Is the effect of reported physical activity on disability mediated by cognitive performance in white and african american older adults?

This study examined if reported physical activity has beneficial outcomes on disability through cognitive performance-mediated effects and if these mediation effects are comparable for White and African American elders. Longitudinal data from the Assets and Health Dynamics among the Oldest Old study (N = 4,472) are used to test mediation in multilevel models. During the 7-year follow-up, cognitive performance mediated the effects of reported physical activity on disability in the entire sample and in Whites but not in African Americans. Our results indicate that reported physical activity may delay the disability development through improvement in cognitive performance. Unmeasured education and comorbidity influences may have obscured the mediation effects in African Americans. Reported physical activity plays a key role in the independence of older adults and should be particularly promoted in African Americans and during the entire life course.