Children with attention-deficit hyperactivity disorder (ADHD) may be successfully treated with stimulant medications. The medications most commonly used are methylphenidate and dexamphetamine. Unfortunately, it is sometimes difficult to determine whether the behaviors seen in children with ADHD are a result of the disorder or the treatment. Efron and colleagues conducted a blinded crossover trial to compare the side effects of methylphenidate and dexamphetamine in children with ADHD.
Children between five and 15 years of age were included in the study if they met Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria for ADHD and had no other neurologic abnormality. Patients were randomized to receive either methyl-phenidate (0.3 mg per kg) or dexamphetamine (0.15 mg per kg) twice daily for two weeks. After a 24-hour washout period, each child began receiving the other study medication. Standardized teacher and parent rating scales were completed, as was a “behavior questionnaire” designed to collect information about side effects and medication effects.
Most of the patients (81.8 percent) were classified as having ADHD-mixed type, 17.6 percent as ADHD-predominantly inattentive and 1.6 percent as ADHD-predominantly hyperactive/impulsive. Patients in the dexamphetamine group were rated as improved by their parents 68.8 percent of the time, and patients in the methylphenidate group were rated as improved 72.0 percent of the time. Certain behaviors were reportedly more frequent before the trial of medication: nightmares, stomachaches and anxiousness decreased in the children taking methylphenidate. Only insomnia increased in children taking dexamphetamine, and only poor appetite increased in children taking either drug. Only 3.2 percent of patients had to discontinue the study medication because of side effects.
The authors conclude that the behaviors often attributed to medication side effects may simply be features of the ADHD itself. The other possibility is that parents who were motivated to have their child diagnosed with ADHD may have overreported symptoms at the beginning of the trial. At any rate, a careful review of symptoms, including those most often associated with use of methylphenidate or dexamphetamine, should be undertaken before prescribing these medications in children with ADHD.
editor's note: Although there is certainly some controversy about overdiagnosis of ADHD and overprescription of methylpheni-date and dexamphetamine in children, this study provides reassurance for those who treat patients with these medications.—g.b.h.