Exercise and the Brain

(Thought-Random)

How can you protect your brain as you get older?

The most effective approach to keeping your brain healthy with age turns out to be something you probably wouldn't expect: physical exercise. Neurons need a lot of support to do their jobs correctly, and problems with an aging circulatory system can reduce the blood supply that brings oxygen and glucose to your brain. Regular exercise, of the type that elevates your heart rate, is the single most useful thing you can do to maintain your cognitive abilities later in life.

Elderly people who have been athletic all their lives are much better at executive-function tasks than sedentary people of the same age. This relationship could occur because people who are healthier tend to be more active, but that's not it. When inactive people get more exercise, even in their seventies, their executive function improves in just a few months. To be effective, exercise needs to last more than thirty minutes per session and occur several times a week, but it doesn't need to be extremely strenuous. (Fast walking works fine.) The benefits of exercise seem to be strongest for women, though men also show significant gains.

How does exercise help the brain? There are several possibilities, all of which could contribute to the effect. In people, fitness training slows the decline in cortical volume with age. In laboratory animals, exercise increases the number of small blood vessels (capillaries) in the brain, which would improve the availability of oxygen and glucose to neurons. Exercise also causes the release of growth factors, proteins that support the growth of dendrites and synapses, increase synaptic plasticity, and increase the birth of new neurons in the hippocampus. Any of these effects might improve cognitive performance, though it's not known which ones are most important.

Beyond normal aging, exercise is also strongly associated with reduced risk of dementia late in life. People who exercise regularly in middle age are one-third as likely to get Alzheimer's disease in their seventies as those who do not exercise. Even people who begin exercising in their sixties can reduce their risk by as much as half. See you at the gym!

Excerpted from "Welcome to Your Brain" by Sandra Aamodt and Sam Wang. Copyright (c) 2009, reprinted with permission from Bloomsbury USA.