Mental Retardation and ADHD!

To the Editor.— This letter cautions the general practitioner about prescribing methylphenidate to children with mental retardation, despite the reported utility in nine patients.1 Methylphenidate is understood to be an effective medication for treatment of children who have attention-deficit hyperactivity disorder (ADHD), characterized by a developmentally inappropriate attention span, level of impulsiveness, and motor activity. For the general practitioner, ADHD typically is identified in children with normal neurodevelopment. Because children with mental retardation may have attention spans, impulse control, and activity levels inappropriate for their chronologic age, albeit appropriate for their underlying level of cognitive function, we are concerned about the general practitioner's ability to identify ADHD in children with mental retardation.