Unhealthy white matter connectivity, cognition, and racialization in older adults

• Published in: Alzheimer's & dementia 2024-03, Vol.20 (3), p.1483-1496
• Main Authors: Royse, Sarah K., Snitz, Beth E., Hengenius, James B., Huppert, Theodore J., Roush, Rebecca E., Ehrenkranz, Rebecca E., Wilson, James D., Bertolet, Marnie, Reese, Alexandria C., Cisneros, Geraldine, Potopenko, Katey, Becker, James T., Cohen, Ann D., Shaaban, C. Elizabeth
• Format: Article
• Language: English
• Subjects: African Americans; Aged; Alzheimer Disease - complications; Alzheimer's disease; Amyloid beta-Peptides - metabolism; Automation; Brain; Brain - metabolism; Brain research; cerebral small vessel disease; cerebrovascular lesions; Cognition; Cognition & reasoning; Cognitive Dysfunction - complications; connectome; Humans; Longitudinal studies; Magnetic Resonance Imaging; Measurement; Neurosciences; Older people; Pathology; Quality control; Racialization; Risk factors; White Matter - metabolism
• ISSN: 1552-5260; 1552-5279; 1552-5279
• DOI: 10.1002/alz.13494

INTRODUCTION White matter hyperintensities (WMH) may promote clinical Alzheimer's disease (AD) disparities between Black American (BA) and non‐Hispanic White (nHW) populations. Using a novel measurement, unhealthy white matter connectivity (UWMC), we interrogated racialized group differences in associations between WMH in AD pathology‐affected regions and cognition. METHODS UWMC is the proportion of white matter fibers that pass through WMH for every pair of brain regions. Individual regression models tested associations of UWMC in beta‐amyloid (Aβ) or tau pathology‐affected regions with cognition overall, stratified by racialized group, and with a racialized group interaction. RESULTS In 201 older adults ranging from cognitively unimpaired to AD, BA participants exhibited greater UWMC and worse cognition than nHW participants. UWMC was negatively associated with cognition in 17 and 5 Aβ‐ and tau‐affected regions, respectively. Racialization did not modify these relationships. DISCUSSION Differential UWMC burden, not differential UWMC‐and‐cognition associations, may drive clinical AD disparities between racialized groups. Highlights Unhealthy white matter connectivity (UWMC) in Alzheimer's disease (AD) pathology–affected brain regions is associated with cognition. Relationships between UWMC and cognition are similar between Black American (BA) and non‐Hispanic White (nHW) individuals. More UWMC may partially drive higher clinical AD burden in BA versus nHW populations. UWMC risk factors, particularly social and environmental, should be identified.