Meta-analysis confirmed CBD reduces seizures by 33% in treatment-resistant epilepsy | Research

The takeaway

A meta-analysis of 6 randomized trials with 1,034 patients found CBD reduced seizure frequency by 33% and increased the chance of 50% seizure reduction by 20% in Dravet syndrome, Lennox-Gastaut syndrome, and tuberous sclerosis complex.

Neurologists treating refractory epilepsy, families of children with these syndromes, and policymakers evaluating medical cannabis evidence.

33% reduction in seizure frequency vs placebo

What the researchers found

CBD compared to placebo reduced seizure frequency by 33%, increased 50% seizure reduction by 20%, increased seizure freedom by 3%, and improved caregiver-assessed clinical impression by 21% in patients with refractory epilepsy.

Why it matters

This meta-analysis provides the strongest quantitative evidence to date supporting CBD as an add-on treatment for three of the most difficult-to-treat pediatric epilepsy syndromes.

The numbers in context

1,034 patients across 6 RCTs. Seizure frequency reduced 33%. Patients with 50%+ reduction increased by 20%. Seizure-free patients increased by 3%. Caregiver improvement 21%. Total adverse events increased 12%. Serious adverse events increased 16%. Treatment abandonment increased 12%. Transaminase elevation (3x+ reference) increased 15%.

How the study worked

Systematic review with meta-analysis of 6 RCTs (3 primary, 3 open-label extensions) totaling 1,034 patients with Dravet syndrome, Lennox-Gastaut syndrome, or tuberous sclerosis complex. Searched MEDLINE, Cochrane Central, and ClinicalTrials.gov through April 2022. Followed PRISMA guidelines.

What this study cannot tell us

Only 6 RCTs available. The included epilepsy syndromes are rare, so generalizability to other seizure types is uncertain. The increase in serious adverse events and liver enzyme elevations is notable.

How to read the evidence

Strong: meta-analysis of 6 randomized controlled trials with over 1,000 patients.

When this study was published

Published in 2022.

The bigger picture

CBD (as Epidiolex/Epidyolex) is one of the few cannabis-derived medications with robust clinical trial evidence. This meta-analysis reinforces its place in treating the most treatment-resistant forms of epilepsy.

Questions still open

Can the serious adverse event profile be managed with dose optimization? Would CBD be effective in more common forms of epilepsy? Do the open-label extension results reflect the true long-term efficacy, given the lack of blinding?

Common questions

Which epilepsy syndromes were studied?

Dravet syndrome, Lennox-Gastaut syndrome, and tuberous sclerosis complex, three of the most treatment-resistant forms of epilepsy.

Were there significant side effects?

Yes. CBD increased total adverse events by 12%, serious adverse events by 16%, treatment dropout by 12%, and liver enzyme elevations by 15% compared to placebo.

Does this mean CBD works for all seizures?

This evidence applies specifically to Dravet syndrome, Lennox-Gastaut, and tuberous sclerosis complex with treatment-resistant seizures. Results may not generalize to other epilepsy types.

Read the original research

Use of cannabidiol in the treatment of epilepsy: Lennox-Gastaut syndrome, Dravet syndrome, and tuberous sclerosis complex.

Revista da Associacao Medica Brasileira (1992), 68(10), 1345-1357

View on PubMed ↗Publisher’s paper ↗

Citation

Silvinato, Antônio; Floriano, Idevaldo; Bernardo, Wanderley Marques. (2022). Use of cannabidiol in the treatment of epilepsy: Lennox-Gastaut syndrome, Dravet syndrome, and tuberous sclerosis complex.. Revista da Associacao Medica Brasileira (1992), 68(10), 1345-1357. https://doi.org/10.1590/1806-9282.2022D689