APOE and Cerebral cortical atrophy: Considering the impact of the APOE ε4 genotype on the cognition, and cortical atrophy in the MCI (Farlow et al., 2004; Hämäläinen et al., 2008; Risacher et al., 2013), we evaluated the main effect of APOE ε4 genotype on the cortical atrophy within and across the groups.