MOTOR PREPARATION, MOTOR EXECUTION, ATTENTION, AND EXECUTIVE FUNCTIONS IN ATTENTION DEFICIT/HYPERACTIVITY DISORDER (ADHD)

Abstract

Attention and executive functions were investigated in medicated and unmedicated children with ADHD combined type using a novel selective reaching task. This task involved responding as rapidly as possible to a target while at times having to ignore a distractor. Results indicated that unmedicated children with ADHD showed slow and inaccurate responding. Slow responding reflected problems at the stage of movement preparation but not movement execution. An attentional impairment, rather than a motor planning problem per se, appeared to underlie the slow movement preparation. Inaccurate responding reflected problems with response inhibition and selective attention, impulsivity, set-shifting, and difficulties in maintaining vigilance. Although medicated children with ADHD did not show slow movement preparation, they did show some response inaccuracy, resulting especially from impulsive responding.These findings suggest that ADHD is characterized by slow motor preparation (but not motor execution), and deficits in selective attention, vigilance, and executive functions. Preliminary results suggest that stimulant medication may resolve some of these motor, attentional and executive function deficits.

We gratefully acknowledge the assistance of Claire Graham and Judy Matulick at Frankston Child and Adolescent Mental Health Service (Southern Health) in the recruitment of research participants. Many thanks also to Maree Farrow in the Psychology Department at Monash University and two anonymous reviewers for their helpful comments on this manuscript.

Keywords:

• ADHD
• executive function
• selective attention
• vigilance
• motor preparation
• neuropsychological profiles

Notes

We gratefully acknowledge the assistance of Claire Graham and Judy Matulick at Frankston Child and Adolescent Mental Health Service (Southern Health) in the recruitment of research participants. Many thanks also to Maree Farrow in the Psychology Department at Monash University and two anonymous reviewers for their helpful comments on this manuscript.

Note that there is no target condition in the no-reach task, because whenever a target is present (distractor + target condition) and the participant responds, this is considered to be correct, and no distractibility errors are recorded.