There have also been reports that APOE ε4 causes earlier age of symptom onset (Blacker et al., 1997; Bettens et al., 2013), faster ventricular expansion (Roussotte et al., 2014), and greater rates of hippocampal atrophy and cortical thinning in subjects with MCI (Abushakra et al., 2020). This evidence concerns the gene APOE and hippocampal atrophy.