Structural Carotid Atherosclerosis and Mild Behavioral Impairment: A Cross-Sectional Study in a Community-Dwelling Population.

Mild behavioral impairment (MBI) is a late-life neuropsychiatric syndrome proposed as an early clinical manifestation of neurodegenerative disease. Vascular pathology contributes to late-life cognitive and behavioral changes; however, its relationship with MBI remains insufficiently characterized. This cross-sectional study investigated whether structural carotid atherosclerosis is associated with MBI and its symptom domains in 563 community-dwelling, dementia-free adults aged ≥ 50 from the Kaohsiung Atherosclerosis Longitudinal Study between 2018 and 2021. MBI was assessed using the informant-rated Mild Behavioral Impairment Checklist, evaluating apathy/motivation, affective dysregulation, impulse dyscontrol, social inappropriateness, and abnormal thought/perception. Structural carotid atherosclerosis was evaluated by ultrasound, assessing plaques and mean carotid intima-media thickness (cIMT) across the common carotid artery (CCA), bifurcation, and internal carotid artery. Advanced structural atherosclerosis was defined as the presence of plaque or top-quartile cIMT. Multivariable regression models examined associations between carotid atherosclerosis and MBI severity, adjusting for demographics, medical conditions, and global cognition. Advanced structural atherosclerosis was independently associated with higher MBI scores (β = 0.143, p = 0.001). Elevated cIMT-but not plaque-was significantly associated with MBI severity. Segment-specific analyses showed increased CCA IMT was the only vascular marker significantly related to MBI total scores. Furthermore, advanced structural atherosclerosis was associated with increased odds of decreased motivation, impulse dyscontrol, and social inappropriateness. In conclusion, structural carotid atherosclerosis, particularly elevated CCA IMT, is associated with greater MBI symptom burden in middle-to-older adults. Subclinical vascular pathology may contribute to early neurobehavioral changes, highlighting the importance of vascular health in identifying individuals at risk for neurodegenerative disorders.