Staying Sharp: Can You Prevent Alzheimer's Disease?

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One of the top ways to take care of your mind, it turns out, is to make sure your heart is performing at its best. And there's nothing like physical activity to promote cardiac fitness. For some people, that will mean participating in an aerobics class three or more times a week. For others, walking as fast as they can half an hour a day most days of the week will do the trick. In fact, all other things being equal, people who engage in a wide variety of physical activities—like walking and biking and dancing and swimming—seem to be better protected against cognitive decline than those who don't.

The research linking heart and brain health is so strong that as you continue reading this article, you may get the feeling that you've stumbled into a story about how to prevent cardiac disease. But if fear of a heart attack isn't enough to get you to pamper your ticker, fear of senility just might. So think about doing your heart and your head a favor. If you smoke, quit. Get your cholesterol levels and blood pressure checked, and if they are high, get them treated. If you have diabetes, do everything you can to keep it under control. Eat at least five servings of fruits and vegetables a day, consume fish once or twice a week and cut down on the amount of trans and saturated fat in your diet. The effects appear to be cumulative. A study published in August found that folks with three or more major cardiovascular risk factors—for example, hypertension, diabetes and current smoking—were more likely to develop Alzheimer's disease as well.

Why is cardiovascular fitness so important to cognitive health? Researchers used to think it was all about making sure that plenty of oxygen-rich blood made it to the brain. Now they are starting to suspect there may be more to it. In laboratory animals, at least, exercise also seems to stimulate the body's production of certain molecules called growth factors, which help nerves stay healthy and keep functioning. "We don't understand a lot about why this happens," says Arthur Kramer, a researcher at the University of Illinois who uses brain scans to study the effects of exercise. "But we're learning more about that."

A healthy cardiovascular system may even, to some extent, compensate for tiny defects in the brain. Doctors have long known that suffering one or more strokes, which interrupt the flow of blood to the brain, increases the likelihood of dementia. They assumed that Alzheimer's disease was a completely unrelated problem. In fact, a long-running study of a group of nuns who agreed to donate their brains when they died has found that isn't necessarily the case. About a third of the nuns whose brains at autopsy showed clear signs of the plaques and tangles associated with Alzheimer's disease had exhibited normal memory and cognitive function until the day they died. The difference: the blood vessels in their brains were in great shape.

That doesn't mean those women wouldn't eventually have developed dementia had they lived long enough. But the study suggested to a lot of physicians that good vascular health may make it easier for a brain with incipient Alzheimer's to work around the plaques and tangles in its midst.