A drug currently used to treat rheumatoid arthritis may offer a breakthrough for individuals suffering from difficult-to-treat depression, according to a new study. Researchers at the University of Bristol have, for the first time, investigated whether tocilizumab, an anti-inflammatory medication, can alleviate symptoms in patients who do not respond to standard antidepressant therapies.
Current depression treatments primarily target brain chemicals like serotonin, norepinephrine, and dopamine. However, approximately one in three patients find no relief from these conventional approaches. The study, involving 30 participants with moderate-to-severe depression, provides early evidence that tocilizumab may reduce depressive symptoms, combat fatigue and anxiety, and improve overall quality of life.
The research builds on findings that roughly a third of people with depression exhibit signs of inflammation in their blood, suggesting their condition could be linked to an overactive immune system. Other studies have pointed to higher levels of inflammatory proteins called cytokines, including interleukin 6 (IL-6), in depression.
Researchers wanted to see whether blocking the IL-6 pathway could improve symptoms in people with inflammation-related depression. The trial split participants into two groups: half received tocilizumab, and the rest a placebo. The findings suggest that those who received tocilizumab experienced greater improvements over time compared to those given a placebo.
Senior author Professor Golam Khandakar from the University of Bristol said: "This work represents an important milestone in the development of new treatments for depression, especially difficult-to-treat depression, which affects millions of people in the UK alone. This is one of the first randomised controlled trials to test immunotherapy for depression, the first to test IL-6R as the treatment target, and the first to use a targeted approach to select patients most likely to benefit, and to show that it works."
Lead author Dr Eimear Foley added: "Depression is estimated to affect around 10% to 20% of people worldwide during their lifetime, yet for many patients current treatments do not work well enough. Our study moves us closer to more tailored depression care, where treatments are chosen to better fit a person’s biology. This will help us to provide the right treatment to the right patients at the right time."
The next step will be to conduct a large-scale phase III randomised control trial that will provide definitive evidence to enable doctors to prescribe immunotherapy for depression. The study, titled 'Interleukin 6 as a treatment target for depression: a proof-of-concept randomised clinical trial', is published in the journal JAMA Psychiatry.
