Effects of methylphenidate on impulsive responding in children with attention-deficit hyperactivity disorder

The present investigation examined the effects of methylphenidate on impulsivity in children with attention-deficit hyperactivity disorder (ADHD). A task was designed to measure empirically the ADHD child's proclivity to blurt out incorrect answers before giving a final and/or correct response. Twenty-six ADHD children referred for double-blind placebo-controlled assessment of medication responsiveness and 14 non-ADHD controls were given a visual search word-matching task to assess impulsive responding. An analysis of covariance showed that ADHD children on methylphenidate made fewer impulsive errors than ADHD children on placebo. The control group made fewer impulsive errors than the ADHD children in the placebo condition, but the performance of the ADHD children on medication approximated the performance of the children without ADHD. These preliminary findings suggest that the word-matching task may be a useful tool for assessing impulsive responding and determining the benefits of stimulant medication on impulsivity.