Fixel-based analysis of white matter fiber characteristics and cognitive dysfunction in Alzheimer’s disease

Motivation: The relationship between white matter (WM) structure, Alzheimer's disease (AD) progression, and cognitive dysfunction remains unclear. Goal(s): To identify WM fiber differences between healthy controls (HC), mild cognitive impairment (MCI), mild AD, moderate AD, and WM fiber characteristics correlation with cognitive dysfunctions. Approach: Fixel-based analysis (FBA) was used to measure WM fiber density (FD), fiber cross-sectional area (FC), and fiber density and cross-section (FDC) across 27 HC, 19 MCI, 19 mild AD, and 25 moderate AD participants. Results: AD patients showed significant reductions in FD, FC, and FDC in various WM fiber tracts. Some of the reductions also correlated with lower cognitive scores. Impact: This study shows that FBA-measured WM fiber characteristics correlate with AD severity and cognitive decline. These metrics may serve as biomarkers for monitoring disease progression and aiding in the diagnosis of AD.