This week on the blog Kara writes about conduct problems and the importance of identifying and understanding differing aetiologies and trajectories across through the lifespan.
The ability to negotiate complex social problems in a non-aggressive manner is central to the success of the human race. However, while everybody is prone to defiance or impulsivity at times, some individuals display difficult and challenging behaviours that go beyond the norm. When young people display these difficulties, we call them ‘conduct problems’.
‘Conduct problems’ is a broad term that describes a set of aggressive, antisocial and disruptive behaviours, such as extreme temper outbursts or telling lies. While estimates vary, up to 10% of children in the general population are reported to display clinically significant levels of conduct problems (Hinshaw & Lee, 2003). Given that conduct problems are the most common reason for child treatment referral (Loeber, Burke, Lahey, Winters & Zera, 2000), the severity of this issue cannot be over-emphasised.
“‘Conduct problems’ is a broad term that describes a set of aggressive, antisocial and disruptive behaviours, such as extreme temper outbursts or telling lies. “
Overwhelmingly, we see that the seeds of conduct problems are sown very early in development, dramatically increasing in severity and prevalence by adolescence. Does this mean that young people ‘grow out’ of these behaviours by adulthood? Unfortunately, findings from longitudinal studies have found that even beyond childhood, these problems persist. Later outcomes associated with early conduct problems include decreased life opportunities in education, employment and earnings (Colman et al., 2009; Wertz et al., 2018), as well as increased susceptibility to psychiatric disorders (Johnson et al., 2015).
Developmental trajectories
It must be noted that individuals who display conduct problems are an extremely heterogeneous group. Although antisocial adults virtually always begin as children with conduct problems, most young people who engage in antisocial misconduct do not grow up to be antisocial adults (Martinez, Lee, Eck & SooHyun, 2017). Along with the strong stability over time and concentration of problems in adolescence, this was a difficult developmental puzzle to solve. Twenty-five years ago, Terrie Moffitt developed a taxonomy which reconciled these phenomena, proposing that individuals displaying conduct problems follow either a life-course persistent or adolescence-limited path.
“Most young people who engage in antisocial misconduct do not grow up to be antisocial adults.”
Individuals who follow an early onset persistent or life-course persistent trajectory start displaying challenging behaviours early in life which continue into adulthood. Those following an adolescence-limited trajectory do not have a history of childhood conduct problems prior to their teenage years. A further childhood-limited pathway was later included in the taxonomy. The taxonomy has stood the test of time, with more than 100 longitudinal studies confirming the existence of these trajectory groups (Moffitt, 2018).
A recent meta-analysis found that individuals following the early onset persistent pathway show significantly higher risks of poor outcomes across 13 measures, including substance use and poor education (Bevilacqua, Hale, Barker & Viner, 2017). The finding that there are poorer outcomes for those with the most severe symptoms has been widely replicated, but research about the adolescence-limited trajectory is not so clear-cut. There is now substantial evidence that a ‘maturity gap’ (i.e. a discrepancy between biological and social maturation), can explain remission from antisocial behaviour by adulthood (e.g. Barnes & Beaver, 2010). However, whether there is complete remission is under debate. For example, research from a large, population-based study found that individuals following this pathway were delayed in their recovery beyond anticipation (Odgers et al., 2007).
Genetic and environmental influences
Like most complex traits, an intricate interplay of biological and environmental factors underlies conduct problems. Twin studies have estimated heritability to be between 32-60% for children and 45-50% for adolescents (Burt, 2009; Rhee & Waldman, 2002). However, these estimates differ greatly from DNA-based SNP heritability estimates, which are generally low and non-significant, perhaps owing to small sample sizes. To date, a very small number of genome-wide association studies have been identified for conduct problems (Trzaskowski, Dale & Plomin, 2013).
Further insight into the genetic basis of conduct problems will be critical to planning and implementing effective interventions. It has been suggested that, because of the stability of conduct problems over time, current heritability estimates can be improved by using longitudinal data, collected from multiple raters. Indeed, preliminary results from research into both emotional and behavioural difficulties have found this to be the case; that focusing on a phenotype that captures stability across time rather than at individual ages significantly improves both twin and SNP heritability estimates.
“Like most complex traits, an intricate interplay of biological and environmental factors underlies conduct problems.”
While twin heritability estimates emphasise the role that genetics play in conduct problems, they also highlight the role of the environment. Environmental factors such as poverty, maltreatment and neglect have all been associated with the development of conduct problems (Hinshaw & Lee, 2003). It is also likely that genetic and environmental risk factors interact so studying either in isolation will be less useful than studies that combine the two.
Individuals who go on to offending careers and/or antisocial behaviour as adults are often dismissed as nuisances to society. However, it is important to bear in mind that externalising
behaviours are often manifestations of emotional difficulties that may begin very early in life. To maximise desistance from a lifetime of antisocial behaviour, we must intervene as early as possible. A more comprehensive understanding of the genetic and environmental risk factors at play will be invaluable in the development of appropriate interventions.
References
Barnes, J. C., & Beaver, K. M. (2010). An empirical examination of adolescence-limited offending: A direct test of Moffitt’s maturity gap thesis. Journal of Criminal Justice, 38(6), 1176-1185.
Bevilacqua, L., Hale, D., Barker, E. D., & Viner, R. (2017). Conduct problems trajectories and psychosocial outcomes in early adulthood: A systematic review and meta-analysis. European Child & Adolescent Psychiatry, 1-22. doi: 10.1007/s00787-017-1053-4
Burt, S. A. (2009). Are there meaningful etiological differences within antisocial behaviour? Results of a meta-analysis. Clinical Psychology Review, 29(2), 163-178.
Colman, I., Murray, J., Abbott, R. A., Maughan, B., Kuh, D., Croudace, T. J., & Jones, P. B. (2009). Outcomes of conduct problems in adolescence: 40 year follow-up of national cohort. British Medical Journal, 338, a2981.
Hinshaw, S. P., & Lee, S. S. (2003). Conduct and oppositional defiant disorders. Child Psychopathology, 2(1), 144-198.
Johnson, V. A., Kemp, A. H., Heard, R., Lennings, C. J., & Hickie, I. B. (2015). Childhood-versus adolescent-onset antisocial youth with conduct disorder: psychiatric illness, neuropsychological and psychosocial function. PloS One, 10(4), e0121627.
Loeber, R., Burke, J. D., Lahey, B. B., Winters, A., & Zera, M. (2000). Oppositional defiant and conduct disorder: a review of the past 10 years, part I. Journal of the American Academy of Child & Adolescent Psychiatry, 39(12), 1468-1484.
Martinez, N. N., Lee, Y., Eck, J. E., & SooHyun, O. (2017). Ravenous wolves revisited: A systematic review of offending concentration. Crime Science, 6(1), 10.
Moffitt, T. E. (2018). Male antisocial behaviour in adolescence and beyond. Nature Human Behaviour, 1.
Odgers, C. L., Caspi, A., Broadbent, J. M., Dickson, N., Hancox, R. J., Harrington, H., … & Moffitt, T. E. (2007). Prediction of differential adult health burden by conduct problem subtypes in males. Archives of General Psychiatry, 64(4), 476-484.
Rhee, S. H., & Waldman, I. D. (2002). Genetic and environmental influences on antisocial behaviour: a meta-analysis of twin and adoption studies. Psychological Bulletin, 128(3), 490.
Trzaskowski, M., Dale, P. S., & Plomin, R. (2013). No genetic influence for childhood behaviour problems from DNA analysis. Journal of the American Academy of Child & Adolescent Psychiatry, 52(10), 1048-1056.
Wertz, J., Agnew-Blais, J., Caspi, A., Danese, A., Fisher, H. L., Goldman-Mellor, S., … & Arseneault, L. (2018). From childhood conduct problems to poor functioning at age 18 Years: examining explanations in a longitudinal cohort study. Journal of the American Academy of Child & Adolescent Psychiatry, 57(1), 54-60.
