The widely held belief that depression is due to low levels of serotonin in the brain - and that effective treatments raise these levels - is a myth, according to a leading UK psychiatrist.
David Healy, Professor of Psychiatry at the Hergest psychiatric unit in North Wales, points to a misconception that lowered serotonin levels in depression are an established fact, which he described as "the marketing of a myth."
The serotonin reuptake inhibiting (SSRI) group of drugs came on stream in the late 1980s, nearly two decades after first being mooted, Healy wrote in the British Medical Journal (BMJ).
After concerns emerged about tranquilliser dependence in the early 1980s, drug companies marketed 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," he said.
The approach was an astonishing success, "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," said Healy.
"In the 1990s, no one knew if SSRIs raised or lowered serotonin levels, they still don't know. There was no evidence that treatment corrected anything," he noted.
Healy suggested that the myth "co-opted" many, including the complementary health market, psychologists, and journals. But above all the myth co-opted doctors and patients, he said.
"For doctors it provided an easy short hand for communication with patients. 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 tranquilliser, especially when packaged in the appealing form that distress is not a weakness," said Healy.
Meanwhile more effective and less costly treatments were marginalised, he said.
Healy stressed that serotonin "is not irrelevant" but this history "raises a question about the weight doctors and others put on biological and epidemiological plausibility.
