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