Effects of Risperidone on Cytokine Profile in Drug-Naive First-Episode Psychosis

Background: There is robust evidence that schizophrenia is characterized by immune-inflammatory abnormalities, including variations on cytokine levels. The results of previous studies, however, are heterogeneous due to several confounding factors, such as the effects of antipsychotic drugs. Therefore, research on drug-naive first-episode psychosis (FEP) patients is essential to elucidate the role of immune processes in that disorder. Methods: The aim of this study is to compare cytokine levels (IL-2, IL-10, IL-4, IL-6, IFN-gamma, TNF-alpha, and IL-17) in drug-naive FEP patients both before and after treatment with risperidone for 10 weeks, and to investigate possible associations between cytokine levels and clinical responses to treatment and presence of depressive symptoms. It this study, we included 55 drug-naive FEP patients who had repeated measurements of cytokine levels and 57 healthy controls. Results: We found that FEP patients had significantly higher IL-6, IL-10 and TNF-alpha levels than healthy controls. After risperidone treatment, these three cytokines and additionally IL-4 decreased significantly. No significant difference was found between the post-treatment cytokine levels in FEP patients and in healthy controls, suggesting that these alterations in cytokine profiles are a state marker of FEP. No significant association was found between risperidone-induced changes in cytokines and the clinical response to treatment or the presence of depression. There was a significant inverse association between the risperidone-induced changes in IL-10 and the negative symptoms. Conclusions: In conclusion, our results show a specific cytokine profile in FEP patients (monocytic and regulatory T-cell activation) and suggest immunoregulatory effects of risperidone treatment, characterized by suppressant effects on monocytic, Th2, and T-regulatory functions.