Personality traits among individuals who as adolescents consulted for a substance use problem

Background: Adolescent antisocial behavior including substance misuse is associated with negative consequences both for the individual and the society, for example school drop-out, and high costs in the criminal justice and health systems. Further understanding of adolescent substance misuse is needed to inform treatment programs. The main aim of this thesis is to advance understanding of personality traits, and most particularly psychopathic traits, among adolescents engaging in substance misuse. Knowledge of these traits, their associations with current and future psychopathology and antisocial and criminal behavior, and their stability as adolescents’ transition to adulthood, is needed to further understanding of the development of substance use disorders and to inform interventions designed to reduce substance misuse. Method: Data were used from a follow-up study of 180 adolescents (99 women and 81 men) who contacted a substance use clinic in 2007 during a 7-month period. Data were analysed from the initial assessment and two follow-ups, 12 months, and five years after inclusion in the study. Results: Four main findings emerged: (1) Two measures of personality, the HP5i and the JTCI presented adequate validity when used among adolescents seeking treatment for a substance use problem. Individuals with externalizing symptoms rated themselves as more impulsive, quick-tempered, and easily board while individuals with internalizing symptoms rated themselves as presenting higher levels of negative feelings. (2) Concurrent and longitudinal associations between psychopathic traits and symptoms of mental disorders among adolescents who sought treatment for substance misuse. There were positive associations between psychopathic traits and externalizing symptoms. Elevated levels of psychopathic traits and conduct disorder is a combination of conditions with negative prognosis, findings of the present thesis suggest that oppositional deviant disorder are equally important to assess in girls with high levels of psychopathic traits. Among boys, there was a positive association between psychopathic traits and internalizing symptoms. Lack of negative emotions is a problem among individuals with high levels of psychopathic traits and coping with negative emotions challenging for individuals with internalizing symptoms. (3) There was stability in psychopathic traits from mid-adolescence to early adulthood. Individuals with a high PCL-R score (20-40) at the five-years-follow-up showed the greatest stability. (4) There were few factors associated with change in psychopathic traits and scores of psychopathic traits predicted mental health, psychosocial functioning and antisocial/criminal behaviours five years later. Conclusion: In treatment of individuals presenting externalizing problems the trait impulsivity will be important to consider while for those presenting internalizing problems negative emotions will need to be targeted for treatment success. Co-occurring mental disorders among individuals with high levels of psychopathic traits are important to assess as they may characterize subgroups with antisocial behaviour. Adolescent substance misuse treatment programs may benefit from identifying clients presenting high levels of psychopathic traits and providing them with specific interventions that take account of their personality.