Kelly Hughes

Tags:  Medical cannabis; CBD; epilepsy; THC, seizure control.

 

The problem: In epilepsy patients, antiepileptic drugs are unable to control seizures in approximately 30% of those with frequent seizures. In this subset of patients, cannabis and CBD have shown promise, but there is a concern that THC (responsible for the psychotropic effects of cannabis), and some cannabis extracts, may cause severe adverse effects, especially with long term use.

 

Why do this study?  CBD and cannabis-based drugs are now being approved for treating intractable epilepsy, thus it is important to understand just how effective they are. This study reviews numerous papers to evaluate the efficacy of treating this form of epilepsy with CBD and medicinal cannabis.

 

The study: This study reviewed 236 articles and selected 16 for descriptive analysis.  Of these, 4 were selected for meta-analysis. Articles were chosen to specifically answer the question of whether CBD and/or medical cannabis had a therapeutic benefit for epilepsy, regardless of patient age. The selection reviewed was primarily composed of interventional studies, including randomized and double blind studies, which looked at a reduction in seizure severity or frequency.  Consideration was also given to any reported adverse events. Treatment regimens and dosages varied between studies but the outcome measurements reported were similar, allowing for reliable comparison of efficacy.

 

Researchers found that, compared to placebo, treatment with CBD had a meaningful effect on seizure reduction, regardless of the etiology of epileptic syndromes and dosage. Comparisons between medical cannabis and CBD treatment did not show a significant difference in adverse events. When compared over time, adverse events for CBD were more common for short-term compared to long-term treatments, thus favoring long-term therapy. Cannabis extract containing low levels of THC had a beneficial effect on seizure reduction and, when comparing adverse effects, had a safety profile similar to that of pure CBD. In general, the quantity of THC present in treatments was kept low to reduce the risk of adverse effects.  In two examples, patients taking cannabis extract containing THC had adverse effects that disappeared when the treatment was switched to pure CBD.

 

Conclusions:  This review concluded that that CBD is an effective treatment for reducing the frequency of epileptic seizures, that low levels of THC are as safe as CBD, and that adverse effects are more prevalent at the start of CBD treatment.

 

What does this study add?  This analysis combines the results from a number of independent studies; thus the conclusions here can be considered more broadly supported than those drawn from any single investigation.  In grouping these studies together for analysis, this review also demonstrates that therapeutic improvements in seizure frequency appear consistent across different age groups and different etiologies.

 

Funder:  None stated

 

Author conflicts: None declared

 

Commentary: (Kelly Hughes)

 

This review is helpful because it underscores the potential value of CBD in the treatment of a challenging condition.  It’s interesting that there were more adverse events in short-term users, which may mean people develop a tolerance over time.  It could also mean that people who have adverse events stop using, so if you sample longer-term users, that group has fewer side effects.  It’s worth noting that the meta-analysis limited to just 4 studies, and these 4 studies are from the same research group and may or may not have included overlapping samples. That could unfairly bias the calculations. Another group performing a similar systematic review also found that CBD was safe and effective for the treatment of certain forms of epilepsy (specifically those originating from Dravet and Lennox-Gastaut syndromes), which lends support to these conclusions . While these results are quite promising for the use of cannabis and CBD in the treatment of epileptic seizures, more studies are needed to verify these safety profiles for extended treatment.  Based on differences in the type of adverse events reported in different studies, it is possible that these could be related to variations in CBD and cannabis compositions. Therefore, additional studies would be useful to refine the exact formulation to yield maximum benefits with minimal side effects.