Cannabis oil helped 19 patients with drug-resistant epilepsy achieve seizure freedom for up to 1,694 days, with many remaining seizure-free for over a year, according to new research.
The study, published in Frontiers in Neuroscience, examined patients treated at a Toronto neurology clinic who had previously failed to respond to at least two conventional anti-seizure medications – a condition known as drug-resistant epilepsy (DRE).
The median duration of seizure freedom was 245 days, with five patients maintaining continuous seizure-free periods for at least one year. Before treatment, patients averaged 6.5 seizures per month.
The research involved 15 children and four adults with various types of epilepsy, representing 10.9% of the 174 drug-resistant epilepsy patients treated at the clinic.
Drug-resistant epilepsy affects approximately 30% of epilepsy patients, who are diagnosed after failing to achieve seizure freedom from two separate anti-seizure medications. These patients experience higher hospitalisation rates, mortality rates, and psychological complications, including depression and anxiety.
The study found that 4% of the paediatric patients achieved at least one year of seizure freedom – a significant improvement over the less than 1% success rate typically seen with conventional medications after multiple treatment failures.
Cannabis-based medicines work through entirely different mechanisms than conventional anti-seizure medications, which can cause unwanted side-effects including tiredness, stomach pain, weight gain, headaches, and diarrhoea. Whilst traditional drugs like carbamazepine and valproic acid reduce electrical brain activity by targeting ion channels and neurotransmitters, cannabis-based products modulate the endocannabinoid system.
The cannabis treatments also produced milder side effects compared to conventional medications, with patients reporting mainly drowsiness and dry mouth rather than the more severe complications associated with traditional drugs.
Most patients (14 out of 19) used a combination of CBD and THC, whilst five received CBD-only treatments. The typical CBD dose was around 7mg per kilogram of body weight daily, with THC doses averaging 0.31mg per kilogram daily.
Thirteen patients continued taking conventional anti-seizure medications alongside cannabis treatment, whilst three were able to discontinue all other medications entirely.
Nearly 90% (17 out of 19) of patients reported improved quality of life, and no severe adverse events were recorded during the treatment period.
Previous studies using cannabis have often concentrated their efforts on treating patients with specific types of epilepsy, such as Dravet syndrome and Lennox-Gastaut syndrome, primarily using CBD. This research included patients with various epilepsy types using a combination of THC and CBD.
The researchers acknowledged the study’s limitations, including its small sample size and lack of controlled design, and called for larger double-blind trials to confirm these findings.
“Given the significant burden that ongoing seizures pose on morbidity, mortality, quality of life, and healthcare costs, the authors call on the epilepsy research community to prioritise the identification of this population’s shared characteristics,” the researchers wrote. “Focusing on the identification of their chemical and genetic biomarkers may translate clinically in the guidance of treatment choice and the prioritization of CBPMs in treatment pathways for DRE. Given the comparative SF data in the published literature, future double blind, placebo-controlled studies should also assess whether CBPMs should be prioritized as first-line medical therapy for DRE cases that lack established, evidence-based treatment options.”
They also advocated for improved access to cannabis-based medicines for patients with drug-resistant epilepsy, given the treatment’s potential to achieve seizure freedom where conventional medications have failed.
The study concludes that cannabis medicines can be an effective tool in the treatment of DRE in multiple subtypes of epilepsy, and agree with the conclusions of previous studies that they can be used to attain the goal shared by patients and caregivers of achieving seizure free status – the primary goal shared by patients and caregivers managing drug-resistant epilepsy.
