Introduction: Previous investigations have demonstrated that major depression is associated with particular patterns of cytokine signalling. The primary aim of this study was to examine peripheral pro-inflammatory and anti-inflammatory cytokines and immune balance in Generalised Anxiety Disorder (GAD).

Methods: A case-controlled cross-sectional study design was employed: 54 patients with GAD and 64 healthy controls were recruited. Participants completed self-report measures of anxiety and depression. 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, body mass index, smoking and alcohol consumption: these group differences were independent of the presence or degree of depression. Comparison of pro-inflammatory to 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 decreased anti-inflammatory response and provide the first demonstration of an altered cytokine balance in GAD. Serum cytokine levels in GAD were independent of the presence of depression.

Keywords: Anti-inflammatory cytokine; Cytokine ratios; Generalised Anxiety Disorder; Inflammation; Pro-inflammatory cytokine.

Conflict of interest statement

Financial Disclosures

In the past two years, Professor David S. Baldwin has received financial support from H. Lundbeck A/S (advisory board attendance), AstraZeneca, Janssen and Pfizer (lecture fees), and the UK Ministry of Defence (research ethics committee membership). The other authors including Dr Ruihua Hou, Professor Clive Holmes, Dr Matthew Garner, Professor Clive Osmond, Professor Jessica Teeling, and Dr Laurie Lau report no biomedical financial interests or potential conflicts of interest.

Hou R, Garner M, Holmes C, Osmond C, Teeling J, Lau L, Baldwin DS. Peripheral inflammatory cytokines and immune balance in Generalised Anxiety Disorder: Case-controlled study. Brain Behav Immun. 2017 May;62:212-218. doi: 10.1016/j.bbi.2017.01.021. Epub 2017 Feb 1. PMID: 28161475; PMCID: PMC5373436.