Physical activity, cognitive activity, and cognitive decline in a biracial community population

Background: Findings from studies investigating whether physical activity reduces the risk of cognitive decline in old-age have been inconsistent. Objective: To examine whether participation in physical activity by older adults reduces the rate of cognitive decline after accounting for participation in cognitively stimulating activities. Design: A prospective population study conducted from August 1993 to January 2003, with an average follow-up of 6.4 years. Setting: A biracial community population on the south side of Chicago. Participants: Participants were 4055 community-dwelling adults 65 years and older who were able to walk across a small room and had participated in at least 2 of the 3 follow-up assessments. Main Outcome Measure: Annual rate of cognitive change as measured by-a global cognitive score, which consisted of averaged standardized scores from 4 cognitive tests. Results: In a mixed model adjusted for age, sex, race, and education, each additional physical activity hour per week was associated with a slower rate of cognitive decline by 0.0007 U/y (P = .04). However, with further adjt stments (1) for participation in cognitive activities (P =. 0006, P = .10), (2) for depression and vascular diseases ((beta) over cap = .0005, P = .19), and (3) by excluding participants whose global cognitive score at baseline was at or below the 10th percentile ((beta) over cap = .0002, P = .45), the coefficients were smaller and no longer statistically significant. Conclusion: These data do not support the hypothesis that physical activity alone protects against cognitive decline among older adults.