MAPT and Alzheimer disease: Alzheimer’s disease (AD) is the most common cause of dementia among older people and is characterised by the occurrence of extracellular amyloid deposits (senile plaques) of the amyloid beta (Aβ) peptide and by intraneuronal aggregates of hyperphosphorylated tau protein in structures named neurofibrillary tangles (NFTs) [108].