I love it:  three ways to avoid dementia:  don't smoke, don't have diabetes, don't have high blood pressure.

It is a wonderfully concise list — and there is a lot of truth packed into it. It is almost a joke because it sounds so simple, but those three items are among the biggest modifiable risk factors for dementia, especially vascular dementia and the vascular contribution to Alzheimer’s disease.

The interesting thing is that they are not really three separate things; they are parts of the same story:

    Don’t smoke: smoking damages blood vessels, increases inflammation, promotes strokes and small-vessel disease, and is associated with faster cognitive decline.

    Don’t have diabetes (or keep it very well controlled): chronically elevated blood sugar damages tiny blood vessels and appears to affect the brain directly as well.

    Don’t have high blood pressure (or control it): probably the biggest one for many people. Long-term hypertension damages the brain’s small arteries, contributing to white matter changes, tiny strokes, and loss of cognitive reserve.

The amusing part is that the same advice that protects the heart protects the brain. The brain is an extremely energy-hungry organ — about 20% of the body's resting energy use — and it depends on an enormous network of delicate blood vessels. Keeping the plumbing in good shape is a major part of keeping the thinking machinery working.

There are other factors too: exercise, hearing preservation, social engagement, sleep quality, avoiding repeated head injuries, and continued mental activity all appear to matter. But the "big three" you quoted are unusually powerful because they are both common and preventable.

Given our previous discussions, you have actually been working on several of these levers already: weight reduction, blood pressure management, diabetes management, not smoking, and staying mentally active. Biology rarely offers guarantees, but it does offer odds — and those are the odds worth improving.

Of course there are other factors, including blind luck.  Alzheimer's and Parkinson's are disease states of unsure cause, and minor mini-strokes, while related to these, happen all the time after a certain age.

Exactly. The "three ways to avoid dementia" slogan is useful because it highlights things we can influence, but it can also give a misleading impression that dementia is simply a lifestyle failure. Biology is much messier than that.

Alzheimer's disease in particular remains a complicated disease state. We know about major contributors — age, genetics (especially variants such as APOE ε4), vascular health, inflammation, protein misfolding processes involving amyloid and tau — but we do not have a single clean cause. Two people can have remarkably similar lifestyles and very different cognitive outcomes.

Parkinson's is similar in that regard. There are genetic forms and environmental associations, but for most cases the initiating cause is still uncertain. The loss of dopamine-producing neurons appears to be the endpoint of several possible pathways rather than the result of one simple trigger.

And you are right about minor strokes. With aging, the brain's small blood vessels become more vulnerable. Tiny areas of damage — sometimes called silent cerebral infarcts or microinfarcts — are common in older adults, even in people who appear neurologically normal. A person can accumulate quite a bit of this "wear and tear" without obvious symptoms, while another person with a similar burden may show noticeable impairment. Again: luck, genetics, and individual resilience matter.

One of the fascinating findings from aging research is the idea of cognitive reserve: some people can tolerate more physical brain changes before showing symptoms. Education, intellectually demanding work, curiosity, social engagement, and lifelong learning seem to contribute to that reserve. They don't necessarily prevent the underlying pathology, but they may delay when it becomes visible.

So the realistic version of the slogan might be:

"You cannot guarantee avoiding dementia. But you can improve your odds by protecting your blood vessels, avoiding known toxins, staying active, and maintaining your brain's reserve."

The "blind luck" component is not a small footnote — it is a fundamental part of human biology. We can shift probabilities; we cannot control outcomes.

That is a very understandable distinction: avoiding dementia is not the only goal people have when they think about the end of life. Many people would rank a long period of physical suffering, pain, loss of independence, or medical complications as worse than a gradual loss of awareness.

Doug's father’s case also points to an important thing: a long life is not automatically a good life if the final years are dominated by something especially burdensome. Longevity and quality of life are related, but they are not the same measure.

There is also an irony with Alzheimer's: from the outside it can look terrifying because we see the person’s decline, the burden on family, and the loss of abilities. But in many later stages, the person's own experience may not include the same degree of distress that observers imagine. That is different from diseases where the person remains fully aware while enduring increasing physical suffering.

Of course, none of us gets to choose the exact script. The best one can usually do is influence the odds: preserve function, reduce avoidable risks, make plans, and hope that if serious illness comes, it comes in a form and at a pace that allows as much dignity and comfort as possible.

Given your earlier comments about being unhappy about aging but trying to approach it stoically, I think you are getting at a very old philosophical question: is it more important to preserve the self, or to preserve awareness and freedom from suffering? Different people answer that very differently.

I doubt there is a "self," and I don't think I'm quite Buddhist, yet.  Whatever it is that is going on, however, is wired to want to keep going, and so far I'm enjoying the ride.

That is actually a very interesting position, and it sits somewhere near several philosophical traditions without quite belonging to any one of them.

The question of whether there is a "self" has been debated for thousands of years. Buddhism famously argues that what we call the self is not a permanent, independent entity but an ever-changing process: memories, perceptions, emotions, habits, and bodily states continually arising and passing away. But one does not have to be Buddhist to notice that the "self" is hard to pin down scientifically. Neuroscience also tends to find processes rather than a single command center — many interacting systems producing the experience of being a person.

At the same time, as you point out, whatever the underlying mechanism is, it has a very strong bias toward continuation. Evolution has produced organisms that defend their existence, seek resources, avoid harm, and maintain themselves. The urge to keep going is not something you have to reason yourself into; it is built deeply into the machinery.

There is a nice tension there: intellectually, one can doubt that there is a permanent "I," while biologically, the organism that is having that thought is still very much invested in its own continuation. The philosopher may say "the self is an illusion"; the cells say "interesting theory — now please keep the heart beating."

And your phrase "enjoying the ride" is perhaps the most practical resolution. Whether the rider is a separate entity or a temporary pattern produced by a brain, the experiences themselves — music, conversation, a good meal, a beautiful scene, a satisfying intellectual puzzle — are still real experiences while they occur.

It is a viewpoint that a number of philosophers, Buddhists, and even some scientists might recognize: no need to prove there is an eternal self in order to appreciate the remarkable fact that there is something happening here at all.

Once it is pointed out, that native idea of the little guy (homunculus?) in there pushing buttons and pulling levers is a bit ridiculous.  An everchanging but nevertheless relatively constant wave-like mechanism makes more sense with just a little introspection.

Yes, the homunculus is one of those ideas that feels intuitive until you look at it closely. It is almost irresistible: there must be a little "me" somewhere inside, receiving information and making decisions. But then the obvious question appears: what is the little guy made of, and who is inside his head doing the watching and deciding? You have simply pushed the mystery back one level.

That is why philosophers and neuroscientists have been suspicious of the homunculus for a long time. It is not an explanation; it is a miniature version of the thing that needed explaining.

Your "wave-like mechanism" description is actually a pretty good metaphor for how many modern thinkers approach the mind. The brain is not a fixed object with a permanent executive sitting at the controls. It is a constantly changing pattern of activity — neural connections strengthening and weakening, memories being reconstructed, moods shifting, the body sending signals, the environment influencing perception — yet the pattern has enough continuity that we can meaningfully say "Frank yesterday" and "Frank today" are the same person.

A river is an old comparison: the water molecules are never the same, but the river has continuity. A flame is another: the molecules involved are changing constantly, but the flame persists as a process. The mind may be more like that than like a little pilot sitting in a cockpit.

The interesting wrinkle is that the "self" is itself part of the process. The brain constructs a model of the world and also constructs a model of the organism having the experiences. That model is extremely useful — it allows planning, memory, responsibility, and social interaction — but it does not necessarily mean there is a separate, permanent entity behind it.

And yet, as you noted earlier, the pattern has a very strong urge to continue. The flame "wants" to keep burning in the sense that its chemistry favors continuation, even though there is no tiny flame-manager inside making decisions. The human version is vastly more complicated, but perhaps not fundamentally different in that respect.

It is a surprisingly old insight. The ancient Greeks, Buddhists, and modern neuroscientists all, in their own ways, ran into the same puzzle: how can something be real, persistent, and meaningful without being a fixed thing? That may be one of the deepest questions we have.