The consistent link between depression and chronic low-grade inflammation has long attracted the attention of researchers. A recent meta-analysis has shown that treating inflammation can reduce depressive symptoms in two ways, offering a potential alternative to traditional antidepressants and their side effects.

The Connection Between Depression and Inflammation

Since the 1980s, it has been known that there is a certain relationship between depression and inflammatory processes. However, it remains unclear what is the cause and what is the effect: do people with chronic inflammation experience depression due to symptoms like pain, fatigue, and frequent colds, or does depression itself contribute to the development of inflammation in the body? Most importantly, can treating inflammation help alleviate depression?

New Research Findings

Earlier studies produced conflicting results. Now, most experts agree: if depressive symptoms are caused primarily by inflammation, then treating the inflammation can indeed be effective.

This hypothesis is supported by new research conducted at Brigham and Women's Hospital. The scientists noted that many previous studies were not precise enough, as they examined the use of anti-inflammatory drugs in a broad group of people with depression, rather than specifically in those suffering from both depression and chronic inflammation.

Meta-Analysis Results

The researchers conducted a meta-analysis that included 11 studies with 321 participants who had both confirmed chronic inflammation and depression, and who received anti-inflammatory medications. Despite the relatively small sample size, the results were promising.

"We found that anti-inflammatory drugs significantly reduced the severity of depressive symptoms and anhedonia by the end of the study," said lead author Naishi Mac Giollabhui. Anhedonia is a common symptom of depression, where a person loses the ability to experience pleasure.

The analysis yielded a Hedges’ g value of 0.4 for anhedonia—a standardized measure indicating how much better the treatment group felt compared to the placebo group. In practical terms, this means that if you randomly select one person from each group, the participant who received anti-inflammatory treatment would report symptom improvement in about 60% of cases. For overall depressive symptoms, the Hedges’ g value was 0.35.

Prospects and Limitations

While the study confirms that anti-inflammatory drugs can improve symptoms in people with depression and immune system disorders, the authors emphasize the need for further research. It is important to develop immune biomarkers that can more accurately identify who will benefit most from such treatment, as well as to create therapies that selectively target abnormal inflammatory physiology.

Currently, some of the most effective anti-inflammatory drugs have serious side effects, which limits their use in clinical practice.

The study was published in the American Journal of Psychiatry.