APOB and major depressive disorder: Using ApoB quartiles as the independent variable, logistic regression showed that compared with Q1, the risk ratios for depression were 1.53, 3.00, and 7.90 in Q2–Q4 in the unadjusted model, and 1.26, 2.26, and 5.41 in the fully adjusted model (all P < 0.001 for Q3–Q4).