Estimation of IL-6, INFγ, and Lipid Profile in Suicidal and Nonsuicidal Adults with Major Depressive Disorder.

This study tested whether interleukin-6 (IL-6) and interferon-gamma (INF-γ) levels, as well as lipid profile, are associated with suicide attempts in adult patients with major depressive disorder (MDD), after controlling for related confounding factors. Plasma levels of IL-6 and INF-γ and lipid profile, including total cholesterol (TC), triglycerides (TGs), low-density lipoproteins (LDLs), and high-density lipoproteins, were measured in 60 patients meeting criteria of the fifth version of the Diagnostic and Statistical Manual of Mental Disorders for Major Depression (22 patients who attempted suicide and 38 patients who did not attempt suicide) and 30 healthy controls. Study participants were evaluated using the Hamilton Depression Rating Scale and the Beck's Suicidal Ideation Scale. Based on univariate analyses, IL-6, INF-γ, and TG plasma levels were significantly higher in both groups of depressed patients than healthy controls (P < 0.05), whereas TC and LDLs of patients who attempted suicide were significantly lower than patients who did not attempt suicide and healthy controls (P < 0.05). After adjusting for potential confounders, TC and LDLs were still significantly lower in patients who attempted suicide. With the exception of TC and LDLs, our findings do not support the hypothesis that IL-6 and INF-γ levels and lipid profile are associated with suicide attempts in adult patients with MDD. Identifying effective biological markers in patients who attempt suicide remains a challenge for future research.