ABCG2 interacts directly with Aβ and has been found to promote the cellular flow of Aβ40and Aβ42in the BBB.60, 61Although studies in mouse and human AD brains have reported that upregulation of BCRP is effective in reducing Aβ accumulation,62, 63there are also studies reporting that there is no difference between BCRP levels in healthy and AD individuals.59 This evidence concerns the gene ABCG2 and Alzheimer disease.