Depression may not be caused by a chemical imbalance according to new study

by Trinity Cardinal

Lauren Dempsey, MS in Biomedicine and Law, RN, FISM News 

  

The ancient Greeks called what we now know as clinical depression, melancholia. Regardless of the name, the mental illness presents as a persistent feeling of sadness, low self-esteem, loss of interest in activities that are normally enjoyable, and can impact a person’s ability to eat, sleep, and function in daily life.

In the 1960s it was theorized that depression was caused by a chemical imbalance in the brain that could be addressed by taking antidepressants. This theory has long been accepted by the medical community and further backed by big pharma.  

However, a new review from the University College London (UCL) suggests that the science no longer supports this theory which has become scientific dogma in the fields of psychiatry and psychology. The authors argue that while the idea of a chemical imbalance has been “an important justification for the use of antidepressants,” there is no clear evidence that supports the theory that low serotonin is the cause of depression. 

The researchers conducted an umbrella review that included existing systematic reviews, meta-analyses, individual studies, and one genetic study. They discovered that there is strong evidence that suggests that stressful life events are more likely to be the cause of depression. Some of the studies indicate that antidepressants, especially selective serotonin reuptake inhibitors (SSRI), lower the function and availability of serotonin in the brain. 

Co-author Dr. Mark Horowitz, a training psychiatrist and Clinical Research Fellow in Psychiatry at UCL and North East London NHS Foundation Trust (NELFT), commented that this study has been “eye-opening” and that, what he thought he knew about depression and treatment of the disorder, had been “flipped upside down.”

“One interesting aspect in the studies we examined was how strong an effect adverse life events played in depression, suggesting low mood is a response to people’s lives and cannot be boiled down to a simple chemical equation,” Horowitz said.

Researchers found in studies that compared levels of serotonin and its breakdown products in the blood or brain fluids, that there was no difference between people diagnosed with depression and healthy control participants. When evaluating studies on serotonin receptors and the serotonin transporter, which is the protein targeted by most antidepressants, researchers found the evidence was lacking to prove there were higher levels of serotonin activity in people with depression.

Based on their review, the authors of this study recommend that physicians should no longer tell patients that antidepressants will treat depression by fixing a chemical imbalance, citing a limited understanding of what antidepressants actually do to the brain.

Surveys show that more than 80% of the general public believe that it is well established in scientific evidence that depression is caused by a chemical imbalance. Depression affects more than 21 million Americans, including 15% of individuals aged 12-17. It is estimated that only about one-third of those with depression seek help. 

Professor Joanna Moncrieff, the lead author of the study and a Professor of Psychiatry at UCL and a consultant psychiatrist at NELFT, urged the importance of informing the public about these findings.

“Thousands of people suffer from side effects of antidepressants, including the severe withdrawal effects that can occur when people try to stop them, yet prescription rates continue to rise,” Moncrieff said. She also stresses that patients should be aware that their treatment for depression is based on a hypothesis. 

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