be smaller, shorter, or conducted in populations with existing deficiencies. Eating fish is fine. Paying for high-dose fish oil capsules as dementia prevention isn’t supported by the weight of the evidence.
Ginkgo biloba was tested in the Ginkgo Evaluation of Memory study, one of the largest randomized controlled trials conducted on a supplement for cognitive outcomes. It enrolled over three thousand adults over age seventy-five and followed them for six years. Ginkgo didn’t reduce the incidence of dementia or Alzheimer’s disease. The study was published in 2008 and the finding has held.
Phosphatidylserine, various B-vitamin formulations, coconut oil, turmeric, and the rotating cast of compounds marketed as “brain health” products have either not been tested in rigorous large-scale trials or have failed to show benefit when they were. I’m not saying these substances are harmful. Most aren’t. I’m saying the gap between “this showed something interesting in a petri dish” or “this helped in a small preliminary study” and “this prevents dementia in humans” is enormous, and the supplement industry lives in that gap.
Crossword puzzles, Sudoku, and brain-training apps are in a similar category. There is evidence that cognitive stimulation is good for the brain. There isn’t strong evidence that any specific commercial brain-training product prevents dementia. Doing puzzles may make you better at puzzles. Whether that transfers to broader cognitive protection is unresolved. I do the crossword most mornings because I enjoy it, not because I think it’s medicine.
The question you are actually afraid to ask
If you are noticing changes, here is what I want you to know.
Some cognitive change with age is normal. Word retrieval slows. Processing speed decreases. The name that used to arrive instantly now takes a beat. You walk into a room and forget why. These are common, documented, and in most cases aren’t dementia. They are the cognitive equivalent of the knee that takes a minute to warm up in the morning. Not ideal, not dangerous.
What is different from normal aging: getting lost in familiar places. Repeating the same question multiple times in a short period without remembering you already asked. Difficulty following the steps of a familiar recipe or a routine task you have done for years. Significant changes in judgment or decision-making that other people notice. Personality changes that aren’t explained by other factors.
If you are experiencing the second category, or if someone who knows you well has expressed concern, make an appointment with your primary care physician. Say this: “I have noticed some changes in my memory and thinking, and I would like to be evaluated.” Don’t minimize it. Don’t wait for the doctor to ask. Put it at the top of your list. A cognitive screening takes about ten minutes. It isn’t a diagnosis. It’s a starting point.
Early detection matters because some causes of cognitive symptoms are treatable. Thyroid dysfunction, medication side effects, depression, vitamin B12 deficiency, sleep apnea. These can all produce cognitive symptoms that look like early dementia and are not. Ruling them out is valuable. And if the evaluation does point toward something more serious, earlier knowledge gives you more time to plan, more access to clinical trials, and more ability to make decisions while you are still the one making them.
The woman with the notebook is still keeping it. She also started walking four mornings a week, got her hearing tested (mild loss in the left ear, now corrected), and had her blood pressure medication adjusted after learning it had been running high at her last two appointments. She didn’t need a supplement. She needed information and a doctor who would spend more than seventeen minutes with her.
The research on dementia prevention doesn’t offer a pill. It doesn’t offer certainty. What it offers is a short, specific, boring list: manage your blood pressure, move your body, protect your sleep, stay connected to people, and get your hearing checked. These aren’t exciting interventions. They won’t be featured on the cover of a magazine. They are also, at this moment, the best tools we have, and they are available to almost everyone, and most of them cost nothing.
I know that isn’t the answer anyone wants. But it is the answer the evidence gives, and I have spent my career trusting evidence over comfort. Your brain isn’t a mystery you need a special product to protect. It is an organ that runs on blood and oxygen and sleep, that thrives on connection and stimulation, and that asks from you the same things your cardiologist has been asking for years. The stakes are just higher than you realized, and now you know.
Questions to bring to your doctor if you are concerned about cognitive health:
- What is my current blood pressure, and is it where it should be for brain health specifically?
- Should I have a cognitive screening, given the changes I have noticed?
- When was my last hearing evaluation, and is it time for one?
- Are any of my current medications associated with cognitive side effects?
Carol Gifford spent fourteen years as a registered nurse, including six in hospital case management. She writes about health and medicine for people who want accurate information without the alarm or the sales pitch. She lives in Madison, Wisconsin.
