When semaglutide (sold as Ozempic for diabetes and Wegovy for obesity) first emerged, the conversation was almost entirely about blood sugar and weight. Then came the cardiovascular data. Then the kidney findings. Then the evidence on dementia risk.
Now, a major new study suggests the drug may have profound effects on mental health too.
The Study
Published in The Lancet Psychiatry on March 18, 2026, the research was conducted by researchers at Karolinska Institutet (Sweden), the University of Eastern Finland, and Griffith University (Australia). They analysed Swedish national health records of nearly 95,000 people diagnosed with depression or anxiety who were also taking diabetes medications between 2009 and 2022.
The team used a sophisticated "within-individual" design — comparing periods when patients took GLP-1 medications against periods when they did not, within the same individuals. This design significantly reduces the risk of confounding, where healthier people might be more likely to both improve and receive medication.
The Numbers
Among people taking semaglutide:
- 42% lower risk of worsening mental health overall
- 44% lower risk of worsening depression
- 38% lower risk of worsening anxiety
- 47% lower risk of worsening substance use disorders
The drug liraglutide (Victoza) showed more modest benefits. Other GLP-1s didn't show the same effects.
How Might This Work?
Researchers believe semaglutide may cross the blood-brain barrier and act on GLP-1 receptors in areas of the brain associated with reward, motivation, and emotional regulation. The drug's well-documented effects on inflammation — a known contributor to depression — may also play a role.
These findings complement earlier research suggesting GLP-1 drugs may reduce cravings and substance use by dampening the brain's reward-seeking circuits.
Important Caveat
This is an observational study. While its methodology is stronger than typical cohort studies, it cannot prove that semaglutide causes mental health improvements. Randomised clinical trials are needed to confirm causation. But the consistency of the findings across depression, anxiety, and substance use — with a large, real-world dataset — is striking.
Sources: The Lancet Psychiatry, March 18, 2026 · The Guardian · Karolinska Institutet news release · Medscape · Science Media Centre
