APOE and Alzheimer disease: In many of the previous studies, participants recruited from regional or clinical cohorts included individuals at high-risk for AD with a higher prevalence of the APOE ε4 allele (e.g., 45.2% in AHEAD 3–45 study [35], 47.5% in the BioFINDER study [23], 53.9% in the ALFA + cohort [32] and 47.8% in the Wisconsin Registry for Alzheimer’s Prevention cohort [31]), whereas the APOE ε4 positivity in the J-TRC cohort was 20.2%, which is close to that of the general population in Japan and Asia [37].