ApoE ε2/ε4, ε3/ε4 and ε4/ε4 were significantly associated with AD (ε2/ε4: OR 1.521, 95% CI [1.270–1.823], P < 0.001; ε3/ε4: OR 2.491, 95% CI [2.267–2.738], P < 0.001 and ε4/ε4: OR 5.481, 95% CI [4.801–6.257], P < 0.001). This evidence concerns the gene APOE and Alzheimer disease.