Background: Different studies have suggested an involvement of inflammatory processes in the pathophysiology of psychiatric disorders. Cytokines have received special attention as potential mediators of the interaction between immune and neuroendocrine systems. Previous reports have suggested a proinflammatory state associated with both Bipolar Disorder and Schizophrenia. However, they did not compare cytokine levels between the two diagnosis..
Methods: We recruited 20 manic patients with previous history of BD and 20 patients with SZ. A healthy comparison group included 26 healthy volunteers. Cytokines TNF-α, IL-6, and IL-10 were examined by flow cytometry.
Results: Both TNF-α and IL-6 were significantly increased in BD and SZ when compared with controls. Patients with SZ had higher levels of these two pro-inflammatory cytokines than manic patients. IL-10 was significantly decreased in patients with SZ but increased in BD if compared with controls. The significance did not change when patients were separated by gender and there was no correlation with antipsychotic dose and cytokine levels in patients with SZ.
Discussion: These findings suggest that both mania and SZ are associated with a proinflammatory state. Interestingly, anti-inflamatory factor IL-10 was increased in BD but decreased in SZ, which may suggest a different pattern of inflammatory balance between these two disorders or might be explained by the anti-inflammatory effect of mood stabilizers. This study provides further support to investigate the immune system as a target for future treatment development as well as the role of cytokines as a possible biomarker for disease activity or treatment response.