MAPT and Alzheimer disease: Several studies in mice have shown that the interaction of ultrasound with microbubbles transiently opens the BBB, allowing unidentified blood-borne factors and exogenously added antibodies or antibody fragments to enter the brain where they ameliorate the two defining pathologies of AD, Aβ and tau deposition, by an incompletely understood mechanism that involves microglia (Jordão et al., 2010, 2013; Leinenga and Götz, 2015).