Nearly half of adults with severe, drug-resistant epilepsy experienced at least a 50% reduction in seizure frequency after 12 months of cannabidiol (CBD) treatment, according to a study published today in Epilepsia Open.
The [study](https://onlinelibrary.wiley.com/doi/10.1002/epi4.70331), led by Sara Sánchez-Gamino of Hospital Regional Universitario Málaga in Spain, examined medical records from 37 adults with Dravet syndrome, Lennox-Gastaut syndrome or tuberous sclerosis complex. These conditions can cause difficult-to-control seizures that persist into adulthood.
Researchers evaluated CBD as an additional treatment alongside other antiseizure medications. Participants had a median age of 25, and the median follow-up period was 28 months.
At six months, 18 of the 37 patients, or 48.6%, had experienced at least a 50% reduction in seizure frequency. At 12 months, 17 patients, or 45.9%, met that threshold. Using a lower threshold of at least a 25% reduction, the response rate was 59.5% at one year.
The findings also pointed to improvements in other areas. Caregivers reported better alertness, behavior, interaction or daily functioning in 29.7% of patients. These observations were subjective rather than findings from standardized cognitive testing.
The median number of other antiseizure medications decreased from four to three, a statistically significant change. Thirty of the 37 patients remained on CBD at 12 months.
Adverse events occurred in 64.9% of participants and were mostly mild. The most common were drowsiness, abnormal liver function and irritability. Six patients stopped treatment because of adverse events alone or in combination with a lack of effectiveness.
The researchers said the results support CBD’s potential role in treating adults with these complex forms of epilepsy, with outcomes similar to those reported in children.
However, the study was small, retrospective and lacked a control group. Changes in other medications also complicate efforts to isolate CBD’s effects. The authors called for prospective, controlled studies to better establish how much of the observed improvement was attributable to CBD.
