Motivation: Explore the spatiotemporal associations between aging of the white matter (WM) and gray matter (GM). Goal(s): Study aimed to examine the effects of WM microstructure properties on 4-year change in GM cortical morphology. Approach: Cortical thickness, volume and surface area were obtained from T1w images. ROIs were delineated using Von Economo atlas. Diffusion metrics were generated from an ROI in the WM subtended directly below the GM ROIs. Diffusion metrics and age were entered as predictors in regression models with change in GM as dependent variable. Results: Coupled GM-WM aging was found in several association regions indicating that WM and GM age together. Impact: Longitudinal methods can tease apart lead-lag associations between aging of GM and WM. These neuronal parts have different biological make-up and they differ in susceptibility to age-related damage.
Kennedy et al. (Tue,) studied this question.