APOE and Alzheimer disease: While the cause of most AD cases is poorly understood (Reitz and Mayeux, 2014), genes encoding amyloid precursor protein (APP), presenilin 1 and presenilin 2 account for the majority of early-onset familial AD cases (Cheignon et al., 2018), whereas apolipoprotein E (APOE) is the main genetic risk factor in sporadic AD, especially APOE−ε4 (Morris et al., 2014; Clark and Vissel, 2018).