Will Cannabis Oil Really Treat Seizures?

Report of a chemical called cannabidiol (CBD) had reduced the seizures of a 6-year-old girl from near-death levels to almost zero sent desperate patients everywhere on a frenzied quest for treatment.

According to several media outlets, a patient was suffering 300 grand mal seizures per week and had lost the ability to walk, talk, and eat. Existing epilepsy medication had failed her. But CBD—a component of cannabis that does not trigger the plant’s characteristic high—reduced her episodes to a few per month, and, as her parents told reporters, ushered in a full cognitive recovery.

By most estimates, existing seizure medications fail about one-third of all sufferers, either because the drugs don’t stop the seizures or because the side effects are too severe. As story spread, families with loved ones suffering from this type of epilepsy (which can range from seriously debilitating to life-threatening) began relocating from states where CBD could not be legally obtained to states where it could. At least some of them reported similarly miraculous responses to it. Many Marijuana Doctors in Florida and Other states are prescribing this medicine in full speed. So when we reported earlier this month that a new National Academy of Sciences report—the most in-depth analysis of marijuana research to date—concluded that there was not enough evidence to say that cannabis oil could actually treat epilepsy, some people were surprised:

How could the panel draw such a conclusion? Isn’t the patients case, and others like it, proof enough that cannabis oil can succeed for epilepsy patients where so many other treatments have failed?

Because readers asked, and because this particular conclusion (one of almost 100 that the academy drew from their scientific review) is a good window into the whole report and the larger debate surrounding Florida Medical Marijuana Doctors, we decided to take a closer look.

Evidence Considered By The Panel

The reviewers restricted their evaluation to studies that involved humans, excluding any evidence from studies done on animals. That decision was based on sound scientific rationale (animal, or “pre-clinical,” studies can give us important clues about how a chemical might behave, not whether it will be safe or effective for humans). But limiting the studies in this way left the reviewers with some pretty slim pickings.

There were just three clinical studies where doctors treated patients with CBD and measured whether and by how much those patients’ seizures were reduced. The largest of those studies included a total of 162 patients, treated with 99 percent CBD oil extract for 12 weeks; it found that CBD worked about as well as existing anti-epilepsy medications do in treatment-resistant sufferers.

CBD reduced seizures by a monthly average of 36.5 percent; only five patients saw their motor seizures completely disappear during the study period, and only two patients became completely seizure-free.

Why That Evidence Was Deemed Insufficient

For three reasons, mainly.

First, there was simply not enough of that kind of evidence. FDA-approved drugs are usually deemed effective or ineffective based on large-scale clinical trials that study hundreds to thousands of patients over several years. These studies followed only a few hundred patients in all, and for only a few months. 

Second, the studies in question did not include placebo controls. That is, all of the study participants were given actual CBD, and they knew they were getting it. Other research has found that the placebo effect can be especially strong when it comes to Florida Medical marijuana. In one study, patients of families who moved to Colorado for cannabis oil treatment were twice as likely to report a substantial reduction in seizures as those patients who already lived in the state.

The third major reason the studies were deemed insufficient involves drug interactions. Most of the patients in the studies we’re talking about were taking other anti-epilepsy drugs, such as clobazam and valproate, and it turns out that CBD is very good at blocking the liver enzymes that normally break down those other drugs. This drug interaction makes it impossible to say whether reduced seizure incidence seen in study participants was due to CBD by itself or whether it was simply the result of those other medications staying in the system for longer stretches.

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