Weight Loss Drug May Help Treat Bipolar Disorder, Study Finds

Semaglutide has transformed the treatment of diabetes and obesity, but researchers are increasingly interested in what the medicine may be doing elsewhere in the body.

A large study involving people with bipolar disorder has now found a striking association: psychiatric hospital stays were less common during periods when patients were using semaglutide.

The finding comes from research led by Griffith University using nationwide Swedish health data. Scientists followed medication and hospital records involving almost 15,000 people with bipolar disorder who had been prescribed medicines from the GLP-1 family.

The records covered 2009 through 2024, giving the researchers a long period in which to examine patterns.

The study was published in Acta Psychiatrica Scandinavica under the title “Use of glucagon-like peptide 1 receptor agonists and the associated risk of hospitalisation in bipolar disorder, from a nationwide cohort, 2009–2024.” Professor Mark Taylor of Griffith University’s School of Medicine and Dentistry led the research.

Bipolar disorder causes episodes of major changes in mood and energy. During manic episodes, a person may have unusually high energy, need much less sleep, speak rapidly or make risky decisions. During depressive episodes, the same person may experience very low mood, exhaustion, loss of interest and difficulty functioning.

Managing the illness can be challenging because symptoms may return even after long periods of stability. Medicines such as lithium and other mood stabilizers can reduce this risk, while psychological treatment and regular medical care can provide additional support. Severe episodes sometimes require admission to hospital to protect the patient and provide intensive treatment.

An estimated 37 million people worldwide live with bipolar disorder, according to World Health Organization figures cited by the researchers. The condition is also closely connected with physical health problems. People with bipolar disorder have relatively high rates of obesity, type 2 diabetes and cardiovascular disease.

This overlap matters because some psychiatric medicines can increase appetite or cause weight gain, while depression can make physical activity and healthy eating harder. GLP-1 medicines are therefore sometimes prescribed to people with bipolar disorder for diabetes or obesity, even though they are not approved as treatments for bipolar symptoms themselves.

Semaglutide is one of the best-known GLP-1 medicines and is sold under brand names including Ozempic and Wegovy. It acts like a hormone released after eating, helping the body control blood sugar and sending signals that reduce hunger. Scientists have also found GLP-1-related signaling in the brain, raising questions about effects that may have little to do with appetite.

The Swedish data gave researchers an opportunity to explore those questions without starting a new drug trial. They examined periods when individual patients were using GLP-1 medicines and compared them with periods when they were not. This approach can reduce some differences between people because each person’s experience contributes to the comparison.

The clearest result appeared with semaglutide. Use of the drug was associated with a 21% lower risk of being hospitalized for psychiatric reasons. Professor Taylor said the result supports growing interest in whether GLP-1 medicines might offer benefits beyond their established roles in metabolic disease.

Researchers have several ideas about how semaglutide might influence mental health. Bipolar disorder has been linked in some research with inflammation, problems in the way cells handle stress and changes in energy use. GLP-1 signaling may affect some of these processes, creating a possible biological connection between metabolic health and brain function.

Another possibility is that improving physical health indirectly supports mental health. Better blood sugar control, weight reduction or improvements in other health problems could affect sleep, mobility, confidence or general wellbeing. An observational study cannot easily separate these indirect effects from a direct action of semaglutide on the brain.

There was also an important clue that makes the story less straightforward. Two other GLP-1 medicines, liraglutide and dulaglutide, were not associated with a significant reduction in psychiatric hospitalization. If GLP-1 activity alone were responsible, scientists might have expected similar results across more drugs in the group.

This difference could mean semaglutide has properties that matter specifically for the brain. But it could also reflect differences in the people receiving each drug, when the medicines were prescribed, how long patients took them or other factors hidden in health records. The current study cannot determine which explanation is correct.

That limitation is why the researchers are calling for a randomized controlled trial. In such a study, comparable participants could be randomly assigned to receive semaglutide or a control treatment while researchers carefully track mood episodes and hospital admissions. Random assignment would make it much easier to determine whether semaglutide itself causes any psychiatric benefit.

Safety would also need close attention. GLP-1 medicines can cause nausea, vomiting, diarrhea and other side effects, and they are not appropriate for everyone. Using them specifically for a psychiatric condition would require evidence that the mental health benefits clearly outweigh the risks.

For now, people with bipolar disorder should not view Ozempic or Wegovy as established mood treatments. The study did not test whether semaglutide can replace lithium, other mood stabilizers, psychological therapy or standard psychiatric care. Its main contribution is identifying a promising association that deserves a more rigorous clinical test.

The research is especially interesting because bipolar disorder, obesity and diabetes frequently occur together, suggesting that physical and mental health may share biological pathways more often than medicine has traditionally recognized.

The large Swedish dataset makes the signal difficult to dismiss, but association is not the same as proof. If a future randomized trial confirms the 21% reduction in hospitalization, semaglutide could become an important new area of bipolar research; until then, the finding remains promising but preliminary.