83% of preclinical studies showed antidepressant effects from GLP-1 receptor agonists through neuroplasticity and anti-inflammatory mechanisms, but only 1 of 3 human clinical trials showed statistically significant benefits.
83% preclinical positive, 33% clinical positiveStrong preclinical evidence for GLP-1 antidepressant effects hasn't yet translated to convincing clinical trial results — a common pattern that calls for more rigorous human studies.
What the researchers found
Across 26 included studies:
- Preclinical: 15 of 18 studies (83%) showed significant antidepressant-like effects. The mechanisms involved enhanced neuroplasticity, reduced neuroinflammation, and neurotransmitter alterations.
- Observational: 4 of 5 studies reported reductions in depressive symptoms in human patients.
- Clinical trials: Only 1 of 3 showed statistically significant antidepressant effects.
The disconnect between strong preclinical evidence and weak clinical trial results highlights the typical challenge of translating animal findings to human therapeutics, and suggests that more and larger clinical trials are needed before conclusions can be drawn.
Why it matters
Depression is a leading cause of disability worldwide, and existing antidepressants are inadequate for many patients. If GLP-1 drugs — already widely prescribed and well-characterized — could also treat depression, it would be transformative, particularly for the many patients who have both metabolic conditions and depression. The strong mechanistic evidence from animal studies provides a solid biological rationale for pursuing this further.
How the study worked
This systematic review searched MEDLINE, PubMed, and PsychINFO databases for studies investigating GLP-1 receptor agonist effects on depressive symptoms. Both animal and human studies were included. The 26 included studies were categorized as preclinical (18), observational (5), or clinical trials (3) and analyzed for evidence of antidepressant effects and underlying mechanisms.
What this study cannot tell us
The clinical trial evidence is very limited (only 3 trials) and mostly negative. Animal models of depression have poor predictive validity for human outcomes. Observational studies cannot establish causation and may be confounded by weight loss, improved diabetes control, or other factors that independently affect mood. The review does not distinguish between specific GLP-1 agonists. Publication bias may inflate positive results, particularly in preclinical literature.
How to read the evidence
This systematic review synthesizes evidence across preclinical, observational, and clinical studies. While comprehensive, the clinical trial evidence is very limited and mostly negative, making the overall evidence for human antidepressant effects preliminary at best.
When this study was published
Published in 2025 in a leading neuropsychopharmacology journal, this is a very current review capturing the latest evidence as interest in GLP-1 psychiatric effects surges.
The bigger picture
The potential antidepressant effects of GLP-1 drugs are part of a larger revolution in understanding the gut-brain axis and metabolic-psychiatric connections. Depression is increasingly recognized as having inflammatory and metabolic components, which aligns with GLP-1 agonists' anti-inflammatory and neuroprotective effects. If validated, this would add mental health to the growing list of GLP-1 benefits beyond diabetes.
Questions still open
- Are the antidepressant effects seen in observational studies driven by the direct neurological effects of GLP-1 or by secondary benefits like weight loss and improved metabolic health?
- Would higher doses of GLP-1 agonists (as used for weight loss vs. diabetes) show stronger antidepressant effects in clinical trials?
- Could GLP-1 agonists be more effective for depression subtypes characterized by inflammation or metabolic dysfunction?
Common questions
Can semaglutide or other GLP-1 drugs help with depression?
How might GLP-1 drugs affect the brain and mood?
Read the original research
Repurposing glucagon-like peptide-1 (GLP-1) receptor agonists for the treatment of depression: A systematic review of preclinical, observational and clinical investigations.
European neuropsychopharmacology : the journal of the European College of Neuropsychopharmacology, 99, 56-67
Citation
Li, Sophie; Sabbah, Sami George; Kwan, Angela T H; McIntyre, Roger S. (2025). Repurposing glucagon-like peptide-1 (GLP-1) receptor agonists for the treatment of depression: A systematic review of preclinical, observational and clinical investigations.. European neuropsychopharmacology : the journal of the European College of Neuropsychopharmacology, 99, 56-67. https://doi.org/10.1016/j.euroneuro.2025.08.002