Physical activity promotes longitudinal white matter brain adaptations that support fluid intelligence with age

Abstract

The aging population continues to grow, and along with it the need to better understand the unique characteristics of the aging brain. Despite the cortical thinning and myelin degeneration that occurs in later life, many individuals are resilient to these changes and are relatively spared from cognitive decline (so called "super-agers"). Longitudinal magnetic resonance imaging data from the Human Connectome Project allowed us to probe the underlying white matter connections that are strengthened or pruned to support fluid intelligence in younger and older adults, while also investigating physical activity as a potential behavioural intervention to promote these network reorganizations. Multivariate partial least squares analysis and the recent method of correlational tractography identified parts of the white matter structural connectivity network, measured with diffusion magnetic resonance imaging, where strengthening or pruning were associated with positive fluid intelligence trajectories and promoted by physical activity. This research improves our understanding of how the brain network adapts in later life, identifies physical activity as an accessible intervention to promote this adaptation, and enriches our fundamental models of what the brains neural network is capable of.