Biochemical markers in first-episode psychosis: A case-control study

It is being increasingly realized that immunological dysregulation and alteration of levels of cytokines play an important role in the etiology of psychotic symptoms, particularly of first-episode psychosis (FEP). Earlier studies have theorized that disrupted levels of interleukin-6 (IL-6) and interleukin-10 (IL-10) and other cytokines like C-reactive protein and tumor necrosis factor-alpha (TNF-α) play a role in symptom development in FEP patients. The study was done to evaluate serum levels of IL-6, IL-10, and IL-10-to-IL-6 ratio in FEP patients versus a healthy control population.

A case-control study was conducted with 120 individuals (60 FEP patients and 60 healthy controls age and sex matched) at a tertiary care facility in Western Maharashtra from January 2023 to December 2023. The serum levels of IL-6 and IL-10 were analyzed using enzyme-linked immunosorbent assay. Independent t-tests were used to analyze data for continuous variables and odds ratios (ORs) with 95% confidence intervals (CIs).

FEP patients exhibited IL-10 levels significantly higher than controls (6.39 ± 1.17 pg/mL vs 4.42 ± 0.58 pg/mL; p < 0.001) and lower IL-6 levels than controls (3.98 ± 0.56 pg/mL vs 4.31 ± 0.39 pg/mL; p < 0.001). The average IL-10-to-IL-6 ratio was also significantly different in FEP cases at 1.65 ± 0.46 and controls at 1.03 ± 0.11, with p <0.001. High IL-10 (OR = 2.85; 95% CI: 1.35-6.04) and high IL-10-to-IL-6 ratio (OR = 2.11; 95% CI: 1.02-4.39) were both significantly correlated with FEP, while high IL-6 levels were inversely correlated with FEP (OR = 0.41; 95% CI: 0.20-0.86). Mean body weight of FEP patients was also decreased significantly compared with controls (68.6 kg vs 72.7 kg; p < 0.001).

FEP patients have increased levels of IL-10, reduced levels of IL-6, and an increased IL-10-to-IL-6 ratio. Change in concentration of these cytokines could be involved in pathophysiology. The reduced body weight among the FEP patients may suggest underlying constitutional or metabolic factors that predispose them to the illness.