APOE and major depressive disorder: Participants in the highest quartile of RBC folate concentrations had 1 more point on the SMMSE at baseline than those in quartile 1 (β = +1.02, SE = 0.43, P = .02) after adjustment for sex, alcohol intake, smoking status, APOE genotype, education, BMI, depression, diabetes type 1 and 2, hypertension, history of cardiovascular disease, physical activity, and tHcy (Table 4).