MAPT and Alzheimer disease: AD Neuropathological changes (ADNC) include extracellular aggregates of the amyloid beta (Aβ) peptides into plaques, intraneuronal formation of hyperphosphorylated paired helical filament (PHF) tau into neurofibrillary tangles, and neuritic plaques that are composed of both extracellular Aβ and PHF tau in neuronal processes.