In this genetic risk score study, we took a candidate gene approach by targeting genetic variants that have either been identified as having a clear link with risk for AD (i.e., APOE) or that have an important role in cognitive and brain functions in late adulthood and have a relatively common minor allele frequency (i.e., BDNF, COMT) but may have been previously undetected by GWAS due to small individual effect sizes. Here, APOE is linked to Alzheimer disease.