Reviews show no association between serotonin levels, chemical imbalances, and depression

There is no clear evidence that serotonin levels or serotonin activity are responsible for depression, according to a major review published in Molecular psychiatry.

Researchers at University College London (UCL) have conducted a comprehensive review covering decades of research on serotonin and depression. According to the authors, this finding suggests that depression is unlikely to be caused by a chemical imbalance, and is a conclusion that questions what antidepressants do to patients.

“Many people are taking antidepressants because they have been led to believe that depression is a biochemical cause, but this new study suggests that this belief is not evidence-based. “We are,” said Joanna Moncliffe, a psychiatrist and professor of psychiatry at UCL. Northeast London NHS Foundation Trust (NELFT) in a statement.

“The popularity of the’chemical imbalance’theory of depression is consistent with a significant increase in the use of antidepressants,” she added. “Antidepressant prescriptions have increased dramatically since the 1990s, with one in six adults and two percent of teenagers being prescribed antidepressants in a particular year in the UK.”

Most antidepressants are selective serotonin reuptake inhibitors (SSRIs). SSRIs were initially said to work by correcting abnormally low serotonin levels. Currently, there are no other accepted pharmacological mechanisms by which antidepressants affect the symptoms of depression.

This review aims to collect all relevant studies published in the field of serotonin and depression research. Cumulatively, the review study involved tens of thousands of participants.

Studies comparing the levels of serotonin and its degradation products in blood or brain fluid showed no difference between depressed individuals and control participants.

In addition, studies of serotonin receptors and serotonin transporters have found weak and inconsistent evidence suggesting high levels of serotonin activity in people with depression. Researchers say these findings are likely to be explained by the use of antidepressants among people diagnosed with depression.

Researchers also reviewed studies that artificially reduced serotonin levels in hundreds of people by depriving the diet of the amino acids needed to make serotonin. Many of these studies are said to have shown an association between serotonin deficiency and depression, but a meta-analysis conducted in 2007 and a sample of a recent study showed that this method lowered serotonin. It turns out that hundreds of healthy volunteers do not suffer from depression.

However, there was very weak evidence of association in a small subgroup of people with a family history of depression. Researchers noted that only 75 participants were involved in this subgroup, emphasizing that recent evidence was inconclusive.

This review included a large study examining genetic mutations in tens of thousands of patients. These studies included the gene for the serotonin transporter. No differences were found in these genes between depressed individuals and healthy controls.

Some of these studies have found that stressful life events have a strong impact on people’s risk of depression. One well-known early study found a link between stressful events, the type of serotonin transporter gene a person had, and the likelihood of depression. However, larger and more comprehensive studies are inconsistent with the finding and suggest that it was wrong.

“One of the interesting aspects of the study we examined was how strongly the depressive and harmful life events had an impact. This is because depression is a reaction to people’s lives and is simple. It suggests that it cannot be summarized in a chemical equation, “said Mark Horowitz of MBBS, PhD. In a press release, UCL and NELFT psychiatric training psychiatrists and clinical researchers.

Taken together, these findings led the authors to conclude that “the hypothesis that depression is caused by decreased activity or concentration of serotonin is not supported.”

“It’s always difficult to prove negative, but after decades of extensive research, convincing evidence that depression is caused by abnormalities in serotonin, especially low levels or decreased activity. I think we can safely say that there is no serotonin, “Moncliffe said in a statement.

Studies show that 85% to 90% of the general public believe that depression is due to a decrease in serotonin or a chemical imbalance, emphasizing the importance of these findings. According to the author, an increasing number of scientists and professional groups are aware of the framing of chemical imbalances as oversimplification.

In particular, the authors also found evidence in a large meta-analysis of low blood serotonin levels in people who used antidepressants. They concluded that some evidence is consistent with the potential for long-term antidepressant use to reduce serotonin levels. semester.

The researchers did not review the efficacy of antidepressants in this study. However, instead of antidepressant, the author further studies treatments that focus on managing stress and traumatic events in people’s lives, such as psychotherapy, along with other practices such as exercise and mindfulness. Is encouraging.

They also recommend addressing root causes such as poverty, stress and loneliness.

“In our view, depression should not be told to patients that it is caused by a decrease in serotonin or chemical imbalances, and it is believed that antidepressants work by targeting these unproven abnormalities. We shouldn’t let people know exactly what antidepressants are doing to the brain, and if we give people this kind of false information about whether to take antidepressants You will not be able to make informed decisions, “Moncliffe concludes.

Horowitz said: It’s amazing to be involved in this research, and it feels like everything I thought I knew was upside down. “

Researchers have questioned the effectiveness of antidepressants, but those considering quitting antidepressants warn them to consult a health care professional, considering the negative effects of withdrawal. I am.

“Thousands of people suffer from the side effects of antidepressants, which include severe withdrawal symptoms that can occur when people try to stop antidepressants, but prescription rates increase. We believe that this situation was partly caused by a false belief that depression was due to a chemical imbalance. To the public that this belief is not based on science. It’s time to let them know, “the authors write.

Moncrieff and Horowitz are conducting ongoing research on the best way to gradually stop taking antidepressants.

reference

There is no evidence that depression is caused by low serotonin levels, find a comprehensive review. Eurek Alert. news release. July 19, 2022. Accessed on July 20, 2022. https://www.eurekalert.org/news-releases/959220