Irish psychiatry says chemical imbalance is ‘a figure of speech,’ so – what now?


The chemical imbalance theory of depression – what was once considered the gold standard reason for why people take antidepressants, was, apparently, ‘a figure of speech’.

This gobsmacking admission from The College of Psychiatrists of Ireland appeared on its website in what seems to be relatively new content to reflect the long-known reality – there is not, or has never been any scientific evidence to support the chemical imbalance theory.

Most people reading the Mad in Ireland website will have known for quite some time that the chemical imbalance theory was debunked. The reason we say ‘gobsmacking’ is because it’s not something that Irish psychiatrists have said publicly before, although a representative for the College did say in a 2015 media article that people didn’t really believe it anyway.

This is simply not the case. Any wonder, when for decades, people have been deluged with information suggesting that depression is caused by a “chemical imbalance” in the brain – for example, an imbalance of a brain chemical called serotonin. 

A survey indicates that actually more than 80% of the public blame a “chemical imbalance” in the brain for depression, so clearly it’s not enough to quietly retract something that’s been held up as the cause of depression, by simply saying, it was a figure of speech.

The ‘figure of speech’ phrase in itself is interesting. The chemical imbalance theory has in recent times been called things like a careless metaphor rather than the concrete fact it was communicated as for many years – see for example see Harvard Health.  There are many other sites including the phrase or something similar, an attempt, perhaps, to rewrite history, now that the theory has been debunked.

According to well-known researcher and psychiatrist Professor Joanna Moncrieff:

“In the 1980s, when the first SSRI, Prozac, was launched, “the pharmaceutical industry knew it couldn’t market them in the same way (as benzos) because numbing someone’s unhappiness had got a bad rep with the benzodiazepines…So, it had to convince people that they had an underlying disease and needed to take the drugs for an underlying disease.”

Moncrieff has been instrumental in bringing to light the issues associated with psychiatric drugs and in stating why it’s so important that people know the truth. She says whether antidepressants work or not depends on how we ‘understand what they are doing.’ And if they are not correcting a serotonin imbalance, or reversing some underlying mechanism of depression, “what are they doing?”

​​When people are taking mind-altering drugs that they believe corrects a chemical imbalance, you’d imagine it would be a priority to tell them if the science changes, or thinking shifts.

Why does this matter? 

This matters because research shows that people who have biological explanations for mental illness tend to be stigmatised and this belief can leave people feeling pessimistic about their chances of recovery. 

A study, published in the Journal of Affective Disorders, found patients who believe that a chemical imbalance in the brain causes depression to have worse treatment outcomes. 

The results of the study, which included a sample of 279 persons attending an intensive behavioral health program in the United States, found that the endorsement of the chemical imbalance theory of depression was associated with poorer expectations of treatment and lower perceived credibility. Additionally, the researchers found that a belief in biological causes for depression was predictive of a greater presence of depressive symptoms at the end of treatment. Schroder and his colleagues write:

It matters because the media, and even many people who work in mental health continue to believe in the chemical imbalance theory of depression. This makes it hard for the media to challenge the mainstream narrative around a biomedical approach to mental health and it makes a culture shift within mental health itself harder to achieve.

It’s more clear than even that prescribers need to talk honestly with patients, explaining that it is unclear how antidepressants ‘work’, even for ‘depression’, and that serotonin, etc. has multiple effects — on all physiological systems as well as on feelings of overwhelm, hopelessness, and ‘depression’. These effects can include paradoxical suicidality, sexual dysfunction, blunted emotions, digestive problems, fatigue, weird dreams, and compulsions — among other side effects that affect mood.

What are the drugs doing?

The World Health Organization (WHO) guidelines on depression treatment are clear: “Antidepressant medications are not needed for mild depression.” 

Multiple studies have found that even for severe depression, adding antidepressants to cognitive behavioral therapy does not result in better outcomes—psychotherapy alone is just as good in the short term. And therapy alone beats the drugs when it comes to long-term outcomes.

Prof Moncrieff has written several excellent papers outlining what she calls the drug-centred model of drug action. 

She argues that…“Unlike the current disease-centred model, which suggests that psychiatric drugs work by correcting an underlying brain abnormality, the drug-centred model emphasises how psychiatric drugs affect mental states and behaviour by modifying normal brain processes. The alterations produced may impact on the emotional and behavioural problems that constitute the symptoms of mental disorders.” (See Table 1)

In other words, just like any other drug, psychiatric drugs have mind- and behaviour-altering properties. 


As it becomes more apparent that the medical model needs to change but that vested interests are very reluctant to be open and honest about how and why it needs to change, professional activism is becoming more commonplace- and important.

Published in the British Medical Journal (BMJ), 30+ prominent figures called on the UK government to acknowledge the evidence that antidepressants are no better than placebos for most patients and to increase funding of social and psychological interventions while decreasing drug prescriptions.

“Multiple meta-analyses have shown antidepressants to have no clinically meaningful benefit beyond placebo for all patients but those with the most severe depression,” they said.

“Our findings are in line with accumulating evidence that some biogenetic beliefs, like the chemical imbalance belief, are linked with poorer expectations for improvement, especially among those with the most troubling symptoms.”

As reported by Mad in Ireland last year, there is also advice in the UK around tapering, with pharmacists in England being urged to assist people who want to stop antidepressants.

Honest conversation needed

Given all of this, it really is long past time for an honest debate in Ireland around these issues. While in the past there has been backlash for professionals seen not to be towing certain lines, surely with all of the research and information out there, this concern doesn’t apply anymore? 

Some immediate questions arise from the CPI’s admission that the chemical imbalance theory of depression was just ‘a figure of speech,’ namely:

Has the concept been removed from training materials and replaced with all of the new science and studies around antidepressants and other psychiatric drugs?

Is there a programme of work to inform various sectors such as social workers, pharmacists and GPs as a starting point. 

GPs in particular should be given uptodate information ensuring that informed consent is always the goal. Media should be informed and a public service campaign should be considered. For example, in other areas of health promotion good information e.g. FAST in relation to stroke is important to have in the public domain.

If the chemical imbalance theory is still what a large swathe of the public believe -don’t researchers, mental health practitioners and people who are responsible for mental health policies have an ethical responsibility to ensure that the public has the most up-to-date and evidence-based facts? This news might be upsetting for people, but it’s morally wrong not to tell them.

Only then can informed consent about medication become a reality rather than an abstract theoretical ‘figure of speech.’

To continue this important conversation we are interested to hear from people who would like to share their experiences of distress and healing in ways beyond  the current dominant  ‘figure of speeches’.