One of the world’s largest drug makers is testing a new approach to treating depression — by dialing down inflammation in the body, rather than adjusting chemicals in the brain.

If it works, it could also open the door to a new field of drug development for other psychiatric conditions, including bipolar disorder, anxiety disorders, and schizophrenia, all of which are tied, in part, to immune activity in the brain, the Boston Globe reports.

“The notion that you can block inflammation and relieve some of the symptoms of depression is really just the tip of the iceberg,” said Dr. Andrew Miller, a psychiatrist at Emory University.

The new trial is being run by Johnson & Johnson, which started enrolling patients with depression at sites in Russia, Poland, Canada, and the United States. The company is testing an experimental drug called sirukumab, which blocks a key inflammatory protein called interleukin 6.

For years, depression was believed to be tied to an imbalance of brain chemicals, and antidepressants work by tweaking them. But nearly one in three of the estimated 35 million Americans who use those drugs aren’t helped by them.

New research suggest inflammation can also cause mental illness, so treating it with anti-inflammatories might prove useful.

“As recently as 2000, this was considered a fringe area of science, viewed with considerable skepticism,” said Dr. Wayne Drevets, a psychiatrist who leads mood disease research at J&J. “It is now mainstream thinking in biological psychiatry.”