While levels of proinflammatory mediators are increased, ABCB1/Abcb1 and ABCG2/Abcg2 expression and associated protein activity levels are decreased in animal models of Alzheimer’s disease as well as in patients with Alzheimer’s disease (Vogelgesang et al., 2002, 2004; Hartz et al., 2010c, 2012, 2018; Wijesuriya et al., 2010; Jeynes and Provias, 2011b; van Assema et al., 2012b; Mehta et al., 2013; Carrano et al., 2014; Chiu et al., 2015; Wang et al., 2016; Bauer et al., 2017; Kannan et al., 2017; Shubbar and Penny, 2018; Al-Majdoub et al., 2019). This evidence concerns the gene ABCG2 and early-onset autosomal dominant Alzheimer disease.