As brains age, normal wear and tear starting in middle age causes them to process information more slowly, which means it takes longer to make judgments and grasp complex information.
The key to keeping intellectually sharp as we age may not be mental gymnastics, as commonly recommended, but real gymnastics. A number of earlier studies showed that elderly people who take up aerobic exercise show improved cognitive function after a few months, says Arthur Kramer of the University of Illinois, Urbana: Their working memory is better, they are nimbler at switching between mental tasks, and they can screen out distractions better than people who did not get exercise training.
As little as three hours a week of aerobic exercise increased the brain's volume of gray matter (actual neurons) and white matter (connections between neurons), they report in the November 2006 issue of the Journal of Gerontology: Medical Sciences. "After only three months," says Prof. Kramer, "the people who exercised had the brain volumes of people three years younger."
"This is the first time anyone has shown that exercise increases brain volume in the elderly," says Dr. Kramer. "It suggests that aerobic exercise can stave off neural decline, and even roll back some normal age-related deterioration of brain structure."
Source: The Wall Street Journal, November 16, 2006