Recently, some epidemiological studies have focused on the association between ABCB1 gene variants and AD susceptibility, and these variants include the 3435C > T polymorphism, the 2677G > T/A polymorphism and the 1236C > T polymorphism23, 24, 25, 26, 27, 28, 29, 30, 31. This evidence concerns the gene ABCB1 and Alzheimer disease.