The psychiatric profession has finally come clean and confessed on a national media outlet that there is no evidence to support the Serotonin Theory of Depression. Today, on NPR’s Morning Edition there is a segment about the chemical imbalance theory, and virtually all the psychiatrists who are interviewed acknowledge that the there was never any evidence in support of the idea that low serotonin causes depression. But then, amazingly, they go on to say that it is perfectly fine to tell patients that serotonin imbalance causes depression even though they know this isn’t the case.

Several years ago in PLoS Medicine we wrote a long piece about the serotonin theory and the disconnect between what research psychiatrists say in professional journals and textbooks and what the advertisements say. While the advertisements presented the theory as scientific fact, the scientific sources clearly did not. Given the enormous marketing programs that pushed this theory combined with the media’s lack of skepticism, we were sympathetic to the general public who could hardly be faulted for thinking that theory had some foundation in fact. Following the publication of our piece a reporter contacted us and suggested that we were attacking a well accepted theory. We pointed out to the reporter that we weren’t attacking a sacred cow but that instead we were pointing out the mainstream psychiatry didn’t even accept this theory. We urged the reporter to contact the FDA, NIMH, APA, etc and ask them about the science behind the advertisements. He did, and as expected, an expert from the FDA explained that the theory was really just a metaphor. The problem is that patients who heard their physician explain the serotonin theory thought they were hearing real science. They weren’t told it was a metaphor and hence thought it was a fact. When a doctor talks about high cholesterol, diabetes, or hypothyroidism, they are talking about scientific measurement, not a metaphor. How is a patient with high cholesterol and depression who listens to their doctor’s explanation of their conditions supposed to know when the doctor has moved from science to metaphor?

Several months ago Ronald Pies published an interesting article in Psychiatric Times entitled, “Psychiatry’s New Brain-Mind and the Legend of the Chemical Imbalance.” Pies, just like the experts on NPR, acknowledges that the Chemical Imbalance theory is not true. However, according to Pies, it was the pharmaceutical companies who espoused the theory, and not well-informed, practicing clinicians, because the psychiatry community has known all along that the theory is not true.

But if the Psychiatry Community knew all along that the theory was not true, then why did they not clarify this issue for the general public? Shouldn’t they have pointed out to the general public and patients that what the pharmaceutical companies were saying about psychological stress was not true? Why did the professional societies not publicly set the record straight?

There are many angry comments on the NPR website. These comments are interesting, because apparently many patients who were told that depression is caused by a chemical imbalance never understood that were hearing a metaphor and not science. Since the chemical imbalance theory is often presented as a rationale for taking SSRIs, such patients now understandably feel lied to by their clinicians.

Perhaps the most interesting part about the NPR piece is that the reporter seems to not understand that the idea of telling a falsehood to patients because you think it is good for them is a serious violation of informed consent. Shouldn’t the reporter have asked the obvious questions, such as:

1) Do you feel it is acceptable to present a scientific theory as fact even though you know it is false?

2) Is it okay for psychiatrists to tell patients stories about their conditions that psychiatrists know are false?

3) Is there not an ethical issue when a psychiatrist informs their patient that they have a serotonin imbalance, when the medical textbooks on the shelf clearly say this is a falsified theory?

In general, we are fans of NPR, but hopefully the next news outlet that covers this topic will be more investigative in their approach.

Update: Is it true that neuroscientists discarded the serotonin theory long ago? See Part 2 of this blog post for more information…