Conduct Disorder

Conduct disorder (CD) is a repetitive and persistent pattern of behavior that violates the rights of others or age-appropriate norms and causes significant impairments in various domains of functioning. CD accounts for a substantial number of youths who enter into mental health facilities in the United States and Canada, and for this reason it is an important disorder for researchers to investigate and for clinicians to treat. Although CD continues to be problematic for the individual and society, remarkable progress has been made in our understanding of CD. Subtyping approaches have helped reduce some of the heterogeneity of the disorder and provide a better understanding of the potential etiologies associated with various types of CD. In addition, intervention programs have been developed that have been shown to be effective. These treatment programs tend to be intensive and multimodal, focusing on working with the youth to reduce CD symptoms but also providing parent training to improve attachment as well as parental monitoring and supervision practices. It is hoped that future research focusing on further refining the subtypes of CD and determining interventions that are most effective with specific subtypes of youth will assist mental health professionals in reducing CD symptoms and the concomitant costs to society.

Conduct Disorder Definition and Subtypes

According to the Diagnostic and Statistical Manual of Mental Disorders (fourth edition, text revision; DSM-IV-TR), CD is a repetitive and persistent pattern of behavior that violates others’ rights or age-appropriate norms and causes clinically significant impairments in various domains of functioning. For example, symptoms of CD may include aggression, damaging property, and lying. For a diagnosis of CD, the youth must have evidenced 3 of the 15 symptoms within the past 12 months, with at least 1 symptom being present for the past 6 months.

Because youths with CD are a heterogeneous group, various attempts have been made to identify subtypes of CD for informing etiology and intervention strategies. Earlier versions of the DSM differentiated between socialized versus undersocialized and aggressive versus nonaggressive dimensions. The socialized subtype was characterized by covert and overt antisocial behavior committed within the context of groups, whereas the undersocialized subtype was characterized by assaultive behavior that was carried out alone.

The current version of the DSM in part incorporates Terrie Moffitt’s taxonomy and differentiates subtypes based on the age of onset: The childhood-onset and adolescence-onset subtypes are defined by characteristics of the disorder being present before and after the age of 10, respectively. This classification is intended to distinguish the life-course-persistent antisocial youth from the adolescence-limited antisocial youth, a potentially less serious subtype of CD. In support of this distinction, research by Paul Frick and Jeffrey Burke and colleagues has found that childhood-onset CD is associated with temperament and family dysfunction, whereas adolescence-onset CD is associated with delinquent peer affiliation. Furthermore, early onset is associated with the persistence of CD and an increased likelihood of violent and criminal behavior.

Two other classification systems include differentiating CD into overt and covert subtypes and on the basis of two common co-occurring disorders, attention deficit hyperactivity disorder (ADHD) and anxiety. Research by Jeffrey Burke and colleagues and Paul Frick and colleagues suggests that there is some evidence for the utility of these distinctions. The presence of covert symptoms is associated with the persistence of CD, and youths with both CD and ADHD engage in a greater variety of delinquent behaviors and are more violent. In contrast, youths with both CD and anxiety display fewer impairments in peer relationships and have fewer police contacts.

Conduct Disorder Prevalence and Impact

According to the DSM-IV-TR, the prevalence of CD ranges from 1% to more than 10% in the general population. Large-scale population studies report prevalence rates ranging from 3% to 10% in nonclinical samples. Prevalence rates by gender are reported to range from 2% to 16% in boys and 1% to 9% in girls. The differences in prevalence rates are likely due to differences in the age of the youths sampled, CD criteria, time frame, and method of assessment.

The negative consequences associated with CD affect a variety of domains, including education (e.g., poor academic performance), employment (e.g., increased likelihood of the need for financial assistance), relationships (e.g., peer rejection), mental health (e.g., substance abuse), and criminality. Second, a diagnosis of CD can increase one’s risk for other psychiatric and emotional disorders. The most well-established outcome is the link between CD and antisocial personality disorder (APD) in adulthood, on the assumption that there is a developmental progression between the disorders. Research by Lee Robins sug-gests that between 25% and 40% of children with CD will meet the diagnostic criteria for APD.

Finally, CD is one of the most costly diagnoses in terms of involvement with mental health services and the criminal justice system. Youths with CD use a variety of services, including additional school resources, social services, general health services, inpatient and outpatient mental health services, and juvenile justice services. Research by Michael Foster and Damon Jones indicates that the cost of services used by the average youth with CD exceeds $14,000 per youth by the end of adolescence and the cost of total expenditures across adolescence is approximately $70,000 more than for youths without any behavioral disorders. Research by Stephen Scott and colleagues indicates, in more general terms, that children with CD cost 10 times more than those without CD.

Conduct Disorder and Psychopathy

Research by Paul Frick and Donald Lynam suggests that psychopathy and a callous and unemotional interpersonal style may identify a subtype of childhood-onset CD. More important, the presence of callous-unemotional traits may provide the necessary developmental link between CD and psychopathy. Cross-sectional studies have found that antisocial youths with callous-unemotional traits exhibit a greater number, variety, and severity of conduct problems and more severe forms of aggression. Children with CD and callous-unemotional traits also evidence a preference for thrill-seeking activities, possess a reward-dominant response style, and demonstrate less anxiety. Further support for this distinction is the finding that genetic factors appear to play a larger role in those with callous-unemotional traits. Finally, callous-unemotional traits are predictive of a number of negative outcomes, including a greater number and variety of conduct problems, higher levels of proactive aggression and self-reported delinquency, more police contacts, and a diagnosis of APD in adulthood.

Conduct Disorder Prevention and Intervention

CD is typically regarded as a disorder that is not very amenable to treatment efforts. In fact, earlier research suggested that the majority of early treatment efforts have been found to be largely ineffective. Second, treatment of CD is difficult owing to noncompliance. Finally, certain interventions, such as peer group strategies, can have iatrogenic effects and increase the level and severity of antisocial behavior. Despite these generally negative early findings with respect to the treatment of CD, a number of interventions have been found to be effective, including medication and various psychosocial treatments.

For very severe cases of CD, some have suggested that psychopharmacology may be indicated. Jeffrey Burke and colleagues suggest that drugs such as lithium, risperidone, and methylphenidate may be effective for youths with severe CD. More specifically, LeAdelle Phelps and colleagues suggest that haloperidol, clonidine, methylphenidate, and risperidone may be effective in reducing severe aggression in youths with CD. However, psychopharmacology is not recommended as the primary treatment for CD because there is a lack of evidence that medication can alter the symptoms of CD per se and the medications do not have a prophylactic effect on CD symptoms. Rather, it appears that medication is most effective in reducing severe conduct problems in difficult cases. Although we note these recommendations for severe CD, we do so with caution given the lack of sound methodological studies on the effectiveness of psychopharmacological treatments for youths with CD. Mental health professionals should carefully weigh the costs and benefits of administering drugs in the treatment of CD.

A number of effective behavioral and psychosocial interventions for treating CD have been reviewed by Alan Kazdin and Paul Frick. One of the most effective interventions is parent management training (PMT). The focus of PMT is to reduce problem behaviors and increase prosocial behaviors by educating parents in techniques such as positive reinforcement, consistent discipline, and effective supervision. There is evidence suggesting that PMT is effective in the short term in clinical populations, reduces deviant behavior across multiple domains, and is able to reduce problematic behaviors to within the levels of normative youth, with benefits evident 1 to 3 years after treatment. Similarly, intervention strategies that use appropriate parenting strategies and attachment principles have also proved effective in terms of decreasing externalizing and internalizing problems in adolescents with CD. However, it can be difficult to motivate parents to complete treatment programs, and there is evidence that parent training is not always effective with severely dysfunctional families.

Another effective treatment strategy adopts a cognitive-behavioral approach, which targets deficits in social cognition and problem solving, largely through inhibiting impulsive or angry responding by altering the processing of social information. A variant of this approach is child social skills training, which focuses on addressing interpersonal problems through techniques such as anger control and coping skills. There is some evidence for the effectiveness of social skills training in terms of decreases in aggression and antisocial behavior, increases in prosocial behavior in the short term, and improved interactions with peers. However, it can be difficult to maintain the skills over long periods and in domains outside the therapeutic setting. Therefore, some researchers recommend booster sessions to maintain the effects of treatment.

A promising approach is that of multimodal interventions such as multisystemic therapy (MST), which addresses risk at the individual, family, peer, school, and neighborhood levels. MST involves a comprehensive assessment to determine how the various levels influence the youth’s problem behavior, and this information is then used to develop an individualized, intensive treatment plan. For example, parents may be educated in how to improve communication, and youths may be encouraged to increase their association with prosocial peers. There is some evidence of the effectiveness of MST in terms of reduction in aggressive behavior, lower rearrest rates, and fewer days of incarceration, with the benefits maintained for as long as 5 years posttreatment.

As noted by Paul Frick and Eva Kimonis, the general conclusions regarding intervention for CD are that treatment is more effective with younger children, who exhibit less severe conduct problems; treatment effects do not generalize across settings; and it is difficult to sustain improvements over time. Bearing in mind these concerns, future efforts should be directed toward determining which treatments are the most effective at different developmental stages and for specific subtypes of youth.

In addition to developing and administering appropriate intervention strategies, efforts should also be directed toward the prevention of CD symptoms. Interventions focus on mental illness with the goal of reducing or ameliorating impairment, whereas prevention focuses on mental health with the goal of developing adaptive, prosocial functioning. Generally, prevention programs do not address CD directly but address the risk factors related to CD and target youths identified as being at high risk for developing CD. Promising prevention programs include early family-based interventions that provide support and services to women during and after pregnancy, school-based interventions that provide additional intensive classroom programs, and community-based interventions that provide programs and activities in the community to promote prosocial behavior. Some examples include the Triple-P positive parenting program, the Fast Track program, and the Incredible Years parenting program. Follow-up studies with youths who received these types of interventions found that they resulted in less aggression, fewer acting-out behaviors, lower arrest and recidivism rates, and less severe criminal offenses.


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