MAPT and Alzheimer disease: In Alzheimer’s disease (AD), a progressive neurodegenerative disorder that is the most prevalent cause of dementia, histopathology is mainly characterized by extracellular plaques composed primarily of the Aβ peptide in fibrillar form, intracellular neurofibrillary tangles formed from hyperphosphorylated tau, and neuronal degeneration including extensive loss of cholinergic basal forebrain neurons.