BACE1 and Alzheimer disease: The major component of plaques found in the brains of patients with Alzheimer ́s disease (AD) are 40–42 amino acids long amyloid beta (Aβ) peptides derived from the amyloid precursor protein (APP) by enzymatic cleavage, first with β-secretase (BACE1) and then by γ-secretase [1, 2].