Medical experts from Cochrane, a World Health Organization affiliate, have published a review on medical marijuana for treating epilepsy, concluding evidence from previous studies is too weak.
Success stories from children with treatment-resistant epilepsy have been widely covered by the media in the past few years. Cannabis and its ingredients have now caught the attention of patients, doctors and research foundations alike.
While studies on cannabis are not easy to conduct, some say research from as early as the 70s supports marijuana as an epilepsy treatment. Alternative medications are still needed, since currently available drugs only work for about two-thirds of patients.
“For the remaining patients, they may wish to try other agents to obtain better control. Marijuana, or cannabinoids, may be one such agent,” write Dr. David Gloss and Dr. Barbara Vickrey of the Department of Neurology at UCLA, who co-authored the Cochrane review.
“Marijuana has been used since the 19th century for patients with epilepsy,” they add. But while cannabis is available in some countries and U.S. states, clinical evidence is sparse.
Published online this month in The Cochrane Library, the authors reviewed the current body of trial data on marijuana treatments and found four studies that were relevant. All involved cannabidiol (CBD), a non-psychoactive ingredient in marijuana, in a randomized clinical setting.
Early CBD Trials
The four studies were conducted between 1978-1990 and included a total of 48 patients. All were too short to meet the review’s primary criteria, which required 12 months of observation, but were still included for their safety results.
The earliest study, conducted in Brazil, involved 9 patients given either 200mg of CBD or placebo daily. 2 of the 4 patients given CBD became seizure free during the three-month study. None given placebo showed any improvement.
Another study, published in 1980, involved 16 patients given 200-300mg of CBD or placebo daily for up to 4 months. 4 of the 8 who received CBD remained “almost free” of convulsions throughout the experiment and 3 other patients showed “partial improvement.” 7 of the 8 given placebo showed no changes.
The later studies, conducted in 1985 and 1990 (unpublished), were less successful, showing little to no improvements from CBD treatment. However, almost all studies found that CBD had “no significant side effects in any of the patients.” Only mild drowsiness was reported by one study.
‘Far From Complete’
Overall, the authors conclude the trials were too small and too short to be considered sufficient by today’s standards.
“The evidence from the four trials is far from complete,” write Dr. Vickrey and Dr. Gloss. “If the question were to be addressed, there would need to be a series of properly designed, high quality and adequately powered trials.”
Though the trials revealed no side effects of CBD other than drowsiness, the authors state: “no conclusions can be drawn about the safety of long term cannabidiol treatment.”