“Bariatric surgery, which involves altering your digestive system, has become a more common treatment for weight loss,” said study author Jorge G. Burneo, MD, MSPH, of Western University in London, Canada, and a Fellow of the American Academy of Neurology. “While bariatric surgery is an effective treatment for obesity and obesity-related chronic conditions like high blood pressure and type 2 diabetes, our research found that bariatric surgery recipients have an elevated risk of epilepsy.”

Researchers examined health records from Ontario, Canada, to identify people who had bariatric surgery during a six-year period. After excluding people with a history of seizures, epilepsy, psychiatric disorders, or drug or alcohol abuse, they included in the study 16,958 people who had bariatric surgery. They were compared to 622,514 people with obesity who did not have bariatric surgery. Participants were followed for a minimum of three years.

A total of 73 people, or 0.4%, of those who had bariatric surgery developed epilepsy, compared to 1,260 people, or 0.2%, of those who did not have the surgery. After adjusting for other factors that could affect the risk of epilepsy, such as diabetes and high blood pressure, researchers found the estimated rates of epilepsy were 50 per 100,000 person-years among people who had bariatric surgery and 34 per 100,000 person-years among those who did not have bariatric surgery. Person-years represent both the number of people in the study and the amount of time each person spends in the study.

People who had bariatric surgery had a 45% increased risk of developing epilepsy compared to people who did not have bariatric surgery. People who had a stroke after their bariatric surgery were 14 times more likely to develop epilepsy than those who did not have a stroke.

“When considering having bariatric surgery, people should talk to their doctors about the benefits and risks,” Burneo said. “While there are many health benefits of weight loss, our findings suggest that epilepsy is a long-term risk of bariatric surgery for weight loss. Future research should investigate epilepsy as a potential long-term complication of bariatric surgery, exploring the possible effects of this procedure.”

A limitation of the study is that researchers were unable to measure obesity status or body mass index (BMI) throughout the study and researchers say some obesity-related conditions could affect epilepsy risk.

The study was supported by the Ontario Ministry of Health and Ministry of Long-Term Care and Western University.