MONDAY, Dec. 27, 2004 (HealthDayNews) -- A small new European study adds to the growing body of evidence that exercise can stave off mental decline in older people.
The 290 participants, all men, were between the ages of 70 and 90 when the study began in 1990. They were asked about such physical activities as walking, gardening, bicycling, and sports.
Ten years later, the researchers found that the reduction in mental ability, as measured by a standardized test, was 2.6 times greater in the men who reduced their activity by an hour or more a day compared to those who maintained their activity level.
The loss of mental ability was directly related to a reduction in activity, the researchers found. The decline was 3.6 times greater in men with the lowest level of activity compared to those who were more active. No decline in mental ability was found in men who stepped up their physical activity.
The study results appear in the Dec. 28 issue of Neurology, the journal of the American Academy of Neurology.
The results are similar to those of a study done with younger American women, said Jennifer Weuve, a research fellow at the Harvard School of Public Health, who reported the results of that trial in September.
There were some differences between the two studies, Weuve said, such as the kind of activity that was performed. The European men did more bicycling -- two to three hours a week -- while "for our women, the primary activity was walking," she said.
The greatest difference was in age. The U.S. women Weuve studied were in their late 50s and early 60s, decades younger than the European men, "at an age when they were unlikely to be affected by a decline in cognition," she said.
One possible interpretation of the European study is that a loss of mental ability led to reduced physical activity, Weuve said. But the more likely explanation is that physical activity is good for the brain as well as the body.
"The evidence certainly points that way," she said.
There are two theories, not necessarily exclusive, to explain the beneficial mental effects of exercise, Weuve said. One is that physical activity increases the flow of blood to the brain, just as it improves circulation to the heart and the rest of the body. The other is that activity stimulates the growth of nerve cells in the hippocampus, the region of the brain involved in memory.
Whatever the explanation, "the risks of being active are fairly small," and the European study indicates that it's never too late to get benefit from physical activity, Weuve said.
Bill Thies, vice president for medical and scientific affairs at the Alzheimer's Association, said the new study "fits into a bigger body of evidence where virtually all the studies [involving exercise] point in the same direction."
It also fits in with the association's "Maintain Your Brain" campaign, which includes regular physical activity as an essential part of an individual's effort to stay alert, Thies said.
The Alzheimer's Association has more on the value of diet and exercise.