The present study compared performance of children with
Attention-Deficit/Hyperactivity Disorder (ADHD) and high functioning
autism (HFA) with that of controls on 4 tasks assessing 2 components of
motor control: motor response inhibition and motor persistence. A total of
136 children (52 ADHD, 24 HFA, 60 controls) ages 7 to 13 years completed 2
measures of motor inhibition (Conflicting Motor Response and Contralateral
Motor Response Tasks) and 2 measures of motor persistence (Lateral Gaze
Fixation and NEPSY Statue). After controlling for age, IQ, gender, and
basic motor speed, children with ADHD performed significantly more poorly
than controls on the Conflicting Motor Response and Contralateral Motor
Response Tasks, as well as on Statue. In contrast, children with HFA
achieved lower scores than controls only on measures of motor persistence,
with no concomitant impairment on either motor inhibition task. These
results are consistent with prior research that has demonstrated
relatively spared motor inhibition in autism. The findings highlight the
utility of brief assessments of motor control in delineating the unique
neurobehavioral phenotypes of ADHD and HFA. (JINS, 2006,
12, 622–631.)