Treatment effects of methylphenidate on behavioral adjustment in children with mental retardation and ADHD

The effects of stimulant medication treatment were investigated in children with mental retardation (MR) and attention-deficit/hyperactivity disorder (ADHD).

Parent and teacher behavioral ratings and reports of side effects were obtained for children (N = 24, mean age = 10.9 years, SD = 2.4) during a placebo-controlled, double-blind, crossover treatment trial with 0.15 mg/kg, 0.30 mg/kg, and 0.60 mg/kg b.i.d. dosages of methylphenidate.

The most significant improvements occurred at the 0.60 mg/kg methylphenidate dose for teacher ratings of inattention (p =.024), hyperactivity (p <.001), aggression (p <.001), and asocial behavior (p =.009). No significant improvements, relative to placebo, occurred at the 0.15 mg/kg dosage. Of interest, nearly all significant medication-related behavioral improvements were detected by teachers. However, parents were sensitive raters of side effects, noting more sleeping problems and loss of appetite at the 0.60 mg/kg dose compared with placebo.

These results suggest that symptoms of ADHD can be treated successfully in children with ADHD/MR, and consistent with MTA study results, higher doses were most effective. Furthermore, these improvements were not accompanied by increases in symptoms such as staring, social withdrawal, or anxiety.