O10.5. META-ANALYSIS OF CYTOKINE LEVELS AND PSYCHOPATHOLOGY IN SCHIZOPHRENIA

Abstract

Background: Schizophrenia is associated with aberrant blood levels of inflammatory markers. There is some evidence that treatment with adjunctive anti-inflammatory medications in schizophrenia may be associated with improvement in psychopathology, particularly in patients with abnormal levels of inflammatory markers. However, relationships between inflammatory marker levels and psychopathology in schizophrenia have not been systematically investigated. We performed a meta-analysis of the correlation between blood cytokine levels and psychopathology in schizophrenia. Methods: We identified articles by systematic searches of PubMed, PsycINFO, and Web of Science databases, and the reference lists of identified studies. We included studies, in English, that reported correlations between blood inflammatory markers and psychopathology scores in patients with schizophrenia or provided previously unpublished correlative data. Out of 246 potential studies, 73 studies, comprising 6112 patients, met inclusion criteria. 38% of included studies provided at least some previously unpublished data. Data were pooled using a random effects approach. Results: In all studies, C-reactive protein (CRP) and interleukin (IL)-18 were significantly correlated with multiple domains of psychopathology (effect sizes [ESs]=0.17-0.25). In inpatients, IL-6, CRP, IL-17, IL-18, and interferon (IFN)-γ were significantly correlated with multiple domains of psychopathology (ESs=0.13-0.30). In first-episode psychosis, IL-1β (ES=0.23) and IL-2 (ES=0.17) were significantly correlated with total psychopathology. Following antipsychotic treatment, changes in IL-6 levels were significantly correlated with changes in total psychopathology (ES=0.19). Discussion: Modest, but significant, correlations between inflammatory markers and psychopathology complement and extend previous findings, suggesting that there may be a biological gradient for these associations. These findings have important implications for our understanding of the pathophysiology and potentially the treatment of schizophrenia.