ADHD News & Research

Study: Depression Not Caused by Low Serotonin After All

Depression is not correlated with low serotonin levels, finds an umbrella study that fundamentally challenges long-held scientific understandings of depression and antidepressant medications.

July 25, 2022

Low serotonin levels are not associated with depression, finds a Molecular Psychiatry study that challenges long-held psychiatric understandings of depression and raises questions about the efficacy of selective serotonin reuptake inhibitors (SSRIs), widely prescribed antidepressants that work by increasing serotonin levels1.

The research, which evaluated 17 meta-analyses and reviews, was the first to synthesize and comprehensively examine studies on serotonin levels, receptors, related genes, and precursor molecules. Its researchers found no evidence for low serotonin-related depression.

The study authors are hopeful that discrediting the serotonin-depression hypothesis, believed by 80% of the general public, will change conversations about emotions and mood disorder. Without the assumption that depression is entirely chemical, they argue, people with depression may feel more optimistic about their ability to self-regulate and manage their symptoms.

In debunking the influential serotonin-depression theory, the new research has sparked new questions about our scientific understandings of depression. Thirteen percent of American adults take SSRIs, a class of antidepressants that were thought to fight depression by increasing serotonin levels2. Their method of action is now unknown, though the study authors hypothesize that an amplified placebo effect may be behind the efficacy of SSRIs. The authors call for more research on the effects of drugs on neurotransmitters and other possible causes of depression.

View Article Sources

1Moncrieff, J., Cooper, R.E., Stockmann, T. et al. The serotonin theory of depression: a systematic umbrella review of the evidence. Mol Psychiatry (2022).
2Brody DJ, Gu Q. Antidepressant use among adults: United States, 2015–2018. NCHS Data Brief, no 377. Hyattsville, MD: National Center for Health Statistics. 2020.