IC‐P‐014: LONGITUDINAL INVESTIGATION OF CONCORDANT AND DISCORDANT AMYLOID CSF/PETBIOMARKERS REVEALS CSF‐FIRST AND PET‐FIRST PATHWAYS OF AMYLOID ACCUMULATION

reference) was averaged from a cortical region of interest (ROI) to assess Ab. Cortical thickness was estimated from T1 using FreeSurfer in an AD-signature meta-ROI. Log-normalized global WMH volume (lnWMH) was calculated from FLAIR corrected by head size. We assessed racial/ethnic group differences using ttests, bivariate associations between VRFs and imaging variables using linear regression, and multivariate contributions to cortical thickness and Ab using a stepwise model building approach. Results: We observed baseline VRF differences between ethnic groups, such that African-Americans exhibited significantly greater ASCVD and FRS (marginal) than Caucasians. No significant racial differences in imaging measures of Ab, cortical thickness, orWMH volume were observed (Table 1). Higher baseline VRFs were associated with reduced cortical thickness and greater WMH (Figure), but not Ab. In multivariate models, we found that age and APOE-ε4 carriage were associated with brain Ab (Table 2); higher lnWMH, ASCVD, and brain Ab predicted cortical thickness independent of each other and of age. Conclusions: In contrast with recent studies showing Ab-PET racial differences, our preliminary single-site results suggest that African-Americans were no more likely to be Ab+ than Caucasians. Higher baseline VRFs were associated with increased WMH and reduced cortical thickness, but not elevated brain Ab. ASCVD, lnWMH, and Ab predicted cortical thickness, suggesting the convergence of multiple vascular and AD processes underlying neurodegeneration. Ongoing analyses will examine racial/ethnic differences in specific VRF pathways, imaging markers, and cognition.