BALTIMORE – Comorbid attention-deficit/hyperactivity disorder persistently affected the cognitive development of children with epilepsy up to 5 or 6 years after the onset of seizures in a prospective case-control study.
In a previous study of the same group of children, Connie Sung and her colleagues found that children with new-onset epilepsy and comorbid ADHD (with or without academic problems) had poorer cognitive performance at baseline and abnormal cognitive development after 2 years, compared with healthy control children and children with new-onset epilepsy but without ADHD.
In the current study, Ms. Sung, a doctoral student in the department of rehabilitation psychology and special education at the University of Wisconsin, Madison, and her colleagues conducted cognitive assessments of 75 children with epilepsy and 62 of their healthy first-degree cousins who served as controls. They gave the children a comprehensive battery of neurologic tests to assess academic achievement, intelligence, language, memory, executive function, and motor function at baseline and at 2 years’ and 5-6 years’ follow-up. The children’s average age at last follow-up was 13 years.
At baseline, ADHD and academic performance were significantly associated with neuropsychological impairment across all cognitive domains. However, children with epilepsy who did not have either ADHD or academic performance problems had "entirely normal" cognition, compared with controls, Ms. Sung reported in a poster at the annual meeting of the American Epilepsy Society.
"This effect at baseline suggests an antecedent neurobiological effect," Ms. Sung wrote.
These trends persisted after 2 years and 5-6 years. Full-scale raw IQ scores after 2 years were approximately 88 for healthy controls and for children with epilepsy without comorbidities, compared with 76 in children with epilepsy and academic performance problems and 68 in children with epilepsy and comorbid ADHD.
At 5-6 years after onset, children with epilepsy and either ADHD or academic problems had significantly worse cognitive trajectories than did controls, but children with epilepsy who did not have these comorbidities had normal cognitive trajectories.
The researchers said that their findings were limited by the study’s relatively small sample size, but the results suggest that specific neurobehavioral comorbidities at the time of the onset of epilepsy appear to be markers for abnormal cognitive development before and after epilepsy.
"These effects are strong and consistent [and] affect all cognitive domains," Ms. Sung wrote.
The researchers are now studying the effects of the presence or absence of ADHD and learning disorders on real-life outcomes such as employment, education, and income, as their study population ages. "These comorbidities may represent early risk factors for later life span complications [in children with epilepsy], opening the possibility for early intervention," Ms. Sung reported.
The study was supported in part by a grant from the National Institute of Neurological Disorders and Stroke. The researchers said they had no relevant financial disclosures.