Equity and Transportability of Plasma ATN Phenotypes in a Population-Representative U.S. Aging Cohort

INTRODUCTION: Plasma biomarkers for Alzheimer's disease (AD) pathology promise scalable diagnostic access, yet their performance in diverse, population-representative cohorts remains uncharacterized. We evaluated equity and transportability of plasma amyloid-tau-neurodegeneration (ATN) biomarkers in a nationally representative U.S. aging cohort. METHODS: Cross-sectional analysis of 4,427 adults aged ≥50 years from the 2016 Health and Retirement Study Venous Blood Study. Plasma biomarkers (Aβ42/40, pTau181, NfL, GFAP) were classified using established ATN criteria. Survey weights produced population-representative estimates. Outcomes included biomarker-cognition associations, fairness metrics (sensitivity, specificity, predictive values) stratified by race/ethnicity and sex, and education-stratified analyses. RESULTS: Among 4,427 participants representing 36.6 million U.S. adults (weighted: 68 years, 55% female, 79% White), survey-weighted analysis revealed tau as the only biomarker maintaining robust cognitive associations (β=-0.74, p