Longitudinal impact of cannabidiol on EEG measures in subjects with treatment-resistant epilepsy.

Abstract Objective To assess the longitudinal impact of highly purified cannabidiol (CBD) on the electroencephalogram (EEG) of children and adults. Methods Participants received an EEG prior to starting CBD, after approximately 12 weeks of CBD (FU1) and after approximately one year of CBD therapy (FU2). Longitudinal changes in five EEG measures (background frequency, focal slowing, reactivity, frequency of interictal, and ictal discharges) were examined following CBD exposure. Data were compared between pediatric and adult groups at two follow-up time points and within groups over time. Population-averaged models with generalized estimation equations or linear mixed effects models were used to analyze data where appropriate. Correlation analysis was used to assess any association between changes in seizure frequency and changes in EEG interictal discharge (IED) frequency. An alpha level of 5% was used to assess statistical significance. Results At FU1, the adult group showed significant decrease in IED/minute (IDR 0.07, 95% CI [0.04, 0.14], P  Significance This longitudinal EEG study shows that highly-purified plant-derived CBD has positive effects on interictal epileptiform discharge frequency but no effects on other EEG measures. The effect of CBD does not appear to be dose or treatment-duration dependent.