In our analysis, we utilized receiver operating characteristic (ROC) curves to assess the ability of predefined variables to effectively distinguish between MMD + SA, MDD-SA, and healthy control groups (as shown in Table 3).When examining the ROC curve for the discrimination of MMD + SA vs. MDD-SA based on BDNF levels, we observed an area under the curve (AUC) of 0.576 (95% confidence interval [CI] 0.429–0.722, p = 0.313). This evidence concerns the gene BDNF and major depressive disorder.