Absence of iatrogenic or contagion effects in adolescent group therapy: findings from the Cannabis Youth Treatment (CYT) study.

Though widely used and presumed effective in practice, some scholars (Dishion et al., 1999) have raised the concern that group therapy for adolescents with substance use disorder and a range of deviancy has the potential for causing iatrogenic effects (e.g., increased substance use, behavior and legal problems) for those with low deviancy. Using data from 400 youth in the largest adolescent treatment experiment conducted to date (Dennis et al., 2004), this study shows that group composition in terms of conduct disorder symptoms is not associated with worse substance use, psychological, environmental or legal treatment outcomes. The results actually indicated that there was a slight advantage for youth with high conduct disorder to be included in the groups with less symptoms. The results appear consistent with recent meta-analyses of delinquency studies (Lipsey, 2006) which have found no evidence of iatrogenic effects. These results support the common clinical belief that group therapy for youths with substance use disorders is a safe and effective treatment modality.