Depression is more common among individuals with chronic physical illness than in the general population. New treatments for severe and chronic inflammatory conditions which inhibit tumour necrosis factor alpha (TNF-α), a pro-inflammatory cytokine, may be able to shed some light on the role of inflammatory mediators in depression. This systematic review and meta-analysis of randomised controlled trials determined the effects of TNF-α inhibitor therapy on depression and anxiety in people with chronic physical illness.
Seven databases were searched from inception to January 2014: AMED, Central, Cochrane Database of Systematic Reviews, CINAHL, Embase, MEDLINE, and PsycINFO. Articles were screened for inclusion independently by two reviewers. Data extraction and appraisal were conducted by one reviewer and checked by a second. Random-effects meta-analyses were performed.
Six randomised controlled trials (reported in seven articles) met eligibility criteria and were included in the final review. In total 2540 participants were enrolled across the trials, with participants presenting with rheumatoid arthritis (n=3 trials), psoriasis (n=2) or ankylosing spondylitis (n=1). Meta-analyses, using standardised mean differences, showed evidence of small reductions in depression (-0.24; 95% CI -0.33 to -0.14; p<0.001), and anxiety (-0.17; 95% CI -0.31 to -0.02; p=0.02).
TNF-α inhibitor therapy reduces depression in people with chronic disease though the effects are small. Whilst this is consistent with inflammation contributing to the development of depression, further studies investigating a more detailed timeline of changes in depression, inflammatory biomarkers and disease activity status are required.