MAPT and Alzheimer disease: AD is characterized by severe β-amyloid (Aβ) deposition in the brain (extracellular plaques), tau pathology (hyperphosphorylated tau causes neurofibrillary tangles), cell death of cholinergic neurons (loss of the neurotransmitter acetylcholine), astroglial and microglial activation, inflammation, and cerebrovascular damage (2).