Aim: To investigate the influence of replacing sedentary time with physical activity on cognitive function using an isotemporal substitution model in a population of community-dwelling oldest old. Methods: This cross-sectional study included residents of the Arakawa ward, Tokyo, who were part of a prospective cohort from the Arakawa 85+ study. We measured physical activity in 136 participants using a triaxial actigraph. Cognitive function was measured using the Addenbrooke's Cognitive Examination-III and participants were divided into a “cognitive decline group” (Addenbrooke's Cognitive Examination-III ≤88) and “cognitive maintain group” (Addenbrooke's Cognitive Examination-III ≥89). Physical activity was divided into three categories: sedentary behavior (≤1.5 metabolic equivalents), light physical activity (>1.5 to <3.0 metabolic equivalents), and moderate-to-vigorous physical activity (≥3 metabolic equivalents). Using an isotemporal substitution approach, we applied multiple logistic regression analysis to demonstrate the association between cognitive function and replacing 30 min/day of sedentary behavior with an equal period of light physical activity. Covariates included age, education and the Center for Epidemiologic Studies Depression Scale. Results: Our findings showed that in men, replacing 30 min of sedentary behavior per day with light physical activity was associated with a 1.47-fold increase in the odds of maintaining cognitive function. An association between physical activity and cognitive function was not observed in female participants. Conclusions: Our results indicate that substituting sedentary behavior with light physical activity could be helpful in maintaining cognitive function in community-dwelling oldest old men. These results highlight the importance of behavioral changes to promote cognition. Geriatr Gerontol Int 2020; 20: 773–778.
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