APOE and Alzheimer disease: The posterior cingulate gyrus is affected in early stages of AD and this cortical region shows alterations in people at increased risk for AD, including APOE4 carriers (Reiman et al., 1996; Valla et al., 2010) and in adults with parental family history of AD (Johnson et al., 2007; Mosconi et al., 2007; Scarmeas et al., 2004; Small et al., 2000).