Nuances, Narratives, and the 'Chemical Imbalance' Debate in Psychiatry

Ronald W. Pies, MD


April 15, 2014

In This Article

Debunking an Urban Legend

In fact, in the same year as the APA statement, Drs. Thomas Insel and Remi Quirion wrote a seminal article[3] proposing that "...mental disorders need to be addressed as disorders of distributed brain systems with symptoms forged by developmental and social experiences...." They went on to consider how "...environmental factors during critical intervals of development exert long-term effects on gene expression..." and suggested that "...studying unconscious processes, motivation, or defenses, while at one time the sole province of psychoanalytic therapies, are now also in the domain of cognitive neuroscience."

Does this sound like a simplistic chemical imbalance hypothesis? I don't think so. But then, why do antipsychiatry groups and bloggers fail to note the nuances of what psychiatrists have been saying for at least the past decade? My guess is that doing so would undermine the derogatory narrative they wish to promote. And, of course, nuanced statements do not gin up public opinion or sell books.

OK -- but weren't there many psychiatrists, in the 1980s and 1990s, who did advocate a purely biochemical theory of mental illness, often using the metaphor of the chemical imbalance to explain mental disorders to their patients? It's difficult to answer this question, except in an anecdotal way, but it's probably true that some psychiatrists did hold a purely biocentric view; and, alas, some undoubtedly used the expression "chemical imbalance" in their clinical practice, without putting it into a broader context for their patients.

It's also true, as critics of the chemical imbalance hypothesis point out, that the term "imbalance" is misleading. In order to validate an imbalance, we must first have a quantitative understanding of the optimal neurochemical balance in the brain -- and, given the scores of neurotransmitters now identified, this balance has yet to be ascertained. That said, I am not aware of any concerted effort by academic psychiatrists, psychiatric textbooks, or official psychiatric organizations to promote a simplistic chemical imbalance hypothesis of mental illness. That is what I meant when, in a 2011 Psychiatric Times piece, I referred to the chemical imbalance hypothesis as an "urban legend."[4]

But still, shouldn't psychiatrists in positions of influence have made greater efforts to knock down the chemical imbalance hypothesis, and to present a more sophisticated understanding of mental illness to the general public? Probably so. There were sincere attempts to do just that, by several prominent psychiatrists -- beginning nearly 50 years ago, with the developers of the catecholamine hypothesis. As psychiatrist Joseph Schildkraut and neuroscientist Seymour Kety wrote in 1967[5]:

Whereas specific genetic factors may be of importance in the etiology of some, and possibly all, depressions, it is equally conceivable that early experiences of the infant or child may cause enduring biochemical changes, and that these may predispose some individuals to depressions in adulthood. It is not likely that changes in the metabolism of the biogenic amines alone will account for the complex phenomena of normal or pathological affect.

Note the nuanced view of causality in this formulation -- allowing for the possibility that chemical changes in the brain are effects of early experience, but also predisposing factors in some subsequent depressive episodes. Note that Schildkraut and Kety did not argue that "chemical imbalances" per se cause depression.

To the extent the "chemical imbalance" notion took hold in our popular culture, it was due mainly to distorted or oversimplified versions of the catecholamine hypothesis. These were often depicted in drug company ads; pop psychology magazines; and, in recent years, on misinformed Websites and blogs. In short, the "chemical imbalance theory" was never a real theory, nor was it widely propounded by responsible practitioners in the field of psychiatry.


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