Serotonin and depression

In a recent review, Moncrieff et al (2022) note that the decades-long idea of depression being the result of a chemical imbalance in the brain – especially serotonin (5-hydroxytryptamine or 5-HT) – has justified the use of selective serotonin reuptake inhibitor antidepressants. It is an idea that has helped cement the view that mental health problems are largely explainable in the language of wayward brain chemistry. Indeed, one might infer that over many years the mind has become academically suspect, with the psychiatrist's couch consigned to the attic to make room for the CT scanner since it is clear that mental health problems are caused by apparently verifiable brain pathologies.

Despite this, Moncrieff et al (2022) have set a scientific cat amongst certain evidential pigeons by concluding that ‘[t]here is no convincing evidence that depression is associated with, or caused by, lower serotonin concentrations or activity.’ Some sharp responses have ensued. For example, the strapline to an article by Kendrick and Collinson (2022) not only asserts that antidepressants ‘remain an effective treatment for depression, even without the “chemical imbalance” explanation’, but the authors claim that the conclusions of Moncrieff et al (2022) ‘could encourage sudden antidepressant cessation, causing withdrawal symptoms and risking relapse.’