MAPT and Alzheimer disease: Alzheimer’s disease, a degenerative brain disease, is the most common cause of dementia, with clinical features including gradual decline of cognitive function, amnesia, behavioral and personality changes, and pathological features including extracellular Aβ plaques and intracellular NFT intraneuronal deposition, tau protein degeneration, and severe neuronal loss in the brain tissue (Saxena, 2010).