Physical Activity Level Moderates the Association Between Response Inhibition and Anterior Cingulate Cortex Volume in Older Adults

Abstract

AbstractBackgroundAging is generally associated with a decline in executive function, a cognitive domain that is critical to functional independence. Response inhibition is an executive process that contributes to anticipation, planning, and goal setting. The anterior cingulate cortex (ACC) is a key brain structure that supports response inhibition and shows gray matter loss with age. Evidence suggests that both response inhibition performance and the Anterior Cingulate Cortex (ACC) are responsive to exercise training. Whether physical activity moderates the relationship between response inhibition and the ACC in older adults is unknown.MethodA cross‐sectional analysis of a subset of community‐dwelling older adults enrolled in a 3‐arm, 8‐week proof of concept randomized control trial of computerized cognitive training, with or without exercise, who completed T1 magnetic resonance imaging (MRI) at baseline. Of the 68 MRI participants, 11 were removed from this analysis due to poor scan quality. Response inhibition was measured using the Flanker Task from the NIH Toolbox Cognitive Battery. Participants were split into either a high or low physical activity groups determined by their median Physical Activity Scale for the Elderly (PASE) score. Caudal and rostral ACC volumes were segmented and quantified using FreeSurfer. To assess for moderation, we performed linear regressions with age‐adjusted Flanker Task score as the dependent variable, and ACC volume, high/low PASE, and the interaction of ACC volume * high/low PASE as independent variables.ResultPhysical activity level significantly moderated the association between left caudal anterior cingulate cortex (LCACC) volume and age‐adjusted Flanker Task score, (β = –6.428, t(53) = ‐2.075, p < .05). Among those with low physical activity levels (n = 30), greater LCACC volume was associated with better response inhibition (r = 0.44, p = .01) while there was no association among those with high physical activity levels (n = 27; r = ‐0.13; p = .52).ConclusionHigher physical activity may mitigate the negative effects of age‐related gray matter loss in the ACC on response inhibition performance in community‐dwelling older adults.