MAPT and Alzheimer disease: Alzheimer disease (AD), the main cause of dementia in old age, is characterized by β-amyloid deposition forming plaques and amyloid angiopathy, and hyperphosylated tau in neurons with neurofibrillary tangles (NFTs) and pre-tangles, dystrophic neurites of senile plaques, and neuropil threads (Duyckaerts and Dickson, 2011; Ferrer, 2012; Braak and Del Tredici, 2015).