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Treatment of oppositional defiant and conduct problems in young Norwegian children

Results of a randomized controlled trial


The efficacy of the Incredible Years parent training and child therapy programs was examined in a randomized controlled study including 127 Norwegian children aged 4–8 years. Children diagnosed with oppositional defiant disorder (ODD) or conduct disorder (CD) were randomized to parent training (PT), parent training combined with child therapy (PT + CT), or a waiting-list control condition (WLC). Assessments were carried out at baseline, posttreatment and at a one-year follow-up using standardized measures and a semi-structured interview. Both active treatment conditions reduced child conduct problems posttreatment as opposed to the WLC, while differences between the two treatment conditions were small and nonsignificant. About two thirds of the treated children functioned within normal variation after treatment, and the same proportion no longer received an ODD diagnosis at the one-year follow-up. Parental use of positive strategies increased after treatment, and the use of harsh and inconsistent discipline decreased as did mother experience of stress. The outcome of this study emphasizes the importance of offering parent training to young children with severe conduct problems exhibited at home. The findings and usefulness of the Incredible Years program in the present Norwegian replication study further support and extend positive outcomes of previous controlled trials conducted primarily in Anglo-Saxon countries.

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Fig. 1



Parent training

PT + CT:

Parent training and child therapy


Waiting list control


Oppositional defiant disorder


Conduct disorder


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We greatly appreciate the generous financial support from the Social and Health Directorate, Oslo. The help and assistance of Per Rypdal, Odd Sverre Westbye, and Odd Fyhn in setting up the clinics, and the contribution of all therapists involved in the study in Trondheim and Tromsø is gratefully acknowledged. The authors also gratefully acknowledge the continuous help, support and encouragement from professor Carolyn Webster-Stratton who made this study possible.

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Correspondence to Bo Larsson.

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Larsson, B., Fossum, S., Clifford, G. et al. Treatment of oppositional defiant and conduct problems in young Norwegian children. Eur Child Adolesc Psychiatry 18, 42–52 (2009).

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  • oppositional defiant disorder
  • conduct disorder
  • parent training
  • child therapy
  • randomized controlled trial