Inflammation can interfere with the balance of neurotransmitters in the brain, making antidepressants less effective. Anti-inflammatory treatments (such as those used to treat rheumatoid arthritis) may help. In a 2016 meta-analysis published in the journal Molecular Psychiatry, researchers led by Nils Kappelmann analyzed the results of 20 clinical trials of chronic inflammatory conditions where depressive symptoms were also recorded. In a subset of 7 clinical trials that compared anti-inflammatory treatment to placebo, they found that anti-inflammatory treatment improved depressive symptoms significantly compared to placebo.
The anti-inflammatory drugs studied most often targeted the inflammatory marker tumor necrosis factor (TNF) alpha using an antibody. Some of the anti-inflammatory drugs that improved depressive symptoms were adalimumab, etanercept, infliximab, and tocilizumab.
The researchers also found that those participants with the most inflammation when they began treatment saw the largest improvement in their depression after taking anti-inflammatory treatments.
Kappelmann and colleagues suggest that inflammation may cause depression, and that anti-inflammatory drugs may be useful in the treatment of depression in people with high inflammation.