APOE and major depressive disorder: For the 40s cohort, there was marginal evidence for APOE*ε4+ conferring protection for 4-year risk for any depression status (OR = 0.65 (95% CI 0.41–1.01), P = 0.056) and 8-year risk for depressive symptomology (IRR = 0.92 (95% CI 0.84–1.01), P = 0.066).