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Physical exercise sharpens the brain

(This article was first printed in the July, 2003 issue of the Harvard Women's Health Watch. For more information or to order, please go to http://health.harvard.edu/women.)

Scientists already know from laboratory experiments that rodents who spend a lot of time running in exercise wheels have better brains than their layabout lab mates. But until now, we've had no physiological proof that fitness improves the human brain. In the first study of its kind, scientists at the University of Illinois at Urbana-Champaign scanned the brains of 55 subjects (more than half of them women), ages 55-79, and measured their maximal oxygen uptake (a gauge of aerobic fitness) during walking and treadmill tests. Participants ranged from sedentary to those in peak-performance fitness.

The results, published in the February 2003 Journal of Gerontology showed that physically fit subjects had less age-related brain-tissue shrinkage than less active subjects. Using magnetic resonance imaging, the researchers saw clear differences in the frontal, temporal, and parietal regions of the brain (see illustration). The tissues affected are crucial to memory, learning, and cell communication.

In a related study, the researchers analyzed data from 18 controlled studies that investigated the effects of aerobic fitness training on cognitive ability in women and men ages 55-80. They found that exercise had clear but selective benefits (Psychological Sciences, March 2003). The effect was greatest for executive control functions, such as attention, organization, and planning. Programs that combined strength training with aerobic exercise were more effective than aerobic training alone. The researchers also found that exercising less than 30 minutes per session had very little impact on cognitive function.