Medicines best known for treating diabetes and obesity may have another possible benefit.
New research suggests that semaglutide, the drug used in products such as Ozempic and Wegovy, is linked to a lower risk of psychiatric hospitalization in people with bipolar disorder.
The research was led by Professor Mark Taylor from Griffith University’s School of Medicine and Dentistry. The findings were published in the journal Acta Psychiatrica Scandinavica.
Bipolar disorder is a long-term mental health condition that causes major changes in mood, energy and activity.
People can experience periods of unusually high or irritable mood, known as mania or hypomania, as well as periods of depression.
The World Health Organization estimates that about 37 million people worldwide live with bipolar disorder. The condition can affect relationships, employment, physical health and everyday functioning, and severe episodes sometimes require hospital treatment.
People with bipolar disorder also have higher rates of obesity and diabetes than the general population. Several factors may contribute, including genetics, lifestyle, sleep problems and weight gain associated with some psychiatric medicines.
This overlap has encouraged scientists to investigate whether treatments for metabolic diseases might also influence the brain. One group receiving particular attention is GLP-1 receptor agonists, often shortened to GLP-1 medicines.
These drugs copy the effects of a natural hormone involved in blood sugar control and appetite. They can help the body release insulin when needed, slow digestion and reduce hunger, which is why they are widely used for type 2 diabetes and increasingly for weight management.
The Griffith-led team used nationwide health data from Sweden to examine what happened when people with bipolar disorder took GLP-1 medicines. The study included nearly 15,000 people and covered about 15 years of records.
Rather than simply comparing people who took the drugs with completely different people who did not, the researchers examined periods when the same individuals were using GLP-1 medicines and periods when they were not. This approach can reduce some differences between individuals that might otherwise distort the results.
The clearest finding involved semaglutide. Periods of semaglutide use were associated with a 21% lower risk of psychiatric hospitalization compared with periods when the patients were not using GLP-1 medicines.
Psychiatric hospitalization is an important outcome because admission often reflects a serious worsening of mental health. Fewer hospital stays could therefore indicate better mood stability or a lower risk of severe relapse.
However, the researchers did not find the same association for every medicine in the GLP-1 family. Liraglutide and dulaglutide were not linked to a similar reduction in psychiatric hospitalization.
This difference is important because it suggests researchers should not assume that all GLP-1 medicines have identical effects on mental health. Individual drugs can differ in how long they remain in the body, how strongly they act and potentially how they affect the brain.
Scientists do not yet know why semaglutide might be associated with better outcomes in bipolar disorder. One possibility is that GLP-1 signaling affects biological processes in the brain as well as appetite and blood sugar.
Researchers have proposed that these medicines may reduce inflammation and cellular stress, both of which have been studied in connection with bipolar disorder. Improvements in weight, blood sugar and general physical health could also indirectly support mental well-being.
The study is interesting because bipolar disorder and metabolic disease frequently occur together. A medicine that safely improves physical health while also reducing severe psychiatric episodes would be particularly valuable for this population.
Still, the findings do not prove that semaglutide treats bipolar disorder. This was an observational study using health records, not a clinical trial in which people were randomly assigned to semaglutide or a comparison treatment.
People may start or stop GLP-1 medicines for reasons connected with their overall health, medical care or behavior. Even careful statistical methods cannot remove every possible difference that could influence hospitalization risk.
The researchers also studied hospitalization rather than every aspect of bipolar symptoms. A lower hospitalization rate does not necessarily mean that depression, mania, anxiety, sleep or everyday functioning improved to the same degree.
For these reasons, people with bipolar disorder should not use semaglutide as a psychiatric treatment based on this study alone. Established treatments such as mood-stabilizing medicines and other specialist care remain central to managing the condition.
The study’s major strength is its large nationwide population and long period of observation. Its most important limitation is that an association in health records cannot establish whether semaglutide itself caused the reduction in hospital admissions.
Professor Taylor and his colleagues hope the finding will now be tested in a randomized controlled trial. Such a trial could determine whether semaglutide truly improves bipolar outcomes, which patients might benefit and whether any mental health effect is independent of weight loss or improved diabetes control.
For now, the research opens an intriguing new direction rather than establishing a new treatment. It suggests that a medicine developed for metabolic disease may interact with brain health in ways that scientists are only beginning to understand.
