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Avoiding Dementia: Fitness and Your Brain
By Steven K.
Feske*, M.D., Newsweek
September 29, 2005
People who take care of themselves may live longer, goes the couch potato's refrain-but why would they want to? Better to live hard and die young than hang around for an old age blighted by dementia. It's a seductive excuse-and a deeply misguided one. In truth, almost anything that raises your risk of heart disease-smoking, obesity, high blood pressure, elevated cholesterol-also increases your risk of forgetting your name. If you want to keep your brain humming for life, staying fit is job one.
How does heart-healthy living help preserve our mental faculties? First, it helps prevent the repeated minor strokes that often lead to dementia. The most common type of stroke is analogous to a heart attack: atherosclerotic plaques in the arteries feeding the brain suddenly rupture, causing clots that choke off needed blood flow. Atherosclerosis can trigger strokes even when it's confined to the arteries around the heart. Clots can form in an ailing heart, and then lodge in the arteries feeding the brain. Fortunately, a heart-healthy lifestyle protects arteries in both parts of the body. Diet and exercise can also help ward off high blood pressure, a risk factor both for atherosclerosis and for a second kind of stroke in which a weakened cerebral artery bursts to cause a brain hemorrhage.
Stroke isn't the only brain killer that a heart-healthy lifestyle may help you avoid. Mounting evidence suggests that diet and exercise can also help ward off Alzheimer's disease-in part by controlling inflammation. Alzheimer's involves the buildup of a sticky protein called beta-amyloid, which forms cell-killing plaques throughout the brain. And like the arterial plaques that cause heart attacks and strokes, these amyloid plaques are made worse by inflammation. Anything that elevates the inflammatory response may also speed the formation of amyloid plaques. That's another likely reason why controlling inflammation and other cardiac risk factors protects the brain as well as the heart.
Researchers are just beginning to study that hypothesis, but the possibilities are exciting. Statin drugs may well reduce the risk of dementia-both by lowering cholesterol and by reducing inflammation. Drugs that control diabetes and high blood pressure may also prove useful. We still lack definitive evidence on whether treating high blood pressure helps prevent cognitive decline, but several good studies find that it does. Aspirin may help, too. Researchers have reported that low doses appear to reduce stroke risk in women younger than 65, and in men older than 50 who have one or more cardiac risk factors.
The findings on diet and lifestyle are equally encouraging. There is no question that you can reduce your risk of atherosclerosis by eating a diet rich in fruits, vegetables and fiber, and low in saturated fats and trans fats. And as you'd expect, studies are now showing that the same diet reduces the risk of dementia. In a study published in August, researchers at the University of California, Irvine, tracked 579 people older than 60 for periods of up to 14 years and found that those who consumed the most folic acid-a B vitamin that abounds in leafy green vegetables-were the least likely to develop Alzheimer's. People who got at least 400 micrograms a day, whether from diet or from supplements, enjoyed a 55 percent reduction in risk. Other studies have shown similar benefits from regular, moderate exercise (30 minutes at least five times a week) and from maintaining a healthy weight. We don't yet know exactly how nutrition and exercise prevent Alzheimer's. Exercise may prevent chronic inflammation by keeping insulin levels in check. And folic acid may work partly by controlling the buildup of homocysteine, a potentially harmful byproduct of the protein in our diets.
Whatever the mechanisms, the take-home lesson is clear: what's good for your heart is good for your brain. So turn off the TV and go for a walk with a friend. You'll live longer that way-and you'll stay sharper, too.
*Feske is a neurologist at Harvard Medical School and Brigham & Women's Hospital. For more information about the heart-brain connection, go to health.harvard.edu/NEWSWEEK.
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