Despite the rare presence of amyloid plaques in the striatal region, the increase of striatal MeCP2 levels in 6-month-old APP/PS1 mice suggest that there may be noteworthy changes in epigenetic regulation by MeCP2 occurring throughout the pathogenesis of AD and the manifestation of cognitive dysfunctions in the APP/PS1 mice. This evidence concerns the gene PSEN1 and Alzheimer disease.