CURRENT AND PAST PHYSICAL ACTIVITY AND RISK OF ALZHEIMER’S DISEASE IN OLDER ADULTS

Abstract

Previous findings have suggested a protective role of physical activity (PA) on Alzheimer's disease (AD) risk, but few studies have examined both past and current PA. The current study included 1288 participants of Washington/Hamilton Heights-Inwood Columbia Aging Project, a community-based, multiethnic, elderly population in New York City. The metabolic equivalent (MET) was calculated for self-reported current PA and past PA [average PA in early life (12-25 years), early-middle life (26-50 years), and late-middle life (>50 years)] using standard questionnaires administered at baseline. Cox regression models were used to estimate hazards ratios (HRs) for AD, adjusted for age, sex, race/ethnicity, education, and apolipoprotein E (APOE) genotype. A total of 104 incident AD dementia cases were identified among 5,321 person-years in 1288 initially non-demented participants during follow-up (on average 4.14 years). Higher current PA was associated with lower risk of AD: compared to those with the lowest tertile of PA, those with the highest PA had a lower risk of developing AD (HR=0.46, 95%CI=0.24−0.87, p=0.02; p-trend=0.01), even after additional adjustment for BMI, occupation, and medical comorbidities (p-trend=0.03). Similarly, comparing the highest tertile to the lowest tertile of mean past PA, the HR was 0.36 (95%CI=0.18−0.76, p=0.007; p-trend=0.02). Results remained similar when considering current and historical PA simultaneously in the model, with a 47% and 59% reduction in AD risk, respectively. PA at age 12–25 (p-trend=0.04) and at age 50 and above (p-trend <0.0001) were associated with reduced risk of AD. Comparing with “always low PA”, “increased to high PA” (HR=0.47, p=0.05) and “decreased from high PA” (HR=0.31, p=0.01) both had a reduced risk of AD. Comparing with “never high PA”, “ever high PA” had a 59% (p=0.001) reduction in risk of AD. Current and past light-intensity PA were both associated with reduced risk of AD, with HR=0.50 (95%CI=0.28−0.91, p=0.024) and 0.46 (95%CI=0.23−0.93, p=0.03) comparing the highest with the lowest light-intensity METs tertiles, respectively. These findings suggest that physical activity throughout life is associated with lower risk of AD. Both young and old individuals can reduce their likelihood of developing AD via physical activity, including frequent light-intensity activities.