In 2019, a study conducted on 3xTg-AD mice showed that the phosphorylation of the Ser-422 site of the Tau protein, a marker of disease progression [44,45], is absent in 2-month-old mice [32], whereas the first brain lesions and cognitive decline appear at 6 months of age [30,31,32]. The gene discussed is MAPT; the disease is Mental deterioration.