Association between middle- to late-life physical performance and incident Alzheimer's disease: Recent findings and potential mechanisms

Abstract

Dementia is recognized as one of the major formidable public health challenges in modern aging societies. Among the several subtypes of dementia, Alzheimer’s disease (AD) is the most frequent, probably accounting for 40-50% of total dementia cases. Recent findings from prospective cohort studies suggest that impairment, found in certain physical performance measures, precedes the clinical diagnosis of AD. The main aim of this review paper is to provide a brief summary of recent findings regarding the associations between middle- to late-life physical performance measures and incident AD and total dementia including AD. This paper also aims to discuss the potential mechanisms underlying the prospective associations between physical performance and incident AD. The reviewed findings suggest that poor baseline status in physical performance measures, including gait performance, muscle strength, balance, aerobic performance, and composite physical performance, is associated with greater risk for the subsequent incidence of AD. Preclinical pathologies leading to AD and physical fitness are named as part of plausible factors underlying the prospective association between physical performance and incident AD. It is also speculated that the prospective association is mostly non-causal, where physical performance measures probably serve as “early markers” of the future incidence of AD. Further studies are expected to establish solid evidence of the prospective association, to clarify the whole picture of the mechanisms underlying the association, and to explore the practical application of physical performance measures in attempts to identify individuals at a higher risk of AD before or early in the disease.