MAPT and Alzheimer disease: Various factors contribute to AD-related dementia and impairment of cognitive functions, however, extracellular amyloid beta (Aβ) plaques and intracellular aggregates of hyperphosphorylated tau proteins also called neurofibrillary tangles (NFTs) are the two major histopathological hallmarks of AD (Mayeux and Stern, 2012; Xu et al., 2012; Kametani and Hasegawa, 2018; Janeiro et al., 2021).