Reducing Seizures in Angelman Syndrome

Dietary Treatment Proven Successful in Reducing Seizures in Angelman Syndrome by up to 90 Percent

The Angelman Syndrome Foundation (ASF) is very excited to announce today that clinical research published in Epilepsia on July 10 has found that a low glycemic index treatment (LGIT) is successful in reducing seizures in individuals with Angelman syndrome. Seizures are a potentially life-threatening symptom that 90 percent of individuals with Angelman syndrome experience and are very difficult to treat. The research, which was funded by the ASF, has widespread, positive implications for the Angelman syndrome community because of the relatively low risk and ease of implementing this type of dietary treatment regimen, particularly compared to other more stringent dietary treatments.

“The purpose of our research was to assess the effectiveness of the LGIT’s high-fat, low-carb diet for the treatment of seizures in pediatric patients with Angelman syndrome, and the research was even more successful than we had anticipated,” said Dr. Ron Thibert, D.O., neurologist and pediatrician at Massachusetts General Hospital, and leader of the group that embarked on this clinical research study. “This was the first study assessing LGIT for this use in this population and the results are very exciting, particularly because the similar ketogenic diet is very strict and difficult to maintain on a daily schedule, and while it can provide similar results, it can also create additional side effects. We are thrilled that the LGIT can provide even more hope for families of individuals with Angelman syndrome.”

The LGIT is a high-fat, limited-carbohydrate diet that was administered to six children with Angelman syndrome, ranging from one to five years of age, for a period of four months. All participants experienced a decrease in seizure frequency, with five of the six exhibiting a more than 80-percent reduction, and all experienced no significant adverse effects. Five of the six participants remained on the LGIT after completion of the trial, and after one year, experienced a 90-percent reduction. A neurologist and dietician conducted clinical examinations before and during the trial, which also included electroencephalography (EEG) and neuropsychological assessments. These assessments also indicated improvement, or a decrease, in seizure activity.

“In addition to seizure reduction, parents also noted developmental gains, and although these gains were not statistically significant on neuropsychological assessment, it illustrates the effectiveness of this treatment and may indicate its compatibility with treatments for other symptoms or effects of Angelman syndrome,” said Thibert. “Furthermore, the results indicate a potentially higher degree of effectiveness for LGIT for the Angelman syndrome population than that observed in the general epilepsy population.”

The staples of the LGIT diet are meats and cheeses, which provide a higher fat intake and lower carbohydrate intake, as well as select fruits and vegetables. The purpose of the diet is to reduce the total carbohydrate intake and consume carbohydrates that have less sugar, which ultimately helps keep patients’ insulin levels stable and low. The LGIT does not require special preparation of the foods used.

“We are thrilled with the results of this clinical study, as our ultimate goal is to fund research that seeks to improve the quality of life of individuals with Angelman syndrome,” said Eileen Braun, executive director of the ASF. “Families who are interested in learning more about this study are welcome to contact our office, and we will put them in touch with the appropriate resources to further explore this possible treatment.”

The LGIT clinical research study was conducted by Ronald L. Thibert, Heidi H. Pfeifer, Anna M. Larson, Annabel R. Raby, Ashley A. Reynolds, Amy K. Morgan and Elizabeth A. Thiele at the Department of Neurology, Pediatric Epilepsy Program at Massachusetts General Hospital.

For more information about this research study, please contact the ASF at or 800-432-6435, or contact Massachusetts General Hospital’s Pediatric Epilepsy Program.