APOE and Alzheimer disease: Nigerian people have the highest frequency of the APOE4 allele, which, however, is not found to be associated with an increased risk for AD, likely due to their low cholesterol levels (Sepehrnia et al., 1989; Notkola et al., 1998; Kivipelto et al., 2002; Gureje et al., 2006; Walters et al., 2023; Zhang et al., 2023).