Serotonin: How Psychiatry Got Over its `High School Crush’

“We’ve had six or seven decades with this paradigm, what I call the “high school crush” on serotonin.”—Dr. Roger McIntyre1

I owe the cheeky title of this piece to Roger McIntyre, MD, professor of psychiatry and pharmacology at the University of Toronto, who was interviewed at the recent APA meeting in Toronto. But before providing some context for Dr. McIntyre’s quip, I would invite you to consider two claims relating to mental illness:

1. Psychiatrists think most mental illnesses are caused by a “chemical imbalance.”

2. Psychiatrists think that some mood disorders are associated with abnormal serotonergic neurotransmission, among other functional or structural brain abnormalities, which may or may not be the “cause” of the disorder.

Because there are light years of conceptual space between these two claims, you might imagine, or naively hope, that psychiatry’s most strident critics would be able to distinguish claim 1 from claim 2.

Alas, anti-psychiatry bloggers continue to bang away at the notion that “Psychiatry” (that sinister, monolithic corporate entity) deliberately duped the public by promoting a bogus “chemical imbalance theory,” in cahoots with “Big Pharma.”

Suffice it to say that this line of argumentation is itself bogus, for reasons I have reiterated at length in several venues.2,3

For example, in 2005, on a publicly available website, the American Psychiatric Association clearly stated, “The exact causes of mental disorders are unknown…[but] we can say that certain inherited dispositions interact with triggering environmental factors.”4

At that time (2005), the same APA website also indicated that “several factors can play a role in the onset of depression,” including “biochemistry” (abnormalities in brain chemicals or brain networks), genetics, personality and environmental factors.

`Chemical Imbalance Theory’

To my knowledge, no professional psychiatric organization has ever publicly promoted a “chemical imbalance theory” of mental illness in general. (And, no—the original biogenic amine hypothesis was not a “theory”—the scientific distinction is important).5

That anti-psychiatry bloggers assiduously comb the Internet and find a handful of “celebrity psychiatrist” quotes to the contrary neither surprises nor impresses me.

But there is a sense in which some of psychiatry’s critics have a point and this brings us back to Dr. McIntyre and our old friend (or “frenemy?”), serotonin.

It was not difficult for the general public—and alas, some doctors—to pick up the skein of serotonin and weave an entire tapestry with it, ultimately producing the threadbare “chemical imbalance theory.”

No doubt, this was abetted by drug company “illustrations” of serotonergic synapses, complete with little packets of neurotransmitters whose re-uptake is inhibited by the company’s ace antidepressant.6

Even today, some non-pharma websites continue to post misleading diagrams that attribute depression to a “chemical imbalance,” as Dr. John Grohol recently discovered.7

So, to be clear: in order to establish, for a particular patient, a bona fide “imbalance” of neurotransmitters, we would need a “God’s-eye view,” in real time, of the dozens (hundreds?) of neurotransmitters in her brain; their relative concentrations in relation to well-validated norms; and their deviations from the patient’s normal baseline.

Serotonin: How Psychiatry Got Over its `High School Crush’

This article originally appeared in:

Psychiatric Times

It is reprinted here with permission.

Ronald Pies, MD

Dr. Pies is Professor Emeritus of Psychiatry and Lecturer on Bioethics and Humanities, SUNY Upstate Medical University; Clinical Professor of Psychiatry, Tufts University School of Medicine; and Editor-in-Chief Emeritus of Psychiatric Times (2007-2010).


APA Reference
Pies, R. (2015). Serotonin: How Psychiatry Got Over its `High School Crush’. Psych Central. Retrieved on August 13, 2020, from


Scientifically Reviewed
Last updated: 22 Sep 2015
Last reviewed: By John M. Grohol, Psy.D. on 22 Sep 2015
Published on All rights reserved.