The nosology of attention-deficit hyperactivity disorder.

This study examined five central issues regarding the classification of attention-deficit hyperactivity disorder (ADHD) in an epidemiologically derived sample of primary school children. A monothetic schema (DSM-III) differed from a polythetic-only schema (DSM-III-R) by having a higher frequency of comorbid conduct disorder. A pervasive model was too restrictive, identifying only the most severe disruptive or conduct disordered children. Raising the minimum threshold above eight symptoms (DSM-III-R) missed less disruptive children who nevertheless exhibit significant functional impairment. There was minimal support for the independence of a syndrome of attention deficit disorder without hyperactivity (DSM-III). Finally, ADHD patients commonly have other diagnoses, most frequently conduct disorder, oppositional defiant disorder, and anxiety disorder.