Apolipoprotein E (APOE) gene alleles are the leading genetic risk factors for AD, with at least fourfold increased AD risk for each APOE ε4 allele (abbreviated APOE4, ε4, or E4), and increased severity of aggregate‐associated neuropathology for AD carriers of APOE4 alleles (Neu et al., 2017; Parker et al., 2005). This evidence concerns the gene APOE and Alzheimer disease.