(NewsNation) — A stunning new study out of the United Kingdom suggests the neurological disorder depression is not actually caused by a chemical imbalance in the brain, going against decades of thought in the psychiatric world.

Dr. Joanna Moncrieff authored the study, which maintains there is “no evidence” depression is caused by a chemical imbalance. Rather, it holds, medical science actually has no clue what causes depression in humans.

“The theory that we had that depression was related to low serotonin levels, which was the basis of the development of modern anti-depressants, turns out not to be supported by evidence,” Moncrieff said.

Moncrieff said that many of the 37 million Americans who take anti-depressants to treat depression are likely feeling progress as a result of the placebo effect. She added, however, it is important that patients not stop taking their medication.

Moncrieff’s full interview on NewsNation “Prime” can be viewed above.