After decades of research, there remains no clear evidence that serotonin levels or serotonin activity are responsible for depression, according to a comprehensive review of prior research led by University College London (UCL) scientists.
The major new umbrella review – an overview of existing meta-analyses and systematic reviews – was published on July 20 in the journal Molecular Psychiatry. It suggests that depression is not likely caused by a chemical imbalance, and calls into question what antidepressant medications do. This is because most antidepressants are selective serotonin reuptake inhibitors (SSRIs), which were originally said to function by correcting abnormally low serotonin levels. In fact, there is no other accepted pharmacological mechanism by which antidepressants affect the symptoms of depression.
Lead author Professor Joanna Moncrieff, a Professor of Psychiatry at UCL and a consultant psychiatrist at North East London NHS Foundation Trust (NELFT), said: “It is always difficult to prove a negative, but I think we can safely say that after a vast amount of research conducted over several decades, there is no convincing evidence that depression is caused by serotonin abnormalities, particularly by lower levels or reduced activity of serotonin.
. . .
Professor Moncrieff said: “Our view is that patients should not be told that depression is caused by low serotonin or by a chemical imbalance, and they should not be led to believe that antidepressants work by targeting these unproven abnormalities. We do not understand what antidepressants are doing to the brain exactly, and giving people this sort of misinformation prevents them from making an informed decision about whether to take antidepressants or not.”
