Introduction: The aim of this study was to investigate the frequency and clinical significance of epileptiform discharges in children with attention deficit/hyperactivity disorder (ADHD).

Methods: We retrospectively analyzed 180 children, who were diagnosed with ADHD and had an EEG recording in Kyung Hee University Hospital. Epileptiform discharges were classified either generalized or focal. We reviewed the age, sex, type of ADHD, presence of epilepsy or not, previous history of seizures (febrile or afebrile), and IQ (intelligence quotient) score including full-scale IQ, verbal IQ, and performance IQ.

Results: Epileptiform discharges were found in 29 (16.1%) children. Of these, 15 (8.3%) showed generalized epileptiform discharges and 14 (7.7%) had focal epileptiform discharges. Rolandic discharges were found in 5 (2.7%) children. Other focal epileptiform discharges were observed in frontal (n=5), temporal (n=1), or occipital (n=3) regions. Among the children with epileptiform discharges and ADHD, 5 children had previous history of epilepsy, and 4 children developed epilepsy later. None of the children without epileptiform discharges suffered from epilepsy. Comparing the children with/without epileptiform discharges, the children with epileptiform discharges were younger (mean age: 108.9±26.1 vs. 120.8±36.8 months, p=0.022), and there were a higher portion of girls in the group with epileptiform discharges (45.0% vs. 14.4%, p=0.045).

Conclusions: We found that 16.1% (29/180) of children with ADHD have epileptiform discharges, and 31.0% (9/29) of them were associated with epilepsy. The clinical significance of subclinical epileptiform discharges in children with ADHD needs to be identified by future research.