Association of physical activity with incident dementia and cognitive decline among Australian older adults

We investigated the association between physical activity (PA) intensity and dementia and cognitive decline in Australian community-dwelling older adults. This prospective cohort study uses data from 11,655 older adults (mean age (standard deviation, SD) = 75.0 (4.2) years, 53.4% females, 52.9% had completed ≥ 12 years of education), who were participants in the ASPirin in Reducing Events in the Elderly (ASPREE) clinical trial and its observational follow-on (ASPREE-XT) and the ASPREE Longitudinal Study of Older Persons (ALSOP) sub-study. Participants self-reported the exposure of usual PA intensity (never/rarely, light, moderate, vigorous). Dementia was adjudicated using the Diagnostic Manual of Mental Disorders 4th Edition and supporting evidence; cognitive decline was defined as a > 1.5 standard deviation reduction from baseline on any cognitive assessment. Associations were explored using hazard ratios from Cox regression models with adjustment for demographic, socio-economic, behavioural and clinical factors. Of 11,655 participants (mean age 75.0 years) over a median 10.4-year follow-up, 931 (8.0%) developed dementia and 3552 (30.8%) cognitive decline. Compared with light PA, dementia or cognitive decline risk was 79% (95% CI 1.14-2.83) and 58% (95% CI 1.21-2.05) higher, respectively, among those who rarely/never engaged in PA, but no further decreases occurred with higher levels of PA. Engagement in light PA may help lower dementia and cognitive decline risk in older adults.