Prevalence of epilepsy and attention-deficit hyperactivity (ADHD) disorder: a population-based study.

Epilepsy and attention-deficit hyperactivity disorder (ADHD) were reported to co-occur at rates higher than expected for coincidental findings. This study investigated the prevalence of both disorders in community-based primary care practice. The central database of the second-largest health maintenance organization in Israel was searched for all children aged 6 to 13 years (n = 284 419; 51.5% males) diagnosed as having ADHD according to the physicians' records and/or the filling of at least 10 prescriptions for antiepileptic medications according to pharmacy records. The prevalence of epilepsy in the total population was 5 out of 1000 children, and the prevalence of ADHD was 12.6%. More than one-fourth (27.7%) of the epileptic children were also diagnosed as having ADHD. On multivariate analysis, children with ADHD had almost twice the risk of epilepsy than children without ADHD. This study supports hospital-based findings of a strong interrelationship between ADHD and epilepsy. The high rate of ADHD in Israeli children warrants further investigation.