PSEN1 and Alzheimer disease: Conversely, S-adenosylmethionine supplementation was able to counteract the exacerbation of AD-like features, preventing PSEN1 hypomethylation and overexpression, thus reducing β- and γ-secretase activities, Aβ production and amyloid plaques spreading to control-like values in TgCRND8 mice in a B-deficient condition [60].