It has been suggested that Aβ-induced aberrant epigenetic modifications may contribute to further Aβ accumulation and cell damage via overexpression of AD-associated genes such as APP, PSEN1, PSEN2, and BACE, as well as suppressed expression of Aβ degrading enzyme genes, thereby resulting in a vicious cycle [41]. This evidence concerns the gene PSEN2 and Alzheimer disease.