However, the contribution of BBB-associated pericytes compared to endothelial trans-vascular transport to Aβ clearance at the BBB still remains elusive, particularly, whether pericytes can contribute to removal of aggregated Aβ from brain capillaries, which develop cerebral amyloid angiopathy (CAA) in AD [8], and whether removal of Aβ aggregates by pericytes requires apoE, and if so, is Aβ clearance on pericytes apoE isoform-specific? This evidence concerns the gene APOE and cerebral amyloid angiopathy.