In the young adult MDD group, IL-1β in the serum was positively correlated with the BDI (p = 0.0007), STAI-X-1 (p < 0.0001), HAMD-17 (p = 0.0111), and BHS (p < 0.0001) scores but negatively correlated with the RSE (p = 0.0005) and RAS (p = 0.0046) scores. Here, IL1B is linked to major depressive disorder.