Considering the excellent reviews on the causal associations of Aβ and tau with mitochondrial dysfunctions in AD [34,35,36,37], we do not intend here to provide a compendium of the countless studies on the alterations of mitochondria, whose extensive loss aggravates the disease development, but we want make a quick overview of some of the literature data, the most significant, which will be useful for introducing the main topic we intend to treat. This evidence concerns the gene MAPT and Alzheimer disease.