PICALM and Alzheimer disease: Several players involved in Aβ clearance, and closely related to the BBB, are reduced in AD patients, including phosphatidylinositol-binding clathrin assembly protein (PICALM, allows for Aβ exocytosis across the luminal part of the BBB), P-glycoprotein (expressed on both sided of the BBB) and glucose transporter (GLUT)1 (Mooradian et al., 1997; Chiu et al., 2015; Zhao et al., 2015).