Physical Performance and Amyloid-β in Humans : A Systematic Review and Meta-Analysis of Observational Studies

Background: Accumulation of amyloid-β (Aβ) plaques is one of the main features of Alzheimer’s disease (AD). Physical performance has been related to dementia risk and Aβ, and it has been hypothesized as one of the mechanisms leading to greater accumulation of Aβ. Yet, no evidence synthesis has been performed in humans. Objective: To investigate the association of physical performance with Aβ in humans, including Aβ accumulation on brain, and Aβ abnormalities measured in cerebrospinal fluid (CSF) and blood. Methods: A systematic review with multilevel meta-analysis was performed from inception to June 16th, 2022. Studies were eligible if they examined the association of physical performance with Aβ levels, including the measure of physical performance as a predictor and the measure of Aβ as an outcome in humans. Results: 7 articles including 2,619 participants were included in the meta-analysis. The results showed that physical performance was not associated with accumulation of Aβ in the brain (ES = 0.01; 95% CI –0.21 to 0.24; I2 = 69.9%), in the CSF (ES = –0.28; 95% CI –0.98 to 0.41; I2 = 91.0%) or in the blood (ES = –0.19; 95% CI –0.61 to 0.24; I2 = 99.75%). Significant heterogeneity was found across the results , which posed challenges in arriving at consistent conclusions; and the limited number of studies hindered the opportunity to conduct a moderation analysis. Conclusions: The association between physical performance and Aβ is inconclusive. This uncertainly arises from the limited number of studies, study design limitations, and heterogeneity of measurement approaches. More studies are needed to determine whether physical performance is related to Aβ levels in humans.