Stroke was strongly associated with dementia in both age groups (unadjusted OR = 11.6, 95% C.I. = 4.5–29.7 for the younger group; OR = 7.3, 95% C.I. = 4.3–12.3 for the older group, P < .001), even after adjustment for sex, age, education, diabetes, APOE genotype, folate, vitamin B12, and tHcy (OR = 22.5., 95% C.I. = 6.0–84.4 for the younger group; OR = 7.5, 95% C.I. = 4.0–14.0 for the older group). The gene discussed is APOE; the disease is diabetes mellitus.