Study revives debate over chemical imbalance theory of depression

Based on a systematic review of 17 medical studies, a recently published study paper raised questions and sparked debate about the chemical imbalance theory of depression. Although the study did not carry out additional research, after synthesizing and assessing the evidence in the main relevant areas, the authors conclude that the long-held theory is unproven.

Serotonin is a monoamine neurotransmitter, a chemical that regulates mood, sleep, appetite, and sexual desire. The chemical imbalance theory suggests that depression is caused by a drop in serotonin levels in the brain.

The article, published on July 20 in the review Molecular psychiatry by a multinational team of researchers, is entitled “The Serotonin Theory of Depression: A Systematic Review of the Evidence”. The article challenges the “chemical imbalance” theory that began in the 1960s, based on the premise that reduced serotonin activity causes depression. This hypothesis was derived from the fact that the first two specifically antidepressant drugs, discovered in the 1950s, were both shown to increase serotonin levels in the brain. Therefore, early experiments assumed a causal relationship between serotonin and depression.

Subsequently, a variety of antidepressants often referred to as “happy pills” were developed, promoted and reinforced this theory.

Although many professionals and the public still accept the serotonin theory of depression, the authors of the article said they found no conclusive evidence that depression is associated with or caused by reduced concentration. or serotonin activity in the brain. The study also calls into question whether boosting serotonin levels via antidepressants is a reliable treatment for depression.

Although clinical experts have determined that antidepressants help in the treatment of severe depression, their mechanism is not fully understood.

Response to study

The response from experts to the study was immediate and vigorous. On the day the newspaper was published, Britain Science Media Center published a roundup of various experts and their responses.

Among them was Michael Bloomfield, Ph.D., a psychiatrist and researcher at University College London. While Bloomfield said “the hypothesis that depression was caused by a chemical imbalance of serotonin was a really big step forward in the mid-20e century,” he called the review “unsurprising.” He noted, “I don’t think I’ve come across any serious scientists or psychiatrists who think that all causes of depression are caused by a simple chemical imbalance of serotonin.”

Phil Cowen, a professor of psychopharmacology at Oxford University, has studied the effects of serotonin on depressed patients for 30 years. He thinks “no mental health professional” today would support the idea that a complex disorder like depression stems from “a single neurotransmitter deficiency”.

Professor Gitte Moos Knudsen, head of the Department of Neurology and Neurobiology Research Unit at the Danish University Hospital in Copenhagen, said the study is based on a misconception that “depression is a single disease with a single biochemical deficit”. Today, Knudsen notes, “it is widely accepted that depression is a heterogeneous disorder with potentially multiple underlying causes.”

Rethinking how antidepressants work

Although the July 20 article does not focus on the pros and cons of using antidepressants, their mechanism of action in treating depression has become the focus of discussion. This is because most of the antidepressants used today have their roots in the dubious chemical imbalance theory.

In response to the study, Frederick Sundram, associate director of psychological medicine at the University of Auckland, New Zealand, wrote that the mechanism of action of antidepressants is not yet fully understood. He believes there may be other mechanisms at work, such as neuroplasticity. Moreover, he writes, 30 to 40% of the effectiveness of antidepressants is due to a placebo effect.

Sundram asserted that the brain chemical imbalance theory takes a simplified approach to a very complex human condition, an approach that is not shared by most psychiatrists. For example, he said, if someone has a history of personal trauma and lives under the constant stress of social isolation, unemployment, economic problems, leading to depression, it is unlikely that antidepressants solve the problem.

In March, the World Health Organization (WHO) published a report which reflects Sundram’s point of view. The report noted that the global prevalence of anxiety and depression increased by 25% in 2020, during the COVID-19 pandemic. The WHO said people’s anxiety and depression were exacerbated by feelings of isolation due to lockdown, financial worries and fear of illness or death for themselves and loved ones. All of these issues are where an antidepressant alone may be insufficient.

The Royal College of Psychiatrists, a UK mental health authority, responded to the study citing its position paper on antidepressants (pdf), which points out that while the idea of ​​using antidepressants “to correct a chemical imbalance in the brain” is too simplistic, they have early physiological and psychological effects.

The Royal College suggests that “antidepressants treat the symptoms of depression, but do not directly address the underlying psychosocial causes, so medication is often combined with psychotherapy which may improve the patient’s ability to cope. to difficult situations in life.

An Integrative Medicine Perspective

Dr. Jing-Duan Yang is a psychiatrist and founder of the Yang Institute of Integrative Medicine. In a video presentation on Aug. 20, Yang explained why the chemical imbalance theory has become so prevalent. Yang said once a theory developed by science is tied to a product, its promotion and subsequent researchers tend to exaggerate or embellish the original scientific evidence.

Based on his 20 years of clinical experience, Dr. Jing-Duan Yang believes that antidepressants work for some patients. However, “it remains to be seen whether [they work] the way it was originally assumed,” he said.

Dr. Yang thinks antidepressants have helped reduce inflammation in the brain, and some studies suggest that depression is linked to the inflammatory response in the brain. Therefore, these drugs may improve serotonin function, but through another mechanism.

Side effects of antidepressants should prompt caution

Yang said that although antidepressants are clinically proven and effective for many people, most have a variety of side effects, so patients should be careful when using them.

Yang gave the example of a patient he treated for almost twenty years. The patient has been using the common drug Cymbalta for about ten years to improve her serotonin and norepinephrine function for anxiety and depression. The patient reported side effects such as weight gain and increased blood pressure.

After switching the patient to Lexapro, a drug that simply improves serotonin function, her anxiety and depression improved again. But it didn’t take long for her to regain weight. She started having other disturbing side effects such as decreased libido, blurred vision and feeling like ants and insects were crawling on her body.

Yang said the most serious concern about this and other common antidepressants is their black box warning, which warns that adolescents and young adults are prone to more suicidal thoughts and tendencies in the first weeks of life. taking the drug. Also, in some people, antidepressants increase symptoms of depression.

Traditional Chinese medicine treats depression

Dr. Dong Shidao, a traditional Chinese medicine (TCM) physician living in New Zealand, told The Epoch Times that TCM believes depression is strongly linked to the liver and its response to human emotions.

Chinese medicine believes that the liver plays a key role in controlling the flow of Qi– usually translated as “vital energy” – through the body. When the liver is free from emotional turmoil, qi flows smoothly and depression is avoided. Depression occurs when negative emotions disrupt the functioning of the liver and the flow of qi becomes stagnant or blocked.

Dong believes that people become prone to liver qi stagnation when they allow worry and anxiety to go unchecked. Instead of learning to take care of themselves by developing support systems and good relationships, people today spend too much time on their cellphones and computers, Dong says. They don’t know how to calm their worries in a healthy way, in order to avoid liver-related depression.

Dong thinks “the stresses of modern society only make depression worse.” To make his point, he uses a famous Chinese saying: “If justice exists within, evil will not enter.” He predicts that the more society devolves, the more people will be vulnerable to depression.

“Chinese medicine also has drugs to treat liver qi stagnation,” Dong said. “But medications and acupuncture focus on unblocking and adjusting the whole body.” TCM frequently uses a botanical formulation called Xiao Chi Hu Tang. The seven-herb formula was developed 1,800 years ago in China by Dr. Zhang Zhongjing and is still used today to treat liver and gastrointestinal disorders.

Sharon D. Cole