Accelerometer‐measured physical activity timing with incident dementia

Abstract INTRODUCTION Moderate to vigorous physical activity (MVPA) is linked to lower dementia risk, though the optimal timing remains unclear. METHODS Using accelerometer‐measured MVPA data from 90,329 dementia‐free UK Biobank participants with at least 2 years of follow‐up, we assessed associations between MVPA patterns (morning, afternoon, evening, mixed, inactive) and dementia risk via multivariable‐adjusted Cox proportional hazards models. RESULTS Compared to the inactive group, participants with a tendency of morning MVPA had a lower risk of all‐cause dementia (hazard ratio [HR]: 0.60, 95% confidence interval [CI]: 0.40–0.90) and Alzheimer's disease (AD) risk (HR: 0.44, 95% CI: 0.22–0.86). No association of the other time point with all‐cause dementia was observed. Additionally, the incidence of vascular dementia (VD) did not exhibit a significant relationship among all timing groups. DISCUSSION Morning MVPA was associated with a lower risk of all‐cause dementia and AD, while MVPA at any time point showed no association with VD. Highlights Few studies have examined accelerometer‐measured moderate to vigorous physical activity (MVPA) timing with incident dementia. Participants with a tendency of morning MVPA had a lower risk of all‐cause dementia and Alzheimer's disease. No significant association was found between all MVPA timing and vascular dementia (VD) risk. Findings suggest timing‐specific physical activity interventions for dementia prevention.