Since the Apolipoprotein E (APOE) ε4 allele, a genetic risk factor for sporadic AD (Bertram et al., 2010), is associated with amyloid pathology (Jansen et al., 2015) and functional and structural brain changes (Cherbuin et al., 2007; Trachtenberg et al., 2012) in cognitively normal subjects we also examined whether APOE ε4 modified the relationship between amyloid and gray matter networks. The gene discussed is APOE; the disease is Alzheimer disease.