Attention-deficit hyperactivity disorder subtypes and comorbid disruptive behaviour disorders in a child and adolescent mental health clinic.

Abstract

To assess demographic characteristics and patterns of comorbid disruptive behavior disorders (oppositional defiant disorder [ODD] or conduct disorder [CD]) in subtypes of attention-deficit hyperactivity disorder (ADHD). One hundred youths consecutively referred to a community child and adolescent mental health clinic and subsequently diagnosed with ADHD by the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria were evaluated. The diagnosis was made by a child psychiatrist and was based on information from physicians, parents, teachers, and diagnostic interviews with the youth and their parents. The major findings were: 1) ADHD combined (C) type was diagnosed in 78% of the subjects, while 15% had inattentive (1) type and 7% had hyperactive-impulsive (HI) type; and 2) patterns of comorbid disruptive behavioural disorders significantly differed among subtypes. Specifically, subjects with the I type showed lower rates of comorbid ODD than those with the C type (33% and 85%; P < 0.001) and HI type (33% and 100%; P = 0.005); subjects with the HI type displayed a higher prevalence of CD than those with the I type (57% and 0%; P = 0.005) and C type (57% and 8%; P = 0.003). These results should be considered tentative because the reliability of the diagnostic procedures was not formally assessed and the number of subjects in the I and HI groups was small. ADHD subtypes showed significant differences in the distribution of comorbid disruptive behaviour disorders. These results support the utility of ADHD subtypes but should be replicated with a larger sample of I and HI type subjects using more rigorous diagnostic methods.