Two large studies -- one on men and the other on women -- reported in the Journal of the American Medical Association found that elderly people who walked were more likely to maintain cognitive function. And the more they walked, the better.
The study of women looked at more than 16,000 participants, aged between 70 to 81, in the Nurses' Health Study. It found those who regularly reported engaging in physical activity -- even walking a mere 1.5 hours a week -- had a higher level of cognitive function and less cognitive decline after 10 years. The most active had a 20 percent lower risk of cognitive impairment than the least active.
The study of 2,257 elderly Japanese-American men in Hawaii found that those who walked less than a quarter of a mile per day were nearly twice as likely to develop dementia and Alzheimer's disease, compared to men who walked more than two miles a day. The men were 71 to 93 years old.
"One hypothesis is that cardiovascular well-being bodes well for mental well-being," said Jennifer Weuve, a research fellow at the Harvard School of Public Health and author of the study on women. "The linkage is simply that if the vessels that supply the brain are in good shape, and the heart is in good shape and you don't have high blood pressure, your brain is better off."
"Women who performed a moderate amount of activity, on the order of walking two to three
And women who walked six or more hours per week saw even less decline in their cognitive function, she said. "This is good news because walking is a relatively easy way for people to preserve their learning, memory and attention."
Some researchers suspect walking may help the brain by encouraging the growth and survival of brain cells. Weuve says that the positive effects of walking were seen in older women regardless of their particular age, health habits or general health status.
Work in rats and mice has also found higher rates of physical activity are associated with higher levels of factors that promote growth and survival of brain cells, Weuve said, adding, "Both may be relevant."
Robert Abbott, a professor of biostatistics at the University of Virginia Health System who is a co-author of the study on men in Hawaii, noted that while his study did not prove a direct cause-and-effect relationship between walking and cognitive function, t indicated a very strong association.
"Walking tends to come with an overall healthier lifestyle. People who are more physically active are less likely to make a transition into disease states that have a more direct relationship with dementia, such as diabetes."
Still, he said, people who are physically active are "biologically younger" by two to three years than those who do not.
