MAPT and Alzheimer disease: Currently, accumulated evidence has shown that the major pathological causes of AD are the abnormal extracellular deposition of senile plaques (SPs) mainly containing amyloid-β (Aβ) protein and intracellular accumulation of neurofibrillary tangles (NFTs) primarily formed by hyperphosphorylated tau in the brain (Metcalfe and Figueiredo-Pereira, 2010; Arvanitakis et al., 2011).