IL18 and major depressive disorder: All patients received conventional treatment 1 d after admission, patients' serological indicators were measured before treatment, and after 30 d of follow-up, the patients were divided into the survival group (SG) and death group (DG) according to their clinical outcomes, the Beck's Depression Inventory (BDI) scores of the surviving patients were investigated, the correlation of IL-18, BDNF, and IL-1β levels with depression was analyzed by R analytics, and the correlation of IL-18, BDNF, and IL-1β levels with prognosis was analyzed by ROC curve analysis.