Please use this link to access this publication. 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...