The apolipoprotein ε4 (APOE4) is the most well-evidenced risk gene for Alzheimer’s disease (AD; Corder et al., 1993) and is related to in vivo AD pathologies such as β-amyloid (Aβ) accumulation (Morris et al., 2010), reduced hippocampal volume (Hashimoto et al., 2001), and decreased AD-signature region cerebral glucose metabolism (AD-CM; Small et al., 1995; Lowe et al., 2014). Here, APOE is linked to Alzheimer disease.