Fleming, Blum, and Grant, 1989a; Velez, Johnson, and Cohen, 1989; Bird, Canino, Rubio-Stipec, Gould, Ribera, Sesman et al., 1988; Anderson, Williams, McGee, and Silva, 1987; Offord, Boyle, Szatmari, Rae Grant, Links, Cadman et al., 1987). The costs to society of having such a high prevalence are not known, but obviously they are high, for they include the costs of damage to other people's property, the costs of educational, legal, and social service interventions, and the costs of loss of potential and eventual productivity of these individuals. Conduct disorder is not easily treated. Although many treatments are being applied and some, including problem-solving skills training, parent management training, and functional family therapy, have achieved positive short-term outcomes (Kazdin, 1993), the long-term success of these interventions is not known.
Symptoms of conduct disorder may arise from many different pathways. Loeber and colleagues (Loeber, Wung, Keenan, Giroux, Stouthamer-Loeber, Van Kammen, and Maughan, 1993) have postulated three routes: (1) an aggressive-versatile route with early onset, with symptoms that are already severe in preschool; (2) a nonaggressive, antisocial pathway with onset in late childhood to early adolescence, with conduct problems but no hyperactivity or aggression; and (3) an exclusive substance abuse pathway with onset in middle to late adolescence. There is a marked difference between the early-onset form of conduct disorder in a temperamentally difficult child who has accompanying attention deficit disorder and learning difficulties, and the late-onset form appearing in an adolescent who has previously functioned well but who in response to environmental stress suddenly changes patterns of behavior. Robins's (1980) work has suggested that late-onset conduct disorder is typically predated by early experimentation with sex, drugs, and alcohol. Adolescents who are most likely to be chronically antisocial are those who show early-onset, pervasive disorder, and co-occurrence of early hyperactivity (White, Moffitt, Earls, Robins, and Silva, 1990).
Within the DSM classification system, a majority of children with conduct disorder also have other concomitant psychiatric diagnoses. Conduct disorder often occurs in tandem with attention deficit disorder. Forty percent of children with attention deficit disorder go on to develop symptoms of conduct disorder (Offord, Boyle, Racine, Fleming, Cadman, Blum et al., 1992). The salient difference between those who remain attention deficit disordered but do not develop conduct disorder may lie in the level of family functioning. Families who provide a supportive, consistent environment with clearly defined limits presumably allow these children to develop enough social skills that they can