MAPT and Alzheimer disease: Three neuropathological mechanisms postulated in AD are: i) formation of extracellular Aβ plaques by insoluble amyloid proteins' aggregate, ii) formation of NFTs (disorganized bundles of filaments in the neuronal cytoplasm) by hyperphosphorylated tau proteins, and iii) neuronal loss as the aftermath of the Aβ plaques and NFTs (Revett et al., 2013).