Intended for healthcare professionals


“No convincing evidence” that depression is caused by low serotonin levels, say study authors

BMJ 2022; 378 doi: (Published 20 July 2022) Cite this as: BMJ 2022;378:o1808
  1. Jacqui Wise
  1. Kent

The authors of a large review say there is no support for the hypothesis that depression is caused by lowered serotonin activity or concentrations, and have questioned the reasons behind high prescribing rates of antidepressants.

They say the chemical imbalance theory of depression is still wrongly being put forward by some professionals and the public widely believes it.

Other clinicians say, however, that the notion of depression being because of a simple chemical imbalance is outmoded anyway, and that antidepressants remain a useful option for patients alongside other approaches including talking therapies.

The systematic umbrella review, published in Molecular Psychiatry, looked at the existing overviews of research on serotonin and depression including systematic reviews and meta-analyses.1

Joanna Moncrieff, professor of psychiatry at University College London, consultant psychiatrist at North East London NHS Foundation Trust, and the study’s lead author, 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.”

The review found that research that compared levels of serotonin and its breakdown products in the blood or brain fluids did not …

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