The widely held belief that depression is due to low levels of serotonin in the brain — and that effective treatments raise these levels — is little more than a big lie, argues a leading psychiatrist in the British Medical Journal.

David Healy, M.D., a professor of psychiatry at the Hergest psychiatric unit in North Wales, says it is a misconception that lowered serotonin levels are at the root of depression and that arguments suggesting a link amount to "the marketing of a myth."

His claims raise new questions about the use of serotonin reuptake inhibiting (SSRI) drugs, a popular class of antidepressants used since the late 1980s, Medical Xpress reports.

Drug companies market SSRIs for depression, "even though they were weaker than older tricyclic antidepressants, and sold the idea that depression was the deeper illness behind the superficial manifestations of anxiety," Dr. Healy explains. The approach was very successful — "central to which was the notion that SSRIs restored serotonin levels to normal, a notion that later transmuted into the idea that they remedied a chemical imbalance."

He argues there is no evidence that SSRI treatment corrected anything.

"For doctors it provided an easy short hand for communication with patients,” he writes. “For patients, the idea of correcting an abnormality has a moral force that can be expected to overcome the scruples some might have had about taking a tranquillizer, especially when packaged in the appealing form that distress is not a weakness."

Meanwhile more effective and less costly treatments were marginalized, he says.