LRP1 and Alzheimer disease: Clearance of Aβ from the brain occurs via active transport at the blood–brain barrier (BBB) and blood-cerebrospinal fluid barrier (BCSFB), in a process that is partially mediated by the low density lipoprotein receptor-related protein 1 (LRP1) [42], in addition to the removal of the peptide by several enzymes, mechanisms that are impaired in AD.