Neuropsychological endophenotypes in ADHD with and without epilepsy

Attention-deficit hyperactivity disorder (ADHD) is a frequent comorbidity in children with epilepsy. Despite similarities in behavioral manifestations of inattention and hyper-activity, it is unclear whether the neuropsychological endophenotypes of children with developmental ADHD differ from those with ADHD in the context of epilepsy. The present study compared groups of clinically referred children with both ADHD-Inattentive subtype (ADHD-I) and ADHD-Combined subtype (ADHD-C) to children with ADHD-I and ADHD-C and epilepsy on neuropsychological measures of intellectual functioning, auditory attention, working memory, and sustained attention and response inhibition. Those with ADHD and epilepsy performed more poorly on measures of intellectual function (e.g., Full-Scale IQ, Verbal IQ, Performance IQ) as well as auditory attention and working memory. Differences across the groups were also seen on a continuous performance test. Follow-up correlational analyses showed that variables such as seizure frequency and number of antiepilepsy medications predicted cognitive dysfunction in the epilepsy groups. Overall results suggest that the neuropsychological endophenotypes in developmental ADHD versus ADHD in epilepsy differ with seizure-related variables predicting cognitive dysfunction.