Response to methylphenidate in children with ADHD and comorbid anxiety.

Objective: To determine whether comorbid anxiety alters response to methylphenidate (MPH) in children with attention-deficit hyperactivity disorder (ADHD).
Method: Ninety-one children with ADHD were assessed for anxiety. Children were randomly assigned to receive MPH or placebo, titrated to a dose of 0.7 mg/kg, while side effects were minimized. Measures of side effects and behavioral response were obtained from parents and teachers before treatment, after titration to optimal dose, and after 4 months of treatment. These measures, dose of drug, and rate of adherence to assigned medication assignment were compared for nonanxious (ADHD- ANX) and anxious ADHD children (ADHD+ ANX).
Results: Rates of adherence to original medication assignment did not differ between the groups. ADHD+ ANX on both MPH and placebo titrated to a lower dose at the end of titration, although the dose of drug did not differ among the groups after 4 months of treatment. No differential response to MPH between ADHD+ ANX and ADHD- ANX was noted at end-titration or at 4 months on any side effect or behavioral measures.
Conclusions: Comorbid anxiety does not appear to influence development of side effects or behavioral response to MPH when dose is titrated as in standard clinical practice.