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Exposure to high levels of peer group deviance in childhood and adolescence is strongly associated with an increased risk for future antisocial behaviours. However, little has been known about characteristics of adolescents or their peers that enhance or diminish peer influence on antisocial behaviour.

The study by Kerr et al. (2012) examined adolescents’ (targets) and their peers’ psychopathic personality traits as moderators of peer influence on delinquency in peer networks. They used self-ratings of the three separate dimensions of the psychopathic personality (grandiose-manipulative, callous-unemotional and impulsive-irresponsible) and a peer network approach with five waves of longitudinal data. The longitudinal design allowed them to disentangle the effects of peer influence and selection, which is critical since prior studies of peer-group deviance have suggested bidirectional effects (i.e. individuals with delinquent tendencies selectively link with others like themselves and exposure to deviant peers may enhance these pre-existing tendencies). The longitudinal design also allowed the authors to document the temporal ordering of the study variables, which is essential for studies of moderating and mediating effects. The main results of Kerr et al. (2012) suggest that how much adolescents are influenced by their peers’ delinquency depends on both their peers’ and their own psychopathic personality traits. Thus, the higher adolescents are on psychopathic traits, the less they seem to be influenced by their peers’delinquency, but the more they seem to influence others.

Psychopathic personality is a relatively novel construct in child psychopathology research and the study by Kerr et al (2012) advances the knowledge about the childhood and adolescent manifestation of these traits. Psychopathic personality traits or psychopathy was for a long time mainly studied in adult criminal offender settings. This research demonstrated that psychopathy is a serious personality disorder associated with a particularly severe and violent pattern of antisocial behaviour. Psychopathy is still an important construct in adult forensic settings, but there has also been a substantial interest in the study of developmental aspects of this personality disorder, which has been necessary in order to identify potential precursors to adult psychopathy. The research on the downward extension of psychopathic personality traits to children and adolescent has generally been promising and the work by Kerr and colleagues represents an excellent example of how these traits can be used to improve the understanding of different developmental pathways to antisocial behaviours.

The study by Kerr et al. (2012) contributes to the growing body of research that highlights psychopathic traits as important moderators of the developmental course and etiology of antisocial behaviours. A large number of the prior studies have focused on the callous-unemotional (CU) dimension of psychopathic personality and overall these findings support the clinical utility of assessing CU traits in children presenting for conduct problems. Among many things, it has been demonstrated that antisocial children with elevated levels of CU traits show a particularly severe and stable pattern of antisocial behaviour, as well at-risk neurocognitive profiles, when compared to other children with conduct disorder. In response to this research, the DSM-V ADHD and Disruptive Behavior Disorders Work Group are now considering the utility of CU traits as a possible subtyping index or additional symptom dimension of conduct disorder (Moffitt et al., 2008).

The results of Kerr et al (2012) indicate that youth high on psychopathic traits are relatively insensitive to the influence of others. This finding extends prior studies showing that antisocial behaviours in children with CU traits is less strongly associated with poor parental practices (e.g., poor supervision and harsh and inconsistent discipline) than it is for children without these traits. The original hypothesis in this line of research was that for those high on callous-unemotional traits, antisocial behaviours originate with temperamental fearlessness and are relatively unaffected by poor parental socialization practices. That idea and the findings from Kerr et al (2012) are both consistent with twin research reporting that antisocial behaviour is more heritable among children with CU traits than among other children (Viding, Blair, Moffitt, & Plomin, 2005). However, it is important to note that the few prior studies on CU trait moderation of parenting effects were based on cross-section data, which constrains possibilities to isolate true moderation effects. Future studies should use longitudinal data to account for bidirectional effects and for reverse causation. It is also important to clarify that high heritability from twin studies does not imply that vulnerability to CU traits is deterministically set for life or that it is non-mutable. In fact, a straight forward prediction from twin study results of moderate heritability is that future research will identify environmental exposures of relevance for change in CU traits. Genetically sensitive design will hopefully be applied more extensively in this area of research as it allows for investigations of direct environmental effects (controlling for familial confounding) as well as gene-environmental interplay.

In line with prior research, the results form Kerr et al. (2012) suggest that CU (and grandiose-manipulative traits) traits should be studied as a moderating factor for conduct disorder treatment responses. Such treatment implications have only recently begun to be explored, but the existing data indicate an expected differential treatment response in antisocial youth with and without CU traits (Hawes & Dadds, 2005). Specifically, Hawes and Dadds (2005) reported that clinic-referred boys with conduct problems and elevated levels of CU traits were less responsive to a parenting intervention than boys with conduct problems who were low on CU traits. However, the differential treatment response was not consistently found across all phases of the treatment. That is, children with and without CU traits seemed to respond equally well to the intervention that focused on teaching parents methods of using positive reinforcement to encourage prosocial behaviour. In contrast, only the group without CU traits showed improvements in the second part of the intervention that focused on teaching parents more effective discipline strategies. Clearly, in line with recommendations from the DSM-5 working group, future research should continue to incorporate CU traits into intervention research. The results from Kerr et al (2012) indicate that future research also should consider the grandiose-manipulative dimension as a potentially important moderator in the development of antisocial behaviours. This is important as most prior research have focused primarily on the CU trait dimension of psychopathy.

Acknowledgement

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This commentary article was invited by the JCPP Editors and while it has been subject to editorial review, it has not been formally peer reviewed. The author has declared that he has no competing or potential conflicts of interest.

Correspondence to

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Henrik Larsson, Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, P.O. Box 281, SE-171 77 Stockholm, Sweden; Tel.: +46-8-524 82344; Email: henrik.larsson@ki.se

References

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  4. References