July 13, 2009 (Vienna, Austria) -- When it comes to honing your mental skills, it's never too late to start exercising.
In a new study, sedentary older people who began new exercise programs curbed their rate of cognitive decline, especially when it came to the ability to process complex information quickly.
"Even if you've stopped exercising, get back on the horse," says researcher Deborah E. Barnes, PhD, MPH, of the University of California, San Francisco, tells WebMD. "The worst thing is to stay sedentary."
Other studies have shown that older adults who are physically active experience a slower decline in mental skills ranging from recall to reasoning than their sedentary counterparts.
But most people, especially older adults, don't follow a consistent exercise pattern over time, Barnes says. "They may get sick, or have work commitments, and stop exercising."
To determine the impact of changes in the level of physical activity on the rate of cognitive decline, Barnes and colleagues followed more than 3,000 people, ages 70 to 79, for seven years. Of the total, 21% of participants were consistently sedentary, 12% maintained their activity levels, 26% had declining levels, and 41% had increasing or fluctuating activity levels.
The researchers found that people who were consistently sedentary had the worst mental skills. On a standard test that measures overall cognitive function, including memory, attention span and problem-solving, "they scored the worst at the beginning and experienced the fastest rate of cognitive decline," Barnes says.
Not surprisingly, people whose exercise levels consistently dropped over the seven-year period didn't fare that well either, she says. Their rate of cognitive decline was faster than that of people who had stable, increasing, or fluctuating activity levels.
"Sedentary individuals should engage in physical activity at least occasionally," Barnes says. "People who are active should maintain or increase their activity levels."
The findings were presented at the Alzheimer's Association 2009 International Conference on Alzheimer's Disease.
Exercise Improves Prognosis of Alzheimer's Patients
A second study showed that exercise may help to extend the lives of people with Alzheimer's disease.
Studies have shown that physical activity may protect against the development of Alzheimer's disease, says Nikolaos Scarmeas, MD, of Columbia University in New York.
"But what about after you get Alzheimer's disease? Does it affect the prognosis?" he asks.
To find out, Scarmeas and colleagues followed more than 500 people with Alzheimer's disease for three to four years.
Compared with Alzheimer's patients who did not exercise at all, those who were physically active were 44% to 59% less likely to die during the study period.
"Even a small amount of physical activity -- 30 minutes of moderate exercise, like biking, a week -- was associated with a lower risk of dying," Scarmeas tells WebMD.
Ronald Petersen, MD, PhD, professor of neurology at the Mayo Clinic in Rochester, Minn., and chairman of the Alzheimer's Association Medical & Scientific Advisory Council, says that both studies confirm the overwhelming benefits of exercise on the brain.
"We recommend that elderly people and those with Alzheimer's disease remain physically and mentally active," Petersen tells WebMD. "It's a small investment for a potentially big gain.