Although the findings from recent controlled studies suggest that
methylphenidate is a safe and effective treatment for many children with
attention-deficit hyperactivity disorder (
ADHD) and comorbid
tic disorder, relatively little is known about
drug effects on school behavior. Thirty-four prepubertal children with
ADHD and
tic disorder received placebo and 3 doses of
methylphenidate (0.1, 0.3, and 0.5 mg/kg) twice daily for 2 weeks each under double-blind conditions. Treatment effects were assessed using direct observations of child behavior in classroom, lunchroom, and playground settings. Treatment with
methylphenidate resulted in marked reductions of hyperactive, disruptive, and aggressive behavior, which was evident even for the 0.1 mg/kg dose. There were no "nonresponders." The only observed changes in
tics were a small but statistically significant increase in the frequency of
motor tics (classroom, 0.1 mg/kg dose) and a tendency for fewer
vocal tics (lunchroom). However, these changes in
motor tic frequency were not perceived by care providers as a worsening in the severity of the child's
tic disorder. Most dose-response relationships were linear, but the mean (operationally defined) minimal effective dose (MED) was 0.3 mg/kg. In summary, the findings support the conclusions that (1)
methylphenidate suppresses
ADHD behaviors in the classroom and aggressive behavior in all settings and that (2) a low dose may have a weak exacerbation effect on the frequency of
motor tics; but, in general, the majority of youngsters do not experience clinically significant
tic worsening with a MED.