MAPT and Cognitive impairment: AD is one of major chronic neurodegenerative disorders that is histopathologically characterized by the intracellular neurofibrillary tangles (NFTs) that are composed of abnormally hyperphosphorylated tau and extracellular senile plaques that are accumulated of insoluble β-amyloid (Aβ), which result in a progressive cognitive impairment (Grundke-Iqbal et al., 1986; Alafuzoff et al., 1987).