Physical activity predicts gray matter volume in late adulthood

TLDR

Physical activity has been hypothesized to preserve gray matter volume in late adulthood, yet longitudinal evidence has been lacking. This study examined whether weekly walking predicts greater gray matter volume after nine years, identified a walking threshold for volume preservation, and assessed whether such volume reduction lowers cognitive impairment risk 13 years later in 299 adults. Participants (mean age 78) reported weekly walking blocks, underwent high‑resolution brain scans nine years later, and were followed for cognitive impairment adjudication 13 years after baseline, with baseline covariates including white matter hyperintensities and ventricular grade. Greater walking was associated with larger frontal, occipital, entorhinal, and hippocampal volumes; 72 blocks per week was the threshold for volume increase, and higher gray matter volume linked to walking reduced cognitive impairment risk by two‑fold.

Abstract

Physical activity (PA) has been hypothesized to spare gray matter volume in late adulthood, but longitudinal data testing an association has been lacking. Here we tested whether PA would be associated with greater gray matter volume after a 9-year follow-up, a threshold could be identified for the amount of walking necessary to spare gray matter volume, and greater gray matter volume associated with PA would be associated with a reduced risk for cognitive impairment 13 years after the PA evaluation.In 299 adults (mean age 78 years) from the Cardiovascular Health Cognition Study, we examined the association between gray matter volume, PA, and cognitive impairment. Physical activity was quantified as the number of blocks walked over 1 week. High-resolution brain scans were acquired 9 years after the PA assessment on cognitively normal adults. White matter hyperintensities, ventricular grade, and other health variables at baseline were used as covariates. Clinical adjudication for cognitive impairment occurred 13 years after baseline.Walking amounts ranged from 0 to 300 blocks (mean 56.3; SD 69.7). Greater PA predicted greater volumes of frontal, occipital, entorhinal, and hippocampal regions 9 years later. Walking 72 blocks was necessary to detect increased gray matter volume but walking more than 72 blocks did not spare additional volume. Greater gray matter volume with PA reduced the risk for cognitive impairment 2-fold.Greater amounts of walking are associated with greater gray matter volume, which is in turn associated with a reduced risk of cognitive impairment.