Marijuana has been associated with reducing seizures in people with epilepsy for years, but only now is the topic getting more of the scientific scrutiny it deserves. In a recent study, cannabidiol (CBD) reduced the number of seizures by half in a substantial number of children and adults with Lennox-Gastaut syndrome (LGS), a severe form of epilepsy.
GW Pharmaceuticals, a developer of cannabidiol, sponsored the study.
In a press release, study author Dr. Anup Patel, of Nationwide Children’s Hospital and The Ohio State University College of Medicine in Columbus and a member of the American Academy of Neurology, said:
“Our study found that cannabidiol shows great promise in that it may reduce seizures that are otherwise difficult to control. This is important because this kind of epilepsy is incredibly difficult to treat.”
Tracking the Effect of CBD on Seizures
For the study, researchers followed 225 people with LGS for 14 weeks. The participants had an average age of 16 and experienced an average of 85 “drop seizures” (also called atonic seizures) a month.
These types of seizures result in a loss of muscle tone, causing the person’s head or body to suddenly go limp. Though atonic seizures generally last less than 15 seconds, the loss of muscle tone causes the person to fall to the ground, and they may need to wear a helmet or other form of head protection. 
LGS usually first affects patients beginning in childhood, have different types of seizures on a daily basis, and often have learning impairments. 
The participants had also unsuccessfully tried an average of 6 epilepsy drugs and were taking an average of 3 epilepsy drugs during the study.
- One group of participants was given 20 mg per kilogram (mg/kg) of cannabidiol daily.
- A second group received just 10 mg/kg.
- A third group received a placebo.
On average, the group that took the lower dose of cannabidiol had a 37% decrease in seizures. The participants who took 20 mg/kg saw their seizures decrease by half or more.
The placebo group also saw a decrease – about 17%. About 15% had their seizures decline by half or more.
After doing the math, the researchers concluded that participants in the high-dose group were 2.6 times more likely to report their overall condition had improved compared with the those in the placebo group.
Some 94% of those in the high-dose group and 84% of those in the lower-dose group did experience side effects. About 72% of the placebo group said they, too, had side effects. However, the side effects – including loss of appetite and sleepiness – were mild to moderate.  
“Our results suggest that cannabidiol may be effective for those with Lennox-Gastaut syndrome in treating drop seizures. This is important because this kind of epilepsy is incredibly difficult to treat. While there were more side effects for those taking cannabidiol, they were mostly well tolerated. I believe that it may become an important new treatment option for these patients.”
Next, the team plans to seek approval from the FDA to license cannabidiol LGS sometime this year.
The study findings were presented at the American Academy of Neurology’s 69th Annual Meeting in Boston.