Weight loss drug semaglutide proven safe and effective for people with schizophrenia

Diabetic weight loss medications are effective for people with schizophrenia without affecting psychotic symptoms, University of Queensland researchers have found.

Professor of Psychiatry Dan Siskind said a 36-week trial found semaglutide – the active component in weight-loss drugs such as Ozempic and Wegovy – was effective for people with schizophrenia who often experienced weight gain from taking anti-psychotic medication.

He said patients often stopped taking prescribed medication clozapine because of weight gain, and this finding will help inform clinical treatment guidelines.

People with schizophrenia have a 16-year life expectancy gap compared to the general population which is driven largely by obesity-related illnesses,'' Professor Siskind said.

The study participants on semaglutide lost almost 14 per cent of their bodyweight across the trial, compared to those taking a placebo.

Anti-psychotic medications are associated with high weight gain in patients, leading to poorer quality of life, shorter life expectancy, and poorer medication adherence.''

Dan Siskind, Professor of Psychiatry, University of Queensland 

Professor Siskind, who works clinically as a psychiatrist at Metro South Addiction and Mental Health Services in Brisbane, said the findings were significant and provided world-first evidence that semaglutide is safe and highly effective for weight loss in people with schizophrenia.

The study was investigator-led, meaning no pharmaceutical company was involved.

"Before this study, we did not know if there would be drug-to-drug interactions with semaglutide or any impact on mental state,'' Professor Siskind said.

"We were able to show that semaglutide didn't affect psychotic symptoms or levels of anti-psychotic medications, indicating that it doesn't worsen their psychosis. We found no increased risk or drug interactions.

"The lean mass/fat mass ratio also improved in the semaglutide group, suggesting more fat was lost than non-fatty tissues such as muscle.''

In Australia, semaglutide is not on the Pharmaceutical Benefits Scheme (PBS) for weight loss.

"People with schizophrenia urgently need access to effective treatments for obesity, such as semaglutide,'' Professor Siskind said.

"We would be strongly advocating for access to PBS listing for semaglutide for this population.

"Many people with schizophrenia cannot afford to pay for this out of pocket, and I do have a number of people with schizophrenia on clozapine who use semaglutide for weight loss with support from their families.''

The research is published in Lancet Psychiatry.