Serum IL-6 as a Potential Biomarker of Metabolic Status in Schizophrenia Patients and Its Correlation with Psychotic Symptoms

Objectives: This study aimed to investigate the serum IL-6 level in schizophrenia patients, considering disease chronicity and metabolic status, and to examine its correlation with psychotic symptom scores. The present study also evaluated the diagnostic value of serum IL-6 as a peripheral biomarker for assessing the metabolic health of schizophrenia patients. Methods: Serum IL-6 levels were measured using enzyme-linked immunosorbent assay (ELISA) in 92 schizophrenia patients [44 First Episode Drug Naive (FEDN), 48 chronic schizophrenia (CSZ) patients] and 32 healthy controls. Patients were also stratified into high-risk and no-risk cohorts based on their metabolic status. Psychotic symptoms were assessed with the Positive and Negative Syndrome Scale (PANSS). Findings: Serum IL-6 levels were significantly higher in schizophrenia patients compared to healthy controls (p<0.001), with no difference between FEDN and CSZ patients (p=0.475). Elevated IL-6 levels were observed in patients in high-risk group compared to those in no-risk group (p<0.001). There was a positive correlation between serum IL-6 levels and BMI (r=0.557, p<0.001), G score (r=0.244, p=0.01), and total PANSS score (r=0.228, p=0.02). Similar associations were found in CSZ patients. The ROC curve analysis showed that serum IL-6 has strong diagnostic potential for distinguishing schizophrenia patients in the high-risk group from those in the no-risk group (AUC=0.875, 95% CI: 0.781-0.969, p<0.001), suggesting its value as a biomarker. Novelty: This study highlights the stable role of serum IL-6 in schizophrenia patients regardless of disease chronicity. The findings suggest that serum IL-6 levels were significantly associated with disease severity as measured by PANSS and metabolic health of schizophrenia patients, providing new insights into its prognostic and diagnostic utility. Early identification and targeted management of high-risk groups can improve patient outcomes and quality of life. Keywords: Schizophrenia, IL-6, FEDN, Chronic, PANSS, Metabolic status, Biomarker