Free Water Collapse in Limbic White Matter Predicts Memory Decline in Aging and Alzheimer Disease
A large multisite analysis (n=4,467) finds white matter free water (FW), especially in limbic tracts (cingulum, fornix), strongly associates with cross-sectional cognition and longitudinal decline; FW interacts with amyloid, APOE ε4, and gray matter atrophy to predict worse outcomes.