Both the CYP46A1 rs754203 (OR = 1.528, P = 0.018) and MTHFR rs1801133 (OR = 1.557, P = 0.009) polymorphisms showed significant associations with the risk of AD among non-ApoE ε4 carriers, but not among ApoE ε4 carriers (P = 0.284 and P = 0.086). This evidence concerns the gene CYP46A1 and Alzheimer disease.