Hemispheric asymmetry of conflict control in two subtypes of children with attention deficit hyperactivity disorder

OBJECTIVE: To examine the potential hemispheric asymmetry of conflict control in two subtypes of children with ADHD (25 of predominantly inattentive, i.e., ADHD-I; and 31 of combined, i.e., ADHD-C).

METHODS: A cross-modal interference task was used, in which the auditory distractors were provided either from the left ear or from the right ear and they constituted congruent, incongruent or neural relations with targets displayed at the screen center of the computer.

RESULTS: Children with ADHD showed an distinctive pattern of error rate when distractors were provided from the left ear compared with the normal controls, with a significant conflict effect for ADHD (effect size was 4%), F(1,110)=18.16,P<0.001,and no effect for the controls (effect size was 1.2%), F(1,110)=1.59,P>0.1. Moreover, children with ADHD showed a tendency of a reversal inhibition effect (effect size was -1.7%), F(1,110)=3.16,0.05<P<0.1, among whom, this effect were severe significant in children of ADHD-C(effect size was -4.1%),F(1,54)=8.31,P<0.01,which means the error rate was markedly higher in neutral condition than that in the incongruent condition. While the controls showed none of this significant effect (effect size was 1.2%), F(1,110)=1.53,P>0.1.

CONCLUSION: The results suggest that children with ADHD showed atypical pattern of their right hemisphere in conflict control compared with normal children, the atypical pattern of right hemisphere for ADHD-C need to be further studied.