New study questions the link between depression and serotonin

A new study indicating that antidepressants are ineffective in treating depression has sparked widespread controversy in the scientific community.

The findings of the study demonstrate the difficulties in reaching an accurate and certain understanding of mental health disorders.

Currently, one of the prevailing theories regarding mental health focuses on serotonin, and links its deficiency with depression, as this substance helps transmit sensations to the brain.

The researchers’ findings indicating that depression is unrelated to a chemical imbalance in the brain due to a lack of serotonin, which negates the need for antidepressant drugs, have triggered outrage in the scientific community.

A study conducted by psychiatrists Mark Horowitz and Joanna Moncrieff and published in the journal Molecular Psychiatry last July found that there is no scientifically proven link between serotonin deficiency and depression.


The authors said that their findings questioned the basic theory behind the use of antidepressants, which were developed to modify serotonin levels, and toppled a theory that formed the basis for decades of research work.

The study based on several of previous scientific articles, quickly drew wide criticism, the most prominent of which revolved around the authors, as Dr. Joanna Moncrieff is known for her skepticism of biological explanations for depression and her extremist stance against the pharmaceutical sector.

“I generally support the authors’ conclusions about our current efforts, but I’m not with their assertive position on the matter,” psychiatrist Phil Quinn wrote on the Science Media Center website.

“No mental health professional can support the theory that a synaptic disorder such as depression results from a deficiency in a single neurotransmitter,” Quinn explained.

Mainstream psychological theories

Some psychiatrists have questioned the methodology used in the study, which is based on measuring serotonin indirectly rather than directly.

For her part, Moncrieff, who strives to change the so-called “mainstream psychological theories”, said that the theory about serotonin still occupies an important place in psychiatry, but the focus on it has diminished.

“Even if the most prominent psychiatrists began to question the evidence indicating that depression is associated with low levels of serotonin, none of them publicly addressed the issue,” Moncrieff wrote on her blog.

The link between depression and serotonin is deeply rooted in the public imagination. 

In 2019, the French writer “Michel Houellebecq” named the main character suffering from depression in his novel the name “serotonin”.

Moncrieff’s findings, which destroy the serotonin theory, question the efficacy of current antidepressants, bypassing the conclusions of her study and drawing harsh criticism.

Swiss psychiatrist Michele Hoffmann said the results of the Moncrieff study were “important” and helped spark discussions among experts about depression.

“I don’t think the study will make any difference in the short term to prescribing antidepressants,” she added.

Moncrieff cautioned that patients should not abruptly stop treatment with antidepressants, but pointed out that the benefits of taking these drugs would be questionable if they were based on a theory that lacked credibility.

The effectiveness of antidepressant treatments

However, many specialists stand by the effectiveness of treatment with antidepressants, which has been scientifically proven, regardless of the main cause of depression.

Doctor Hoffmann pointed out that usually several drugs are prescribed to treat depression and in the end in most cases we do not know what made the treatment effective.

The controversy surrounding the role of serotonin highlights the difficulty of understanding how a complex illness such as depression interacts biologically and socially, and the challenges are pushing researchers away from models that are incomplete in nature.

“We’re still just in the theories stage and we keep looking for models, testing them, and confronting each other with them,” Hoffman said.

Al Jundi

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