Physical Activity and Amyloid-β Brain Levels in Elderly Adults with Intact Cognition and Mild Cognitive Impairment

Abstract

Objectives: To examine the associations between amyloid-β brain deposition and physical activity (PA) in elderly adults without dementia and to investigate whether the association has a dose-response relationship.

Design: Cross-sectional study.

Setting: French community-dwelling people.

Participants: Elderly adults with normal or mildly impaired cognition (mean age 74.7 ± 4.2; 60.4% female) with available information on current self-reported PA and amyloid-β brain deposition measured using positron emission tomography (PET) using the PET-ligand florbetapir F 18 (n = 268).

Measurements: A standardized uptake value ratio (SUVR) was obtained for each subject. Participants were divided according to amyloid plaque cortical retention defined according to a SUVR cutoff of 1.10 (SUVR+ vs SUVR-).

Results: Bivariate and multivariate analyses showed that PA was not significantly associated with SUVR. SUVR+ and SUVR- participants did not differ in terms of volume (continuous PA variables) and levels (categorical PA variables) of PA. PA was not correlated with SUVR in apolipoprotein E ε4 carriers or noncarriers. PA was not associated with cognitive function.

Conclusion: Although PA protects against dementia, there is no solid evidence that this protection involves a reduction in amyloid-β brain deposition. Further studies are needed to determine whether PA (ideally measured at several time-points using objective measures) is involved in the pathophysiology of Alzheimer's disease.

Keywords: Alzheimer's disease; amyloid plaques; elderly; older adults; physical activity.