A meta-analysis of 17 studies shows that there is no link between depression and serotonin levels. This calls into question certain widely prescribed treatments such as selective serotonin reuptake inhibitors (SSRIs).
Serotonin is a molecule produced by neurons to modulate communication between other neurons in our brain. Its functions are numerous but this neuromodulator would be particularly involved in the regulation of mood and anxiety. This explains why, since the beginning of the 1990s, treatments known as selective serotonin reuptake inhibitors (Prozac, Zoloft, Deroxat, Seropram, etc.) have been the most prescribed antidepressants.
But a meta-analysis of 17 studies, carried out by researchers from the University College of London (Great Britain) led by psychiatrist Joanna Moncrieff, calls into question the role of serotonin in depression (and therefore the effect of SSRIs).
The effectiveness of SSRIs is due to the placebo effect
After analyzing these studies involving several hundred thousand patients, the researchers found that there was no evidence that low serotonin activity or levels caused depression. “The idea that depression is the result of abnormalities in brain chemicals, particularly serotonin (5-hydroxytryptamine or 5-HT), has been influential for decades and provides important rationale for the use of antidepressants. However, what our study implies is that we don’t know what SSRI antidepressants do“, explains Professor Moncrieff. “One possibility would be that they work through the placebo effect”, adds the psychiatrist.
This study obviously caused a stir among psychiatrists, and in particular the Royal College of Psychiatrists, who urge patients not to stop their treatment: “Antidepressants have variable effectiveness depending on the person, and the reasons for this are complex. We encourage anyone with concerns about their medication to contact their doctor.
Source : The serotonin theory of depression: a systematic umbrella review of the evidenceMolecular psychiatry, July 2022
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