Cannabidiol comes from the cannabis plant. It does not contain the part of cannabis that gives a ‘high’ – the psychoactive part.
The researchers, Dr Devinsky and colleagues, wanted to look at whether cannabidiol could be used to treat seizures in Dravet syndrome. This condition is a rare and severe form of epilepsy which is difficult to treat with epilepsy medicines.
The study was carried out on 120 children and young adults (aged 2-18 years) with Dravet syndrome across 23 centres across Europe and the US. They all had seizures not responding to epilepsy medicines. The children were randomly chosen to either be given cannabidiol or a placebo – a similar treatment but which doesn’t have an effect on health. The children were studied over 14 weeks.
The study found that cannabidiol reduced the number of children’s convulsive seizures from around 12 a month on average, to about 6. The group who had placebo treatment saw hardly any fall in seizure numbers. About 2 in 5 children had the number of their convulsive seizures fall by half. According to the study, for the majority of children and young adults in the group taking cannabidiol, overall health improved.
However, while cannabidiol was successful in reducing the number of convulsive seizures, it did not have much of an effect on other types of seizures, the study found. A few side-effects were linked to cannabidiol, including diarrhoea, vomiting, tiredness, drowsiness and fever.
Professor Helen Cross from Great Ormond Street Hospital in London, who was one of the researchers on the study, said: “The data are really exciting. They show cannabidiol to have significant benefit in [convulsive] seizure control in Dravet syndrome, a particularly complex epilepsy syndrome with a poor prognosis for seizure control and neurodevelopmental outcome. It is a major step forward for this population.”
Simon Wigglesworth, deputy chief executive of Epilepsy Action said: “We welcome this exciting new research showing positive results in reducing [convulsive] seizures for patients with Dravet syndrome. We hope this will lead to this new medicine being made available to patients in the not-too-distant future.
“Cannabidiol is the non-psychoactive part of cannabis which may have anti-epileptic properties. There has recently been encouraging research findings in this area, which could enable people with rare forms of epilepsy to gain better seizure control. The study focused on Dravet syndrome which occurs in between 1-2 in every 500 children with epilepsy. However, it is one of the epilepsy syndromes which is most resistant to epilepsy medicines.”
The research is published in The New England Journal of Medicine.