Genetic factors, such as APOE ε4 carrier status and polygenic risk scores (PRS), influence AD risk, but their roles in cognitive decline among Asian populations remain unclear.<h4>Objective</h4>To evaluate whether APOE ε4 carrier status and a non-APOE polygenic risk score (PRS_ADnapoe) are associated with age-related cognitive decline in community-dwelling older adults in Taiwan.<h4>Design, setting, and participants</h4>This prospective cohort study used data from 2 assessment waves of the Healthy Aging Longitudinal Study in Taiwan, spanning 2009 to 2019. Here, APOE is linked to Alzheimer disease.