The variety of leisure and physical activity one engages in -- and not its intensity in terms of calories expended - may reduce dementia risk in older people, according to researchers at Johns Hopkins.
An association between variety of activity and dementia risk, however, did not hold up in those with the so-called APOE-4 genetic predisposition to the disease found in about one-quarter to one-third of Alzheimer's patients, according to a report appearing in the April 1, 2005, issue of the American Journal of Epidemiology.
General physical activity is already known to enhance cardiovascular health and help maintain independence and quality of life in older people, but the results of this study - which establish a statistical association, and not a direct cause and effect, between variety of exercise and reduced dementia risk -- suggest that participating in a number of different activities may be as or more important than frequency, duration, and intensity of physical activity with respect to dementia risk, according to the report.
"We don't yet know why this association exists or what causes it.
It could well be that maintaining a variety of activities keeps more parts of the brain active, or that this variety reflects better engagement in both physical and social activities. Confirmation of this association in future studies may provide an additional impetus for people to remain or become engaged in several physical and other leisure activities later in life," says Constantine G. Lyketsos, M.D., professor of psychiatry and behavioral sciences at Johns Hopkins and senior author on the report.
The study included 3,375 men and women age 65 years or older who participated in the Cardiovascular Health Cognition Study from 1992 to 2000 and who did not have dementia at the onset of the study. Each study volunteer was asked to fill out a questionnaire about the frequency and duration of the 15 most common types of physical activity in older adults, including walking, household chores, mowing, raking, gardening, hiking, jogging, biking, exercise cycling, dancing, aerobics, bowling, golfing, general exercise and swimming. The researchers then created an activity index, calculated as the number of different activities each subject participated in over the previous two weeks.
Other measurements, including APOE gentotype, age, gender, education level, ethnicity, smoking, alcohol use, and other physical and mental health-related history, were also considered in the study.