APOE and Alzheimer disease: The APOE ε4 allele is specifically linked to a higher likelihood of developing AD and a less favourable reaction to cholinesterase inhibitors, which are routinely employed for AD symptom management (Giri et al., 2016; Van Cauwenberghe et al., 2016; Braak and Del Tredici, 2015; Spillantini et al., 1997; Stewart et al., 1997).