The association between doubly labeled water- and accelerometer-measured physical activity, brain volume, and cognitive function in older adults with cardiometabolic or functional risks.

Regular physical activity is beneficial for brain health. However, no research has explored whether physical activity level (PAL) assessed by the doubly labeled water method (PAL-DLW) is associated with brain volume and cognitive function. We investigated whether PAL-DLW, accelerometer-assessed PAL (PAL-Acc), and components of physical activity are associated with brain volume and cognitive function in older adults. We analyzed data from 49 participants with cardiometabolic or functional risks (35 female participants, age: 71.1 ± 6.9 years). PAL-DLW was calculated from total energy expenditure and estimated basal metabolic rate. PAL-Acc and components of physical activity were calculated using triaxial accelerometer data. Brain volumes were measured using T1-weighted magnetic resonance imaging. Cognitive function was assessed using the Trail Making Test and Logical Memory. Data were classified into tertiles and analyzed using an analysis of covariance and a linear trend analysis. We found no significant associations of PAL-DLW with brain volumes or cognitive function. The frontal cortex volume was associated with PAL-Acc (main effect: p = 0.006, trend: p = 0.035) and low-intensity physical activity (LPA) time (main effect: p = 0.015, trend: p = 0.009). Specifically, the dorsolateral prefrontal cortex volume was associated with PAL-Acc (main effect: p = 0.002, trend: p = 0.017) and LPA time (main effect: p = 0.005, trend: p = 0.005). Conversely, the precentral gyrus volume exhibited no associations. Our findings highlight the potential role of physical activity in mitigating volume reduction in higher-order brain regions in older adults with risk factors.