Association of leisure-time physical activity with cognition by apolipoprotein-E genotype in persons aged 60 years and over: the National Health and Nutrition Examination Survey (NHANES-III)

OBJECTIVE: To test the hypothesis that aerobic-related leisure-time physical activity (PA) is associated with better cognitive function and that the effect varies among apolipoprotein E (APOE) genotype groups. DESIGN: Cross-sectional study of persons examined in the Third National Health and Nutrition Examination Survey (NHANES-III; 1988-1994). SETTING: US noninstitutionalized population. PARTICIPANTS AND METHODS: From a sample of 7159, aged ≥60 years, we analyzed data for 1799 older American men and women who had information on PA, a short mental status examination (SMSE), and were genotyped at the apolipoprotein E gene locus. RESULTS: In the initial bivariate analysis, non-ɛ4 carriers and ɛ4-heterozygotes performed better than ɛ4-homozygotes in the 60-69 age group. After controlling for multiple confounders including mobility limitation, PA correlated with a higher SMSE score in non-ɛ4 carriers (P = 0.014), but not in ɛ4 carriers (P = 0.887). At ≥70 years, PA also correlated with higher adjusted SMSE scores in non-ɛ4 carriers (P = 0.02); but this association became nonsignificant after controlling for mobility limitation (P = 0.12). CONCLUSION: In a nationally representative sample, PA was associated with enhanced cognition, an effect that was differentially influenced by apolipoprotein E genotype. Experimental studies are needed to determine whether or not PA can attenuate cognitive decline.