This study has no clear evidence that depression is caused by decreased serotonin levels.
A new review looking at existing studies suggests this condition is unlikely to be caused by a chemical imbalance and casts doubt on the effectiveness of antidepressants.
Research shows that the findings are important because 85-90% of the general public believe that depression is due to a decrease in serotonin or a chemical imbalance.
Most antidepressants are selective serotonin reuptake inhibitors (SSRIs), initially thought to work by modifying abnormally low levels of serotonin.
There is no other accepted way that antidepressants affect symptoms of depression.
Lead author Joanna Moncliffe, Professor of Psychiatry at UCL, is a Consultant Psychiatrist at North East London NHS Foundation Trust (NELFT).
He states, “It’s always hard to prove negative, but decades of extensive research show no conclusive evidence that depression is caused by abnormalities in serotonin, especially low levels or decreased activity of serotonin. I can tell.
The popularity of the “chemical imbalance” theory of depression was consistent with a significant increase in the use of antidepressants.
Antidepressant prescriptions have increased dramatically since the 1990s, with one in six adults and two per cent of adolescents being prescribed antidepressants in a particular year in the UK.
“Many people take antidepressants because they believe that depression has a biochemical cause, but this new study suggests that this belief is not based on evidence.
Professor Moncrief said:
“We believe that this situation is due in part to the false belief that depression is caused by chemical imbalances.
“It is time for the public to know that this belief has no scientific basis.”
The Umbrella Review reviewed all relevant published studies in the major areas of serotonin and depression research.
In total, tens of thousands of participants participated.
One of the findings was that studies comparing levels of serotonin and its breakdown products in blood or cerebrospinal fluid showed no difference between people diagnosed with depression and healthy people.
The authors also reviewed studies of artificially lowered serotonin levels in hundreds of people.
These studies are cited to show that serotonin deficiency is associated with depression.
However, a 2007 review of existing studies and a sample of recent studies showed that lowering serotonin in this way did not cause depression in hundreds of healthy volunteers.
Other studies have investigated the effects of stressful life events and found that the more stressful events a person experiences, the more likely they are to develop depression.
An early study found a link between stressful events, the type of serotonin transporter gene a person has, and the likelihood of depression.
However, larger and more complete studies suggest that this was a false conclusion.
From these findings, the authors conclude that “there is no hypothesis that depression is caused by decreased serotonin activity or concentration.”
Some evidence suggests that believing that depression is caused by chemical imbalances leads people to take a pessimistic view of their potential for recovery and their ability to control their moods without medical assistance.
Studies have shown evidence from other studies that people who used antidepressants had lower levels of serotonin in their blood.
The scientists say this suggests that some evidence is consistent with long-term use of antidepressants that can lower serotonin levels.
This may mean that an increase in serotonin produced by some antidepressants in the short term can cause compensatory changes in the brain that have the opposite effect in the long term.
“I don’t understand what antidepressants do to the brain, and if I give people this kind of false information, they will make informed decisions about whether or not to take antidepressants,” Professor Moncrief said. You won’t be able to do it.”
The researchers caution that anyone considering taking antidepressants should seek the advice of a healthcare professional.
The findings are published in Molecular Psychiatry.
A spokesman for the Royal College of Psychiatrists said: “Antidepressants work differently from person to person, and the reasons are complex. Patient care is therefore based on the needs of each individual and it is important to review regularly.”
“Continued research in the treatment of depression is important for a better understanding of how medications work and how effective they are.
Medicine must be available to all who need it. We do not recommend that you stop taking antidepressants based on this review. It is also advisable to contact your doctor if you have any questions about your medication.
Source: Metro
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