Year: 2012
Type: article
Study design: Observational Study
Abstract: Aging is marked by a decline in cognitive function, which is often preceded by losses in gray matter volume. Fortunately, higher cardiovascular fitness (CVF) levels are associated with an attenuation of age-related losses in gray matter volume and a reduced risk for cognitive impairment. Despite these links, we have only a basic understanding of whether fitness-related increases in gray matter volume lead to elevated cognitive function. In this cross-sectional study, we examined whether the association between higher aerobic fitness levels and elevated executive function was mediated by greater gray matter volume in the prefrontal cortex (PFC). One hundred and forty-two older adults (mean age = 66.6 years) completed three classic executive function tasks yielding five measures of ability: incongruent trial reaction time (RT) and percent interference from the Stroop task, number of perseverative errors in the Wisconsin Card Sorting Task (WCST), and forward and backwards digit span length. In addition, participants completed structural magnetic resonance imaging (MRI) scans and CVF assessments. Gray matter volume in the PFC was assessed using an optimized voxel-based morphometry approach. Consistent with our predictions, higher fitness levels were associated with (a) better performance on both the Stroop and WCST tasks, and (b) greater gray matter volume in several regions, including the dorsolateral PFC (DLPFC). Bilateral volume of the inferior frontal gyrus and precentral gyrus mediated the relationship between CVF and Stroop performance while a non-overlapping region in the left middle frontal gyrus mediated the association between CVF and WCST perseverative errors. Control analyses using a non-prefrontal brain region (right occipital lobe) as a mediator and a task not heavily reliant upon executive function (vocabulary) yielded null results in mediation analyses. This dissociation of brain areas suggests that higher fitness levels are associated with better executive function by means of greater gray matter volume in specific areas of the PFC.
Author: Andrea M. Weinstein
Language: English
Topic: Physical Activity and Health
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W567120864