Purpose: Approximately 1/3 of children with epilepsy also suffer from attention deficit/hyperactivity disorder (ADHD), which often includes deficits in working memory. Methylphenidate (MPH) can improve the behavioral difficulties in children with ADHD. However, it is not yet clear whether there are specific neurobehavioral differences between children with combined epilepsy/ADHD and children with developmental ADHD and whether MPH shows comparable neurofunctional effects in working memory task-induced brain activation in both patient groups.

Method: Eleven boys with diagnosed epilepsy/ADHD, 14 boys with behavioral ADHD and 12 healthy controls (aged 9–14 years) were investigated using fMRI; once with medication and once without. In order to measure working memory performance, the popular N-back paradigm was used and scans were recorded on a 3T human head scanner.

Results: Healthy controls performed significantly better than both patient groups without medication, whereas patients’ performance improved to normal after the intake of MPH. On the functional level healthy controls showed more activation in frontal, parietal and cerebellar regions than both patient groups. Within the patient groups there was no enhanced activation detectable due to medication.

Conclusion: These data indicate a clear effect of MPH on a behavioral level. However, this effect is not reflected by changes in functional brain organization. In contrast to healthy controls, patients showed decreased activation during N-back tasks in both conditions. Due to the behavioral and functional similarities of the two patient groups, data indicate that the neurobehavioral dysfunctions of working memory are comparable in children with epilepsy and/or ADHD.