Most of the studies support that P-glycoprotein is important for Aβ1–40 and Aβ1–42 clearance, and that dysfunction of this process might lead to AD development (Lam et al., 2001; Vogelgesang et al., 2002; Vogelgesang et al., 2004; Cirrito et al., 2005; Kuhnke et al., 2007; Silverberg et al., 2010). Here, ABCB1 is linked to Alzheimer disease.