TUESDAY, Sept. 21, 2004 (HealthDayNews) -- Walking reduces the risk of dementia and boosts mental function, two new studies show.
Both reports touting the health benefits of regular strolls appear in the Sept. 22/29 issue of the Journal of the American Medical Association.
In one study, Robert D. Abbott, a professor of biostatistics at the University of Virginia School of Medicine, and his team evaluated more than 2,000 men aged 71 to 93 who were part of the Honolulu-Asia Aging Study. The researchers asked the men about their typical daily walking and then tested them for dementia.
Other studies have found physical activity may reduce the risk of dementia, Abbott said, but whether the association holds true for low-intensity activities such as walking has not been known. Dementia describes a group of symptoms related to brain function changes, such as memory problems and behavior changes.
Walking does indeed lower dementia risk, the researchers discovered. "Those who walked less than a quarter mile a day were nearly twice as likely to develop dementia as those who walked more than two miles a day," Abbott said.
"These were all retired men," he said. And the walking wasn't necessarily done in a formal setting such as a gym, he added: "They could be walking to the grocery, or walking for another errand."
The distance walked by the men was assessed from 1991 to 1993. Exams to test their neurological functioning were done from 1994 to 1996 and again from 1997 to 1999.
In the second study, Jennifer Weuve, a research fellow at the Harvard School of Public Health, and her colleagues surveyed more than 18,000 women, aged 70 to 81, who were part of the long-running Nurses' Health Study. In telephone interviews conducted from 1995 to 2001, the women were tested for verbal memory, attention, and other gauges of cognitive functioning. They were asked about their typical physical activity, and the researchers converted that activity into what it was in terms of miles walked.
"The more active women had better cognition," Weuve said.
Among women who put in the highest of five levels of activity -- the equivalent of six or more hours of weekly walking at an easy pace -- there was a 20 percent lower risk of cognitive impairment compared to women in the lowest level of activity -- the equivalent of walking less than two hours a week at an easy pace.
At two hours of walking a week, the health benefits first became apparent. "Memory, attention and learning ability may be preserved by walking two to three hours a week at an easy pace," said Weuve, defining an easy pace as taking about 20 or 30 minutes to cover a mile. For those who walk at a pace of 16 to 20 minutes per mile, about one and a half hours a week would do it, she said.
Ideally, she said, walking six hours a week at an easy pace -- or expending the same amount of energy at another exercise -- is associated with the most benefits.
Physical activity benefits the cardiovascular system, Weuve said, and "there is some evidence that better cardiovascular health is related to better cognitive function. Physical activity also appears to have a direct effect on the brain itself," she said. "It appears to promote the production of chemicals in the brain, called nerve growth factors, that improve the brain cells' survival and growth."
Abbott agreed: "Those who are more physically active tend to have a better cardiovascular risk profile," he said. "And maybe that helps protect against dementia."
The findings come as no surprise to Dr. Gary Small, director of the UCLA Center on Aging, who found in one of his recent studies that lifestyle changes such as regular exercise can boost memory.
"There is evidence at least in the short run that these kinds of lifestyle changes do have a significant effect on brain function, memory ability and different health measures that predict longevity, such as blood pressure and weight," Small said.
The new results, he added, "reaffirm what many of us have been suspecting -- that what is good for your heart is going to be good for your brain. And we all have more control than we think over aging."
More information
To learn more about making physical activity a part of your life, visit the U.S. Centers for Disease Control and Prevention.
