Polygenic risk score of Alzheimer's disease is associated with cognitive trajectories and phenotypes of cerebral organoids

INTRODUCTION Polygenic risk score (PRS) identifies individuals at high genetic risk for Alzheimer's disease (AD), but its utility in predicting cognitive trajectories and AD pathologies remains unclear. We optimized PRS (optPRS) for AD, investigated its association with cognitive trajectories and AD phenotypes of cerebral organoids. METHODS Using genome‐wide association study (GWAS) summary statistics from a European population, we developed optPRS to predict AD in Korean individuals (n = 1634). We analyzed the association between optPRS and cognitive trajectories (n = 771). We generated induced pluripotent stem cell–derived cerebral organoids from patients with high (n = 3) and low (n = 4) optPRS to evaluate amyloid beta (Aβ) and phosphorylated tau (p‐tau) levels. RESULTS OptPRS predicted AD dementia and Aβ positivity, independent of apolipoprotein E ( APOE ). Higher optPRSs correlated with rapid cognitive decline. Cerebral organoids from the high optPRS group exhibited increased Aβ insolubility and p‐tau levels. CONCLUSION OptPRS predicted cognitive decline and AD phenotypes of cerebral organoids, supporting its use in risk assessments and drug‐screening platform. Highlights Optimized polygenic risk scores (optPRSs) improve the prediction of Alzheimer's disease (AD) dementia and amyloid beta positivity (Aβ+). High optPRS is associated with faster cognitive decline, particularly in Aβ+. Induced pluripotent stem cell (iPSC)–derived cerebral organoids from high optPRSs show high Aβ insolubility and phosphorylated tau (p‐tau). PRS genetic risk stratification provides insight into AD progression and pathology.