APP and Alzheimer disease: One of the most accredited theories is the amyloid cascade hypothesis [1], which identifies as the main cause of AD progression the misfolding and the extracellular aggregation of Amyloid-β (Aβ) peptides from the cleavage of amyloid precursor protein (APP), as well as the intracellular deposition of the misfolded tau protein in neurofibrillary tangles.