APP and Alzheimer disease: AD is characterized by the deposition of amyloid plaques in the brain [3], [4], the major component of which is the β-amyloid protein (Aβ), a 40–42 amino-acid residue polypeptide [5], [6] that is generated from the β-amyloid precursor protein (APP) [7] by the β-site APP cleaving enzyme-1 (BACE1) [8], [9], [10], [11] and γ-secretase [12].