Do personality traits affect responsiveness of juvenile delinquents to treatment?

• Examining the moderating role of personality traits in MST effectiveness.
• A randomized controlled trial (N = 256) was used to examine the research questions.
• Effectiveness was largest for highly Conscientious, highly Agreeable juveniles.
• No long term moderating effects of personality traits were found.
• Extraversion, Emotional Stability or Openness did not moderate the effectiveness.

ObjectiveThe aim of the present study was to examine the moderating role of Big Five personality traits in short and long term effectiveness of MultiSystemic Therapy (MST) for serious and persistent juvenile delinquents.MethodData of a randomized controlled trial (N = 256) were used to examine the research question.ResultsExtraversion, Emotional Stability and Openness did not moderate short term effectiveness of MST, but Conscientiousness and Agreeableness did: MST was most effective for highly conscientious and highly agreeable juvenile delinquents. Personality did not moderate the effectiveness of MST on aggression or the long-term effectiveness of MST.ConclusionThis study shows the importance of personality traits for short-term treatment outcomes, effectiveness of MST differs for high/low Agreeableness and Conscientiousness.