Total daily physical activity and the risk of AD and cognitive decline in older adults

TLDR

Studies have not yet examined the link between objective total daily physical activity and incident Alzheimer disease. The study tested whether objective total daily physical activity predicts incident AD and cognitive decline. Continuous actigraphy measured total daily activity over 10 days in 716 older adults, who were then followed annually with a 19‑test cognitive battery. Higher total daily physical activity was associated with a 52% lower risk of incident AD (HR = 0.48) and slower global cognitive decline over ~4 years, independent of demographics, health, and APOE status.

Abstract

<h3>Objective:</h3> Studies examining the link between objective measures of total daily physical activity and incident Alzheimer disease (AD) are lacking. We tested the hypothesis that an objective measure of total daily physical activity predicts incident AD and cognitive decline. <h3>Methods:</h3> Total daily exercise and nonexercise physical activity was measured continuously for up to 10 days with actigraphy (Actical®; Philips Healthcare, Bend, OR) from 716 older individuals without dementia participating in the Rush Memory and Aging Project, a prospective, observational cohort study. All participants underwent structured annual clinical examination including a battery of 19 cognitive tests. <h3>Results:</h3> During an average follow-up of about 4 years, 71 subjects developed clinical AD. In a Cox proportional hazards model adjusting for age, sex, and education, total daily physical activity was associated with incident AD (hazard ratio = 0.477; 95% confidence interval 0.273–0.832). The association remained after adjusting for self-report physical, social, and cognitive activities, as well as current level of motor function, depressive symptoms, chronic health conditions, and <i>APOE</i> allele status. In a linear mixed-effect model, the level of total daily physical activity was associated with the rate of global cognitive decline (estimate 0.033, SE 0.012, <i>p</i> = 0.007). <h3>Conclusions:</h3> A higher level of total daily physical activity is associated with a reduced risk of AD.