A prospective study of physical activity and cognitive decline in elderly women - Women who walk

Background: Several studies have suggested that physical activity is positi vely associated with cognitive function in elderly persons. Evidence about this association has been limited by the cross-sectional design of most stu dies and by the frequent lack of adjustment for potential confounding varia bles. We determined whether physical activity is associated with cognitive decline in a prospective study of older women. Methods: We studied 5925 predominantly white community-dwelling women (aged greater than or equal to 65 years) who were recruited at 4 clinical center s and were without baseline cognitive impairment or physical limitations. W e measured cognitive performance using a modified Mini-Mental State Examina tion at baseline and 6 to 8 years later. Physical activity was measured by self-reported blocks (1 block approximate to 160 m) walked per week and by total kilocalories (energy) expended per week in recreation, blocks walked, and stairs climbed. Cognitive decline was defined as a 3-point decline or greater on repeated modified Mini-Mental State Examination. Results: Women with a greater physical activity level at baseline were less likely to experience cognitive de dine during the 6 to 8 years of follow-u p: cognitive decline occurred in 17%, 18%, 22%, and 24% of those in the hig hest, third, second, and lowest quartile of blocks walked per week (P < .00 1 for trend). Almost identical results were obtained by quartile of total k ilocalories expended per week. After adjustment for age, educational level, comorbid conditions, smoking status, estrogen use, and functional limitati on, women in the highest quartile remained less likely than women in the lo west quartile to develop cognitive decline (for blocks walked: odds ratio, 0.66 [95% confidence interval, 0.54-0.82]; for total kilocalories: odds rat io, 0.74 [95% confidence interval, 0.60-0.90]). Conclusions: Women with higher levels of baseline physical activity were le ss likely to develop cognitive decline. This association was not explained by differences in baseline function or health status. This finding supports the hypothesis that physical activity prevents cognitive decline in older community-dwelling women.