Fig. 2. Schematic presentation showing thebrain and blood vessel compartment and the ways of Aβ clearance pathways. The blood-brain barrier (BBB) is a separation of circulating blood from the brain interstitial fluid (ISF) in the central nervous system (CNS). It is composed of thin and flat endothelial cells inthe capillaries. This barrier also includes athick basement membrane, smooth musclecells and astrocytic endfeet. This barrier restricts the diffusion of most materials into the cerebral ISF. See text for details. APP: Amyloid precursor protein, ADE: Amyloid-β degradation enzyme, LRP: Low-density lipoprotein receptor-related protein, RAGE: Receptor for advanced glycation end product, CSF: Cerebrospinal fluid.