MAPT and Alzheimer disease: Accumulating evidence indicates that the pathology of AD is characterized by abnormal levels of extracellular senile plaques (SPs) containing insoluble amyloid-β (Aβ) peptides, abnormal levels of intracellular neurofibrillary tangles (NFTs) containing hyperphosphorylated tau [65,66,67], and abnormal iron deposition and oxidative damage [68,69,70] in the brains of patients.