Mild, regular exercise, such as a few hours of walking per week, appears to help keep the mind sharp in old age, according to two studies released Tuesday.

In one report, researchers found that elderly men who walked at least 2 hours per day were significantly less likely to develop dementia over a 6- to 8-year period.

The other study showed that the more women exercise, the less likely they are to experience declines in learning and memory over a 2-year period, often early warning signs of dementia.

“If you walk a little, you get a little benefit,” study author Dr. Robert D. Abbott of the University of Virginia Health System in Charlottesville told Reuters Health. “If you walk a lot, you get a bigger benefit.”

Abbott added that walking and other light forms of exercise have been linked to a number of health benefits, such as a lower risk of cancer and heart disease, and greater longevity.

“It’s interesting that this health benefit extends to other diseases, including dementia,” he noted.

Both reports appear in this weeks’ issue of the Journal of the American Medical Association.

Abbott and his colleagues reviewed information about physical activity collected from 2,257 men of Japanese ancestry living in Hawaii, who were between the ages of 71 and 93 years old in the early 1990s. The researchers followed them for up to 8 years and noted who developed dementia.

The authors found that men who walked less than one quarter of a mile per day were 80 percent more likely to become demented, compared with men who said they logged at least 2 miles of walking time each day. Men who walked more than one-quarter mile each day but less than 2 miles also showed a slightly higher risk of dementia compared with men who walked the most.

In addition, during the first evaluation, men who were able to walk 10 feet in 3 seconds or less - an indication of physical fitness - showed a slightly lower risk of developing dementia during the following years.

Abbott said that walking is likely not the only form of exercise that benefits older men. For those who are unable to walk, any form of physical activity may help, he noted.

In the second report, Dr. Jennifer Weuve and her colleagues asked more than 18,000 women between the ages of 70 and 81 to complete tests of learning and memory, then repeated the same tests 2 years later.

They found that women who were more active were more likely to do well on the tests of mental functioning. Specifically, women who exercised the equivalent of walking at an easy pace for at least 1.5 hours each week scored higher on the tests than women who spend less than 40 minutes per week at the same activity level.

“More walking is associated with even more benefits for the mind,” said Weuve, who was based at both the Harvard School of Public Health and Brigham and Women’s Hospital in Boston at the time of the study.

She added that no one is exactly sure why exercise may help the brain. Some experts believe that activity helps the brain by keeping blood vessels healthy. Physical activity may also help brain cells directly, Weuve noted.

SOURCE: Journal of the American Medical Association, September 22/29, 2004.