The Role of Self-Reported Physical Sport Activity in Brain and Cognitive Aging

Abstract

Extensive research has evaluated how different lifestyle factors influence healthy aging, with recent studies focusing on brain health, as measured by white matter (WM) integrity and white matter hyperintensity (WMH) volume by magnetic resonance imaging (MRI), and cognitive performance. Physical activity (PA) among healthy older adults has been related to enhanced brain structure and cognition. Disruptions to cerebral WM, including decreased integrity and increased lesion load, may diminish connectivity within and between brain regions which may in turn negatively influence cognitive functioning, especially performance on tasks of executive function, memory, and processing speed. Therefore, I sought to further investigate the interactive effects between age and self-reported physical sports activity (PSA) on cognitive functioning and brain health, as measured by WM integrity and WMH volume, in a sample of 196 community-dwelling healthy older adults 50 to 89 years of age. First, I evaluated the interactive effects between age and PSA on WMH volume defined by both total and regional (i.e., frontal, temporal, parietal, and occipital) measures of lesion load. I identified significant main effects for age and age by PSA group interactions for total, frontal, temporal, and parietal WMH volumes. Second, I assessed the interactive effects between age and PSA on cognitive performance defined by measures of executive function, memory, and processing speed as such cognitive processes are known to be especially vulnerable to the effects of aging. I found significant main effects for age-group among all three cognitive domains and significant age by PSA interactions for measures of executive function, but not memory or processing speed. Third, I investigated the interactive effects between age and PSA on WMH-related integrity defined by fractional anisotropy (FA), mean diffusivity (MD; the molecular diffusion rate), radial diffusivity (RD; rate of diffusion perpendicular to WM fibers), and axial diffusivity (AD; rate of diffusion parallel to WM fibers). In order to account for both microstructural (i.e., WM integrity) and macrostructural (i.e., total WMH volume) measures of brain health, I used a model of multivariate regional covariance, the Scaled Subprofile Model (SSM), to create WMH-related integrity patterns for each diffusivity measure (i.e., FA, MD, RD, and AD) among 18 major WM tracts. For WMH-related FA, I observed overall age-related differences, but not interactive effects of age and PSA. For three diffusivity measures (i.e., WMH-related MD, RD, and AD), I observed main effects of age for RD and AD and significant interactive effects of age and PSA for all three measures. Together, the results of these analyses demonstrate how high levels of self-reported PSA moderates the association between healthy aging and brain and cognitive health. These findings help to identify a low cost and relatively low risk lifestyle factor that has the potential to help maintain brain health and cognition in the context of healthy aging.