BACE1 and Alzheimer disease: Cognitive impairments, characteristic of AD, correlate closely with the loss of synapses and current knowledge suggests that excess amyloid-β (Aβ) causes synapse dysfunction by impairing synapse maintenance, at least in part, through causing dysfunction of Wnt signaling.6,7 Compromised Wnt signaling may also be associated with AD through loss of blood–brain barrier (BBB) integrity8 and Aβ generation through β-secretase (BACE1) expression.9