Immune dysfunction in bipolar disorder and suicide risk: is there an association between peripheral corticotropin-releasing hormone and interleukin-1β?

ObjectiveThe aim of the present study was to investigate the relationship between peripheral levels of corticotropin-releasing hormone (CRH) and interleukin-1 (IL-1) in individuals with bipolar disorder (BD) with and without suicide risk (SR), and controls. MethodsA total of 120 young adults (40 controls, 40 subjects with BD without SR, and 40 subjects with BD with SR) were enrolled from a population-based study carried out in the city of Pelotas, Brazil. BD and SR were assessed through the Mini International Neuropsychiatric Interview (MINI 5.0), and peripheral markers were evaluated by enzyme-linked immunosorbent assay (ELISA). ResultsLevels of CRH were significantly lower both in subjects with BD without SR (p=0.04) and subjects with BD with SR (p=0.02) when compared to controls. However, levels of IL-1 were increased in subjects with BD with SR (p=0.05) when compared to controls. Sociodemographic and clinical variables, current mood episode, and use of psychiatric medications were not associated with changes in these markers. No correlation was found between peripheral levels of CRH and IL-1 (p=0.60) in the population or in the BD with SR group (p=0.88). ConclusionsThese results suggest that peripheral mechanisms linking stress hormones and the immune system might be critical patterns involved in suicidal behavior associated with BD.