In this investigation, the frequency of all ApoE genotypes, including ε2/ ε2, ε2/ ε3, ε2/ ε4, ε3/ ε3, ε3/ ε4, and ε4/ ε4, was not significantly different between the AD-A and AD-NA groups (P>0.05), which demonstrated that ApoE genotype had no influence on apathy in AD patients. Here, APOE is linked to Alzheimer disease.