MAPT and Alzheimer disease: Alzheimer’s disease (AD) is characterized by intraneuronal and extracellular accumulation of amyloid-β peptide (Aβ), intracellular neurofibrillary tangles (NFTs), the major component of which is hyperphosphorylated tau protein (p-tau), disruption of both excitatory amino acid and cholinergic neurotransmission, and loss of vulnerable neurons, notably forebrain cholinergic neurons that project to the cerebral cortex and hippocampus.