MAPT and Alzheimer disease: AD is neuropathologically characterised by the aberrant aggregation of amyloid‐β (Aβ) into extracellular plaques as well as hyperphosphorylated tau protein into intraneuronal neurofibrillary tangles (NFTs) and dystrophic neurites surrounding the plaques, which together represent the hallmarks of the disease (Braak & Braak, 1991; Thal et al, 2002).