Hemispheric Functioning in Children With Subtypes of Attention-Deficit/Hyperactivity Disorder

Objective: The authors investigated line bisection performance in children with Attention-Deficit/Hyperactivity Disorder (AD/HD) subtypes. Previous research with neurotypical children found a rightward bias with right-hand use and a leftward bias with left-hand use; however, research with AD/HD participants has failed to similarly measure the effects of hand use, which was the focus of this study. Method: Line bisection was used to measure differences in right hemisphere functioning in children (7 to 12 years) with AD/HD-I and AD/HD-C. Results: Initial AD/HD group findings (without subtype differentiation) replicated previous research. However, further subtype analyses showed that the ADHD-I and ADHD-C groups perform significantly differently. Specifically, the ADHD-I group showed a leftward bias, irrespective of hand use, and the ADHD-C group showed a rightward bias, irrespective of hand use. Conclusion: These findings suggest that the subtypes represent two distinct disorders and that, unlike ADHD-C, ADHD-I may not be the result of right hemisphere dysfunction.