Higher rates of depressive symptoms (OR = 1.41, 95%-CI = 1.02-1.95) and higher burden of the APOE-ε4 allele (OR = 3.29, 95%-CI = 1.51-7.40) predicted objective cognitive impairment, regardless of age, sex, years of formal education, time since infection, and medication for diabetes or hypertension. Here, APOE is linked to diabetes mellitus.