Behavioral and developmental disorders among conduct disorder.

The purpose of the present study was to clarify the percentage of children with conduct disorder (CD) who also have behavioral and developmental disorders. A survey of comorbidity observed in children with CD, was carried out on 33 subjects from a disciplinary facility for children. Female teachers as the mother were interviewed as regards the subjects' condition using the semistructured interview, and male teachers as the father were interviewed for their psychosocial problems. The subjects underwent the Wechsler Intelligence Scale for Children (WISC)-III and their conditions were diagnosed according to Diagnostic and Statistical Manual of Mental Disorders (4th edn; DSM-IV). Of the 33 children, 27 were diagnosed as having CD. Of the 27 CD children, 18 (67%) were diagnosed as having attention deficit hyperactivity disorder (ADHD), and 19 (70%) had oppositional defiant feature (ODF). Eight children (30%) were diagnosed as having mental retardation and in seven children (26%), the verbal IQ was significantly lower than the performance IQ. Two (7%) were diagnosed as having pervasive developmental disorders (PDD). Of 27 children diagnosed with CD, 23 (85%) had some behavioral and developmental disorders. The classification of these behavioral and developmental disorders into the following three types appeared to be clinically useful: type 1, ADHD and ODF; type 2, low intelligence, especially low verbal intelligence; and type 3, PDD. To understand and treat children with CD, the accurate diagnosis of these underlying behavioral and developmental disorders is indispensable.