Introduction Greater understanding of the role of cytokines in interactions between the nervous and immune systems has led to integrative and explanatory models for neuropsychiatric disorders. Our study aimed to examine peripheral inflammatory cytokines and immune balance in generalised anxiety disorder (GAD). Methods A case-controlled cross-sectional study investigated associations between psychological and biological variables. 54 patients with GAD and 64 healthy controls were recruited. Participants completed self-report measures of anxiety and depression. A panel of two pro-inflammatory and two anti-inflammatory cytokines were measured using multiplex technology. Results Case-control logistic regression analyses revealed significant differences in serum levels of IL-10, TNF- α , and IFN- γ between GAD and control groups after adjusting for age, gender and body mass index: these group differences were independent of the presence or degree of depression. Comparison of pro- and anti-inflammatory cytokine ratios indicated that there were significantly higher ratios of TNF- α /IL10, TNF- α /IL4, IFN- γ /IL10, and IFN- γ /IL4 in the GAD group compared to the control group. Conclusions This study is the first to investigate both pro- and anti-inflammatory cytokines and their balance in patients with GAD in comparison to healthy controls. The findings indicate a relatively increased pro-inflammatory response and diminished anti-inflammatory response and provide the first demonstration of a Th1/Th2 cytokine imbalance in GAD. The changes in serum cytokine levels in GAD were independent of the presence of depression.
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