Children with two of the most severe forms of epilepsy can suffer scores of seizures each day, as well as long-term physical and cognitive problems. The two conditions, Dravet and Lennox-Gastaut syndromes, are quite rare but unfortunately very resistant to treatment with current epilepsy drugs.
Now a compound found in marijuana plants has shown promising results in a preliminary study, during which it sharply reduced the number of seizures suffered by these children. Some were even seizure-free after three months of taking the drug, cannabidiol, the research showed.
"We're very encouraged by the data," said Orrin Devinsky, director of the NYU Langone Comprehensive Epilepsy Center and leader of the research. A more rigorous study of cannabidiol's impact has begun and will help determine how effective it really is, he said.
In making cannabidiol, the marijuana plant's psychoactive material (THC) was removed. A 99 percent pure liquid version of the drug was given for three to six months to 137 people with the two syndromes. Most were children (the subjects ranged in age from 2 to 26), and before the experiment they suffered a disturbing average of 95.3 convulsive seizures every month. Convulsive seizures are the more severe, violent kind; people with epilepsy can experience a wide variety of seizures, including some mild enough that they appear to be merely staring into space for a few seconds. Some of the subjects had taken as many as 10 different epilepsy drugs, with little success.
After 12 weeks, 51 percent of the children saw at least a 50 percent reduction in the number of seizures they experienced. The frequency of all types of seizures was down 54 percent in all the patients and by 63 percent in the Dravet syndrome patients. Nine percent of the subjects, and 16 percent of those with Dravet syndrome, were suffering no seizures at all after three months.
Animal studies and anecdotal reports from people who have been making forms of cannabidiol on their own had led researchers to believe that the compound could be effective against the two syndromes, Devinsky said. Some marijuana smokers also claimed that the weed helped curb epileptic seizures.
But it's not entirely clear why cannabidiol might be effective. It may target certain receptors in the brain that are not functioning correctly and contribute to seizures.
A British pharmaceutical company produced the pure form of the drug and supported Devinsky's research. With the THC removed, the children don't get high, and any possible psychological and learning effects are avoided.
But the research had a number of limits. As an "open-label" study, it allowed the researchers and physicians to know what drug was being administered. That means a placebo effect can't be ruled out. A more rigorous "double-blind" study, in which neither the researchers nor the test subjects know whether they're receiving the drug or a placebo, has begun, Devinsky said.
A few of the subjects suffered side-effects that include prolonged or clustered seizures, diarrhea, weight loss, lethargy and liver problems.
Devinsky will present his results at the American Academy of Neurology Conference that begins Friday. As yet, they have not been published.
Devinsky said that fewer than 10,000 people suffer Dravet syndrome in the United States and fewer than 25,000 have Lennox-Gastaut, so any medication developed from cannabidiol would, at least initially, be considered an "orphan drug" targeted at those populations. But if more research showed it to be effective on milder forms of epilepsy, the treatment could have a much bigger market, the 5.1 million people with the condition, about one-third of whom cannot control their seizures with medication.