Conduct and oppositional disorders

[Extract] Conduct problems (CPs) in youth have been a major focus of research and practice in child psychology for a number of reasons. First, serious and impairing CPs are relatively common in children and adolescents, with meta-analyses of epidemiological studies showing rates between 3 and 4% worldwide for children and adolescents ages 6–18 years old (Canino, Plancyz, Bauermeister, Rohde, & Frick, 2010). However, this prevalence rate varies across boys and girls, especially after early childhood; that is, boys and girls show very similar rates of CPs before age 5, but this changes to a 3:1 ratio, with boys showing higher prevalence of CPs in later childhood. In adolescence, girls tend to show increases in CPs, closing the gap to a 2:1 male:female ratio (Frick, 2016). Second, CPs are some of the most common reasons for referral to mental health services in children and adolescents (Kazdin, Whitley, & Marciano, 2006; Kimonis, Frick, & McMahon, 2014), likely due to the fact that CPs can place a child at risk for peer rejection and school suspension or expulsion (Dodge & Pettit, 2003; Frick, 2012), as well as involvement with the legal system (Frick, Stickle, Dandreaux, Farrell, & Kimonis, 2005). As a result, the CPs prevalence rates in clinic-referred children range from 60 to 70% (Freeman, Youngstrom, Youngstrom, & Findling, 2016) and from 80 to 90% in incarcerated samples (Karnik et al., 2009; Livanou, Furtado, Winsper, Silvester, & Singh, 2019). Third, CPs may also have effects beyond childhood and adolescence, with research suggesting that CPs in childhood predict mental health (e.g., substance use), legal (e.g., being arrested), occupational (e.g., poor job performance), social (e.g., poor marital adjustment), and physical health (e.g., poor respiration) problems in adulthood (Odgers et al., 2007, 2008).