APOE and Alzheimer disease: Brain changes in AD occur several years before memory symptoms appear, and accordingly, risk factors for AD are also associated with white matter changes, including apolipoprotein E e4 genotype (APOE4) (Bartzokis et al., 2006; Bartzokis et al., 2007; Filippini et al., 2009; Heise et al., 2011; Honea et al., 2009; Nierenberg et al., 2005; Persson et al., 2006; Ryan et al., 2011; Westlye et al., 2012) and parental family history of AD (Bendlin et al., 2010; Xiong et al., 2011).