The effect of midlife physical activity on cognitive function among older adults: AGES - Reykjavik study

Background. There are few studies on the long-term associations of physical activity (PA) to cognition. Here, we examine the association of midlife PA to late-life cognitive function and dementia. Methods. The sample consisted of a population-based cohort of men and women (born in 1907-1935) participating in the Age Gene/Environment Susceptibility - Reykjavik Study. The interval between the midlife ascertainment of PA and late-life cognitive function was 26 years. Composite scores of speed of processing, memory, and executive function were assessed with a battery of neuropsychological tests, and dementia was diagnosed according to international guidelines. There were 4,761 nondemented participants and 184 (3.7%) with a diagnosis of dementia, with complete data for the analysis. Results. Among the participants, no midlife PA was reported by 68.8%, ≤5 hours PA by 26.5%, and >5 hours PA by 4.5%. Excluding participants with dementia compared with the no PA group, both PA groups had significantly faster speed of processing (≤5 hours, β =. 22; >5 hours, β =. 32, p trend <. 0001), better memory (≤5 hours, β =.15; >5 hours, β =. 18, p trend <. 0001), and executive function (≤5 hours, β =. 09; >5 hours, β =. 18, p trend<. 0001), after controlling for demographic and cardiovascular factors. The ≤5 hours PA group was significantly less likely to have dementia in late life (odds ratio: 0.6, 95% confidence interval: 0.40-0.88) after adjusting for confounders. Conclusion. Midlife PA may contribute to maintenance of cognitive function and may reduce or delay the risk of late-life dementia.