Associations between sedentary time with cognitive activity and brain volume among vulnerable older adults

Abstract

Abstract Background: Vulnerable older adults tend to decrease physical activity and increase sedentary time. Previous research on the associations between sedentary time and brain volume produced inconsistent findings, without considering the impact of cognitive activity on cognitive function. We aimed to examine the association between sedentary time with cognitive activity or non-cognitive activity, and brain volume. Methods: A structural magnetic resonance imaging survey was conducted among community‐dwelling vulnerable older adults. Brain volumetric measurements were obtained using 3T magnetic resonance imaging and pre‐processed using FreeSurfer. Sedentary time with or without cognitive activity was assessed using a 12‐item questionnaire. Physical activity was assessed by the frequency of light and moderate levels of physical exercise according to the Japanese version of the Cardiovascular Health Study criteria. Participants were categorized into a low activity group and moderate‐to‐high activity group. Results: Among 91 participants (83.1 ± 5.2 years old, 61.5% female), 26 were low active. The overall sample and moderate‐to‐high activity group did not show significant positive effects on brain volume for sedentary time with cognitive activity. In the low activity group, isotemporal substitution models showed that reallocation from sedentary time with non‐cognitive activity to cognitive activity was significantly associated with increased brain volumes in some areas, including the rostral and caudal anterior cingulate (β = 0.486–0.618, all P < 0.05, Adjusted R2 = 0.344–0.663). Conclusions: Our findings suggest that reallocation from sedentary time with non‐cognitive activity to cognitive activity is protectively associated with brain volume in vulnerable older adults with low activity.