IN PERSPECTIVE
To date, no research has validated the chemical imbalance hypothesis with certainty, nor has it been possible to demonstrate that psychiatric drugs “correct” such an imbalance in the brain.
The hypothesis of
chemical imbalance
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Since its inception, psychiatry has sought to determine the origin of what it defines as “mental disorders”, proposing different explanations or hypotheses to explain them. Among these hypotheses, several attributed a major role to biology, to the body or to the brain.
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This is the case with the chemical imbalance hypothesis, which has been widely talked about since the 1960s. This hypothesis suggests that certain states classified as disorders by psychiatry are the manifestation of chemical imbalances in the brain. Since then, several studies have focused on one substance in particular: neurotransmitters.
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An example of the chemical imbalance theory explains that depression results from a lack of serotonin. Similarly, some psychiatrists have postulated in the past that schizophrenia is due to an imbalance in the amount of dopamine in the brain.
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It is mainly on this theory that the use of psychiatric drugs is based: the drug would come to correct the lack or the surplus of a chemical substance in the brain. For example, in the case of depression, biochemical theory suggests that antidepressants “correct” or “rebalance” serotonin levels. This would allow a better functioning of the brain and, therefore, of the person.
To date, however, no research has validated the chemical imbalance hypothesis with certainty, nor has it been possible to demonstrate that psychotropic drugs “correct” such an imbalance in the brain. This is also why there is no “objective” test (blood test, genetics, medical imaging, etc.) for mental health diagnoses.
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Models of the mode of action of psychiatric drugs
Psychiatric drugs are often presented as correcting the lack or excess of a chemical substance in the brain. For example, in the case of depression, biochemical theory suggests that antidepressants might "correct" or "rebalance" serotonin levels. This would allow a better functioning of the brain and, therefore, of the person.
This way of understanding the use of drugs corresponds to what Joanna Moncrieff calls the “disease-based model”. In this type of explanation, it is suggested that the drug comes to correct what would cause the “disease”, as does insulin for diabetes.
Yet, since there is no evidence for a biological basis for diagnoses in mental health, Joanna Moncrieff suggests understanding drug effects in terms of a model she calls the drug-based model. According to this model, the drug does not work because it would act on a "disease", but rather because it modifies the functioning of the brain in general, a little like alcohol does.
Indeed, alcohol is used by some to deal with social anxiety. Yet alcohol does not have a specific "social anxiety" target in the brain. We wouldn't say that alcohol is a medicine to cure anxiety. Despite this, it alters the functioning of the body and the brain as a whole, and it is this alteration that can help some people with social anxiety. See the table below for more on the drug based model.
The video below has Will Hall presenting a similar discussion on psychiatric drugs.
The table below presents Joanna Moncrieff's Drug Centred Model of psychiatric drug action, as opposed to the more common Disease Centred Model. This information was taken from her website.​​​​​
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Models of Drug Action
DISEASE CENTRED MODEL DRUG CENTRED MODEL
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Drugs help correct an abnormal brain state Drugs create an abnormal brain state
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Drugs as disease treatments Psychiatric drugs as psychoactive drugs
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Therapeutic effects of drugs derived from Therapeutic effects derive from the impact
their effects on an underlying disease process of the drug induced state on behavioural and emotional problems
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Paradigm: insulin for diabetes Paradigm: alcohol for social anxiety​​​​​​​​​​​
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