Exercise helps ward off dementia in older adults

NEW YORK (Reuters Health) - Older adults who exercise regularly are less likely to develop dementia than their sedentary peers, new research shows.

The report suggests that adults "who walk just three times a week for 15 minutes each will cut their risk of dementia -- but in my practice, I counsel patients to make exercise an everyday habit," lead author Dr. Eric B. Larson, from the Group Health Cooperative in Seattle, told Reuters Health.

Dr. Larson said that his team's study is "larger and more robust" than previous studies looking at this topic and measures were taken to reduce the chances that a subject might have early dementia at the start of the study. Still, he said that the risk reduction seen with regular exercise in this study -- 38 percent -- is "in the ballpark" of the estimates reached by other studies.

The study, which is reported in the Annals of Internal Medicine, involved 1740 subjects who were at least 65 years of age at enrollment. The subjects had no evidence of cognitive impairment at the outset and scored above the 25th percentile on a standard cognitive function screening test. The participants were evaluated every 2 years to determine the incidence of dementia.

During average follow-up period of 6 years, 158 subjects developed dementia, including 107 with Alzheimer's disease.

The rate of dementia among adults who exercised at least three times per week was the equivalent of 13.0 cases per 1000 persons per year, significantly lower than the rate seen among less active adults - 19.7 per 1000 person-years.

Dr. Larson said that while regular exercise may not prevent dementia altogether, it could spare many older adults from "having the late life experience of being badly demented."

In a related editorial, Dr. Laura J. Podewils, from the Centers for Disease Control and Prevention in Atlanta, and Dr. Eliseo Guallar, from Johns Hopkins Bloomberg School of Public Health in Baltimore, comment that further research is needed to define the "type, frequency, intensity, or duration of physical activity that is most beneficial in preventing cognitive deterioration."

SOURCE: Annals of Internal Medicine, January 17, 2006.