Problems of Diagnosis and the Definition of Comparable Groups: A Neglected Issue in Drug Research with Children

A review of the literature on child psychopharmacology reveals that many studies ignored differences in diagnosis, severity of illness, age, and IQ, which affect the response to treatment. Hyperactivity was often treated as if it represented a uniform group rather than a symptom which occurs with mild to severe disorders. Although reliable criteria may be lacking for the diagnosis of childhood disorders, the author recommends operational definitions to compare results and apply the findings in clinical practice.