APOE and Alzheimer disease: Based on prior studies—including work from our group—suggesting that older age, sex, and carrying multiple risk factors contribute to the degree of presymptomatic AD-related neural damage, we also tested for interactions between age and risk (APOE4 or parental family history) (Ryan et al., 2011), sex and risk (Damoiseaux et al., 2012), and APOE4 and parental family history (Bendlin et al., 2010).