Assessment of serum inflammatory cytokines in first-episode psychosis: Cross-sectional study

Abstract

Background: Chronic low-grade systemic inflammation is implicated in the pathophysiology of schizophrenia, particularly in its early stages. Pro-inflammatory and anti-inflammatory cytokines have been implicated, particularly interleukin (IL) 6, 8 and 10.
Aim: To investigate the association between serum inflammatory cytokines (IL-6, IL-8 and IL-10) and first-episode psychosis (FEP).
Setting: The study was at five clinical sites in KwaZulu-Natal, South Africa.
Methods: This study was an observational, cross-sectional sub-analysis of data derived from a larger longitudinal cohort study of individuals with FEP. In this analysis, we included HIV-negative participants who were 18 years to 45 years old and had less than 6 weeks of antipsychotic exposure. Measures included socio-demographics (age, sex), body mass index (BMI), psychiatric diagnosis (Mini International Neuropsychiatric Interview, MINI), psychosis severity (Positive and Negative Syndrome Scale, PANSS), depressive symptoms (Patient Health Questionnaire-9, PHQ-9), substance use (WHO Alcohol, Smoking and Substance Involvement Screening Test, WHO-ASSIST), childhood trauma (Childhood Trauma Questionnaire, CTQ), and serum cytokines (Multiplex ELISA).
Results: The sample comprised 58 participants, predominantly men (83%), with high rates of lifetime alcohol use (88%) and at least one type of childhood trauma (66%). There was a statistically significantly higher cytokine expression with current alcohol use: IL-6 (p = 0.04), IL-8 (p = 0.01) and IL-10 (p = 0.03). There was also a statistically significant association between lifetime alcohol and tobacco use and elevated IL-10 (p = 0.00 and p = 0.04, respectively). There was no statistically significant association between PANSS, PHQ-9, CTQ, BMI or cannabis and interleukins.
Conclusion: The study concludes that there is some evidence of immunological dysfunction at baseline in treatment-naïve persons diagnosed with FEP.
Contribution: This study contributes novel data on inflammatory cytokine profiles in individuals with FEP in a South African context, an under-represented population in psychoneuro-immunology research.