Cerebral small vessel disease burden relates to cognitive decline via impaired amyloid clearance in the general population.

Our aim is to examine the interplay between cerebral small vessel disease (CSVD) pathology, Alzheimer's disease (AD) related amyloid-β (Aβ) clearance, and cognition in general population. Cross-sectional structural equation modeling (SEM) was conducted to evaluate CSVD burden, cognition, and plasma Aβ42/40 ratios in 1026 participants without dementia from a prospective community-based cohort. CSVD burden was quantified using five established MRI markers, while cognition was assessed with the Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), verbal fluency test, and reverse digit span. Models were adjusted for age, sex, education, body mass index, vascular risk factors (hypertension, diabetes mellitus, hyperlipidemia, and smoking), antihypertensive medication use, and APOE4 carrier status. Greater CSVD burden was significantly associated with poorer cognition (B = -2.607 ± 1.016, β = -0.167, p = 0.010), with white matter hyperintensity volume (∆R2 = 0.3%, p = 0.016) and brain parenchymal fraction (∆R2 = 0.4%, p = 0.019) contributing most strongly. CSVD burden was also negatively correlated with plasma Aβ42/40 ratios (B = -0.280 ± 0.074, β = -0.140, p < 0.001), which partially mediated the CSVD-cognition association (B = -0.241 ± 0.087, β = -0.015, p = 0.006). These findings underscore potential CSVD involvement in AD-related pathology across aging.