BACE1 and Alzheimer disease: Verubecestat (MK-8931), developed by the pharmaceutical company Merck, is a potent, selective, structurally unique BACE1 inhibitor that can reduce the plasma, cerebrospinal fluid (CSF) (Forman et al., 2012), and brain concentrations of Aβ40, Aβ42, and soluble APP beta protein (sAPPβ) (a direct product of the BACE1 enzymatic activity) in both healthy human subjects and AD patients (Forman et al., 2013).