Effects of Sedentary Behavior and Physical Activity on Cognitive Function are Conferred by Cortical Thickness

Abstract

Physical activity and aerobic fitness may have positive impacts on brain structure and function in older adults. Conversely, sedentary behavior may have negative effects. PURPOSE: To determine associations of sedentary behavior with cerebral cortical thickness and neurocognitive function in older adults in cognitively normal older adults (NC) and patients with mild cognitive impairment (MCI). METHODS: We tested 28 NC and 50 MCI participants matched for age, sex, and education. Participants wore a 3D accelerometer for 1 week to measure daily physical activity levels. Minutes spent in sedentary behavior (<4.0METs) and moderate-to-vigorous physical activity (MVPA) (>5.0METs) were recorded. RESULTS: Sedentary behavior and MVPA were associated with cortical thickness in multiple brain regions within the default mode network. The effects of sedentary behavior on Trails B performance were mediated through left middle temporal gyrus (B=0.0017, SE=0.0010, 0.0002 to 0.0046 95% CI) and right frontal pole (B=0.0027, SE=0.0013, 0.0006 to 0.0058 95%CI) cortical thickness. MVPA (B=-0.011, SE=0.0070, -0.0304 to -0.0006 95%CI) positively impacted Trails B through left middle temporal gyrus thickness. California Verbal Learning Test cued recall was negatively affected by sedentary behavior (B=-0.00026, SE=0.0013, 0.0006 to 0.0058 95%CI), but positively affected by MVPA (B=0.0012, SE=0.0008, 0.0001 to 0.0033 95%CI) through right superior parietal cortical thickness. Cognitive status moderated the association of sedentary behavior with left posterior cingulate thickness (interaction, p=0.02) and MVPA to right supramarginal gyrus thickness (interaction, p=0.04) with greater effects occurring in NC. CONCLUSION: Sedentary behavior is associated with reductions in cerebral cortical thickness which lead to impairment in memory and executive function in older adults. Sedentary behavior may be more detrimental to individuals with normal cognitive function. Supported by the NIH (R01AG033106)