Deficits in odor identification and memory have also been observed to be associated with the genetic risk factor for AD, the apolipoprotein e4 (APOE) allele (Murphy et al., 1998; Gilbert and Murphy, 2004a, b; Calhoun-Haney and Murphy, 2005; Handley et al., 2006; Olofsson et al., 2010, 2020). This evidence concerns the gene APOE and Alzheimer disease.