Epilepsy Diet Has Lasting Anti-Seizure Effect
Kids have fewer attacks, even after going off high-fat, low-carb diet
MONDAY, Oct. 1, 2001 (HealthDayNews) -- The longest-ever follow-up of children who consume a special diet known to reduce epileptic seizures has produced some surprising results that may shed some light on this mysterious brain disorder.
The study reports that the ketogenic diet, a strict food regimen that involves high-fat, low-carbohydrate meals, not only reduces the frequency of seizures in about half the children who try it, but it also appears to reduce the number of seizures even after the kids have stopped the diet.
According to one pediatric neurology expert, the study could lead to a better understanding of why the diet works, which could ultimately help all patients with epilepsy.
Epilepsy is a neurological disorder affecting more than 2 million Americans. People with this condition are prone to seizures -- bursts of uncontrolled, abnormal brain activity that can cause strange sensations, bizarre behavior, and, sometimes, convulsions. Unless brain surgery can correct an underlying cause of the seizures, there is no known cure for this disorder. Patients can achieve varying degrees of control over their seizures with medications, an implanted "brain pacemaker" called a vagus nerve stimulator, or the ketogenic diet.
Neurologists at Johns Hopkins Medical Institutions followed 150 children with difficult-to-treat epilepsy for between three and six years after the kids started the ketogenic diet.
The children's ages ranged between 1 and 16 when the study started and they had at least two seizures per week, with an average of 410 seizures per month. They hadn't responded to an average of 6.2 different seizure medications.
Of those children, 83 stayed on the diet for at least a full year, 58 stuck with it for two years, 30 stayed for three years and 19 lasted on it four years. Fifteen children stayed with the diet for more than four years, and one child has remained on it for 6.5 years. Most families discontinued the diet because they felt it was ineffective or too restrictive, or because of another illness.
In 1999, three years after enrolling the last child, the researchers asked about the child's current health, seizure frequency, and current epilepsy medications. The survey also looked for information on a child's experience with the diet and why it was discontinued.
Three to six years later, 13 percent of the original 150 children were seizure-free, 14 percent saw their seizure frequency drop by between 90 and 99 percent. Another 17 percent had their seizures reduced by between 50 and 99 percent, and the remainder had their seizures decline by less than 50 percent.
Of the 83 children who remained on the diet for one year, 59 percent had originally been taking two or more medications and 27 percent had been taking three or more drugs. Three to six years later, 34 percent of that group no longer needed anticonvulsant drugs, 37 percent were down to one drug, and only 30 percent were taking two or more medications.
The research appears in the October issue of Pediatrics.
Senior investigator Dr. John Freeman, the director of the Pediatric Epilepsy Center at Johns Hopkins Hospital, says that this is the first time anyone has looked at the effect of stopping the ketogenic diet.
It may be possible that the children grew out of their seizures, says Freeman. "But if you look at the literature, these children who were having 400 seizures a month when they started [the diet] and who had failed on six drugs, had a 10 percent chance of getting their seizures under control with any medication. So you wouldn't expect them to have their seizures under control, let alone to outgrow the seizures."
But Freeman simply doesn't know why the effect appears to persist. "Unfortunately, we don't even know why the effect exists to begin with," he says. Some studies have suggested that the diet forces the body to generate compounds called ketones (hence the name of the diet), which somehow reduce seizure activity when metabolized by the brain.
Right now, there are more questions than answers about how the diet works. And, he adds, "nobody has even begun to approach the question of why its effect persists after you stop."
Freeman says the diet may somehow cause a fundamental shift in the metabolism or physiology of the person's brain. "The diet clearly works different than any of the anticonvulsant medications, but we don't know how any of them work either," he says.
Dr. James Wheless, the director of the Texas Comprehensive Epilepsy Program at the University of Texas Houston Health Science Center in Houston, and a specialist in pediatric epilepsy, agrees that there's little solid evidence about how the diet works.
"Clearly, we know it works, and it obviously works in people where the medicines don't work, and we believe it works very differently," says Wheless, who's familiar with the new study. "If it's helping epilepsy in a totally different manner from how we think our medicines help, then obviously there's a whole other system there that we don't understand. If we did understand that, it could impact the treatment of epilepsy in general."
"The other important point that they address is the safety issue," he notes. "From a safety standpoint, it reinforces what we thought about . . . the safety of the diet."
Wheless says that the biggest dilemma that doctors face when putting children on the ketogenic diet is whether the required high-fat intake puts the child at risk of future heart disease or stroke. However, he says that other studies suggest that the children burn the fats for nourishment, and that despite the seemingly unhealthy nature of the diet, the children's cholesterol levels are only marginally higher than normal.
There were no reported cardiac complications among the children in this study.
Freeman says, "The most outstanding thing about the study was that so many children continued to do well after the diet was stopped, after they had come off medication. That's what exciting and meaningful."
What To Do
For a more comprehensive view of epilepsy, visit the National Institute of Neurological Disorders and Stroke Web site.