Physical Activity Predicts Population-Level Age-Related Differences in Frontal White Matter

Area of Science:

• Neuroscience
• Gerontology
• Radiology

Background:

• Physical activity benefits brain health across the lifespan.
• Few studies link physical activity to white matter microstructure and psychomotor speed in population samples.

Purpose of the Study:

• To investigate the mediating role of physical activity in age-related changes in white matter integrity and psychomotor speed.
• To examine associations between physical activity, white matter microstructure, and reaction time in a population-derived sample.

Main Methods:

• Diffusion tensor imaging (DTI) to assess white matter integrity (fractional anisotropy).
• A simple reaction time task to measure psychomotor speed.
• Analysis of a population-derived sample (N=399, ages 18-87) from the Cambridge Centre for Ageing and Neuroscience (Cam-CAN).

Main Results:

• Physical activity mediates the effect of age on white matter integrity.
• Higher physical activity is linked to better white matter preservation in frontal tracts (e.g., genu of corpus callosum, uncinate fasciculus).
• White matter integrity in the genu mediates age-related slowing of psychomotor speed.

Conclusions:

• A physically active lifestyle may protect against age-related structural brain disconnection.
• Physical activity may mitigate age-related declines in psychomotor speed by preserving white matter integrity.
• Findings highlight the importance of physical activity for maintaining brain health and cognitive function in aging.