APP and Alzheimer disease: AD has been linked to hyperphosphorylation of the Tau protein (pTau), which destabilizes neuronal microtubules causing intracellular neurofibrillary tangles (NFT), and extracellular plaques caused by accumulation of Amyloid-β (Aβ) peptides, due to mutations in the amyloid precursor protein (APP) [37,39,40].