Spatial navigation, physical activity, and Alzheimer disease biomarkers

Abstract

AbstractBackgroundElevated levels of amyloid are associated with worse performance on cognitive mapping (CM), a spatial navigation task reliant on the hippocampus. Prior animal work found that exercise is associated with better learning in CM tasks. Hence, the first goal of the study was to examine whether physical activity moderates the relationship between amyloid deposition and CM. In addition, spatial navigation ability predicts Alzheimer disease (AD) clinical progression but there is a need to examine whether it also predicts subsequent levels of amyloid and tau. Hence, the second goal was to examine whether CM predicts later levels of PET‐Tau and longitudinal trajectories of PET‐Amyloid.MethodCognitively normal individuals (n = 65; age range 50‐84 years) were administered a CM task in a virtual environment and a self‐report measure of physical activity. For cross‐sectional analyses, amyloid deposition was estimated via cerebrospinal fluid levels of Aβ42. One assessment of PET‐Tau (n = 49) and repeated assessments of PET‐Amyloid (n = 59) were obtained following the CM session.ResultConcurrent amyloid deposition was associated with reduced learning (p = 0.002) and retention of the environment (p = 0.002) while greater physical activity was associated with better learning (p = 0.004). There was no moderation by physical activity (all p’s > 0.156). CM performance was not associated with longitudinal trajectories of PET‐Amyloid (all p’s > 0.330) or the subsequent levels of PET‐Tau (all p’s > 0.572).ConclusionThese results suggest that both current physical activity and levels of amyloid can be important predictors of spatial navigation skills. However, CM might be a limited predictor of AD biomarker accumulation. Future studies should use a larger sample size and greater number of assessments to examine these questions.