Is depression caused by an inflamed brain? A review of studies looking at inflammation and depression has found that a class of anti-inflammatory drugs can ease the condition’s symptoms.
Golam Khandaker at the University of Cambridge and his colleagues analysed 20 clinical studies assessing the effects of anti-cytokine drugs in people with chronic inflammatory conditions. These drugs block the effects of cytokines – proteins that control the actions of the immune system. Anti-cytokines can dampen down inflammation, and are used to treat rheumatoid arthritis.
Together, these trials involved over 5,000 volunteers, and provide significant evidence that anti-cytokine drugs can also improve the symptoms of depression, Khandaker’s team found. These drugs work about as well as commonly used antidepressants, they say.
The most commonly used anti-depressant drugs, known as SSRIs, act to increase levels of serotonin in the brain, to improve a person’s mood. But depression might not always be linked to a lack of serotonin, and SSRIs don’t work for everyone.
Recent research has found that around a third of people with depression appear to have higher levels of cytokines in their brains, while people with “overactive” immune systems seem more likely to develop depression. Khandaker’s team think that inflammation in the brain might be responsible for the fatigue experienced by people with depression.
The type of drugs Khandaker’s team looked at are not the same as commonly-used anti-inflammatory drugs like ibuprofen, and some can have severe side effects. These will need to be fully assessed before anti-cytokines are prescribed more widely as anti-depressant drugs.
But finding out if a person with depression also has inflammation before deciding on their treatment could be useful in future. “It’s becoming increasingly clear to us that inflammation plays a role in depression, at least for some individuals,” Khandaker said in a statement. “Now our review suggests that it may be possible to treat these individuals using some anti-inflammatory drugs.”
Journal reference: Molecular Psychiatry, DOI: 10.1038/mp.2016.167