Abstract
INTRODUCTION: Amyloid beta (Aβ), a hallmark of early Alzheimer's disease (AD), disrupts white matter (WM) microstructure, but its spatial patterns and transcriptomic links in cognitively normal individuals remain underexplored. METHODS: We compared the WM microstructure between Aβ-positive (Aβ+) and Aβ-negative (Aβ-) individuals at the cognitively normal stage. We investigated the relationship between the fibers and the cortical and subcortical regions to which they are connected, as well as the underlying gene expression. RESULTS: WM damage observed in Aβ+ individuals was characterized across eight fiber tracts, even prior to the evidence of atrophy and during the cognitive normal stage. This damage is primarily associated with cortical Aβ accumulation and may be linked to genes that regulate oligodendrocyte function and myelination. DISCUSSION: Cortical Aβ-related WM changes precede gray matter atrophy in preclinical AD, highlighting their potential as early biomarkers. Oligodendrocyte dysfunction and myelination pathways may underlie Aβ-driven WM vulnerability, offering targets for intervention. HIGHLIGHTS: WM microstructural changes precede gray matter atrophy in preclinical AD.Aβ-driven WM damage persists even after adjusting for age.WM microstructural damage is primarily linked to cortical Aβ burden in cognitively normal individuals.Oligodendrocytes and myelin underlie the vulnerability of WM-related to Aβ.