Functional alterations in white-gray matters bipartite network in preclinical Alzheimer’s disease

Motivation: The significance of changes in functional connectivity (FC) measures involving white matter (WM) at preclinical stages of Alzheimer’s disease (AD) remains unclear. Goal(s): Our goal was to reveal alterations in correlations in BOLD signals between WM and gray matter (GM) in the AD continuum, focusing on preclinical AD. Approach: We used a novel bipartite graph model to evaluate network properties at multi-scales and compared preclinical AD, AD subjects with controls. Results: We found declines in local specific WM-GM FC and WM FC density, without a manifest decline in global efficiency of WM-involved functional networks in the preclinical AD group. Impact: Our observation of a decline in local WM-GM FC and WM FC density but an intact global efficiency of functional networks in preclinical AD may help explain why cognition remains normal despite the presence of pathology during the preclinical stage.