Depression not linked to a lack of serotonin, study finds

For over 60 years, many doctors and scientists have believed that there is probably a link between serotonin and depression. For this reason, many antidepressants focus on this hormone. Yet, it could ultimately be that depression is unrelated to serotonin.

The Serotonin Theory for Depression

Serotonin is a chemical produced by nerve cells. It is notably a hormone, and a neurotransmitter that sends signals between nerve cells. Although it is made by the brain, serotonin is mainly found in the digestive system. But it is also found in blood platelets and throughout the central nervous system. As a neurotransmitter, serotonin’s role is to help relay messages from one area of ​​the brain to another.

Due to the wide distribution of its cells, it is believed to influence a variety of physiological, psychological and other functions of the body. Physiologically, serotonin can affect the functioning of the cardiovascular system, muscles and various elements of the endocrine system. Psychologically, it influences brain cells related to mood, sexual function, appetite, sleep, memory, learning, temperature regulation, and certain social behaviors.

For this reason, there is a theory that links serotonin to depression. The serotonin hypothesis for depression posits in particular that a reduction in serotonin leads to an increased susceptibility to depression. This is a theory that has been widely held since the 1960s. For this reason, many medications to reduce the symptoms of depression are believed to act on serotonin levels in the body. Known as selective serotonin reuptake inhibitors (SSRIs), these antidepressants are believed to increase serotonin levels in the brain.

A thought-provoking study on the real effects of antidepressants

So far, the exact functioning of these antidepressants is not known. And this could be explained by the doubt hanging over the link between serotonin and depression. Indeed, according to a new study by researchers at University College London, there is no concrete evidence to certify that there is really a link between serotonin levels or serotonin activity and depression. . To reach this conclusion – which is detailed in the review Molecular Psychiatry – the researchers conducted a comprehensive review covering decades of research on serotonin and depression.

The results suggest that the depression is probably not caused by a chemical imbalance. This finding is very important because it calls into question how antidepressants work for patients. ” Many people take antidepressants because they’ve been led to believe their depression has a biochemical cause, but this new research suggests that belief isn’t based on evidence. said Joanna Moncrieff, lead author of the study, in a statement.

Either way, the researchers admit there are limits to their research. Therefore, it is important not to completely rule out serotonin as a cause of depression. The researchers also say their findings don’t imply that antidepressants don’t work, only that they don’t understand why or how they work. In other words, other research – broader and more in-depth – on the subject must be carried out. Researchers have also highlighted the importance of different decision-making in depression treatments.