There is no link between depression and chemical imbalances in the brain, finding a major analysis

A review of 17 previous studies found no evidence of an association between depression and low serotonin levels, which SSRI antidepressants focus on, but everyone is convinced by the findings. It does not mean.

To Sara Wild

With serotonin levels depression, According to an analysis of 17 studies. This raises questions about antidepressants that focus on this brain signaling molecule, the authors of the analysis say. However, not everyone is convinced by the findings.

The serotonin hypothesis, dating back to the 1960s, states that a chemical imbalance in the brain containing low levels of serotonin, also known as 5-hydroxytryptamine or 5-HT, leads to depression. Currently, we believe that various biological, psychological, and environmental factors play a role, but the most popular antidepressant, known as a selective serotonin reuptake inhibitor (SSRI), is in the brain. Increases the availability of serotonin.

now, Joanna Moncliffe University College London and her colleagues conducted an “umbrella analysis” of 17 systematic reviews and studies. This included hundreds of thousands of people with and without depression.

Because it is difficult to directly measure real-time serotonin levels in the brain, 17 studies looked at serotonin depression and proximates, including molecules in the cerebrospinal fluid where serotonin is degraded. Levels of serotonin receptors and how active they are. Or, do people with depression have more genes for the serotonin transporter that removes serotonin?

Moncrieff’s team found that low activity or low levels of serotonin had no evidence of causing depression.

“The meaning of our treatise is that we don’t know what. [SSRI] Antidepressants are working, “says Moncrieff. One possibility is that they work through the placebo effect, she says.

but, Johann Landberg At the Karolinska Institute in Sweden, the limits of the analysis are those with ongoing depression and episodes of depression whose condition at the time of evaluation can affect the functioning of the serotonin system. I didn’t distinguish between people who are. “It’s important to analyze data from studies that look at the same patient when they’re sick and when they’re in remission, and set the optimal conditions for investigating the hypothesis,” he says.

According to Moncliffe, this review relied on studies already undertaken and did not highlight the difference between those who are experiencing symptoms of depression or those who have a history of depression.

“We must be aware that 5-HT is likely to be the only cause of depression,” he says. Paul Albert At the University of Ottawa, Canada. “Given the large placebo effect in the treatment of depression, the contribution of other systems, including dopamine, involved in the placebo effect may be greater than the contribution of 5-HT.”

“Antidepressants are an effective treatment for depression and are recommended by NICE and can be prescribed for a variety of physical and mental health conditions,” said a spokeswoman for the National Institute for Health and Care Technology. Said to the UK Science Media Center with reference to the following treatment guidelines: National Institute for Health and Care Technology (NICE). “Effects of antidepressants vary from person to person, but the reasons are complex. We do not recommend stopping antidepressants based on this review. Also, if you are concerned about your medication, your medication It is recommended to contact. [family doctor].. “

Journal reference: Molecular psychiatry, DOI: 10.1038 / s41380-022-01661-0

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