Physical activity domains and cognitive function over three years in older adults with subjective memory complaints: Secondary analysis from the MAPT trial

Objectives: We aimed to examine the associations of physical activity (PA) domains (i.e., PA in leisure time (LTPA), for housework (HPA), or for gardening (GPA)) with cognitive function in older adults with subjective memory complaints (no-dementia) and to investigate if those associations were dependent on the status of apolipoprotein E allele 4 (APOE4), omega-3 levels and mild cognitive impairment (MCI). Design: Observational prospective secondary analysis using longitudinal data from a randomized controlled trial. Methods: Participants were 420 French community-dwelling people (aged 75.6 +/- 4.4; 66.4% women) randomized into the placebo group. They were assessed at baseline, 6-, 12-, 24- and 36-month using a battery of neuropsychological tests; a composite cognitive Z score was elaborated for all time points. Data on PA come from baseline and was obtained using a self-reported questionnaire. Results: In time-adjusted analysis, LTPA significantly predicted cognitive function over three years for almost all tests and the composite Z score, with higher LTPA associated with better function; multivariate analysis showed a significant association only for verbal fluency. HPA was not associated to cognitive function, whereas GPA had mixed results. The magnitude of the PA-cognition associations was very weak, being the strongest for LTPA. Stratified analyses showed that the associations between PA and cognitive function were stronger for MCI, people with normal omega-3 index levels, and APOE4 non-carriers. Conclusions: PA domain is an important aspect to take into account when examining the associations between PA and cognitive function. Biomarkers of cognitive function may modulate the PA-cognition associations. (C) 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.