Conduct Disorder

Conduct Disorder is a mental disorder characterized by a repetitive and persistent pattern of behaviour in which the basic rights of others or major age-appropriate societal norms or rules are violated. These behaviours fall into four main categories: aggressive conduct that causes or threatens physical harm to other people or animals, non-aggressive conduct that causes property loss or damage, deceitfulness or theft, and serious violations of rules.

• In the United States, the 1-year population prevalence ranges from 2 to 10% (average 4%)^[1]
• Prevalence rates increase from childhood to adolescence
• Conduct disorder is more common among males than among females.^[2]

• The onset of conduct disorder may start as early as the preschool years, but the significant symptoms usually begin during middle childhood to middle adolescence.^[3]
  • Behaviours may lead to school suspension/expulsion, problems at work, legal difficulties, unplanned pregnancy, sexually transmitted diseases, and injuries from accidents/fights.
• Oppositional defiant disorder is a common precursor to childhood-onset type of conduct disorder.
• Approximately 40% of children and adolescents with conduct disorder may become adults with antisocial personality disorder.^[4]
  • Once someone qualifies for the diagnosis of antisocial personality disorder, they no longer have conduct disorder.
• Individuals very commonly come into contact with the criminal justice system for engaging in illegal behavior, and it is frequently diagnosed in mental health facilities for children (especially in forensic practice).
• The course of conduct disorder is quite variable, however. In the majority of individuals, the disorder actually remits by adulthood.^[5]
  • The risk that conduct disorder will persist into adulthood is increased by the presence of comorbid attention-deficit/hyperactivity disorder (ADHD) and substance use disorders.
• Those with lower severity and fewer symptoms are able to achieve adequate social and occupational adjustment as adults.^[6]
• Although conduct disorder can be diagnosed in adults, symptoms usually already emerge in childhood or adolescence. Thus, onset is quite rare after age 16.^[7]
• Gender differences also exist between males and females:
  • Males often have fighting, stealing, vandalism, and school discipline problems.
  • Females are more likely to have lying, truancy, running away, substance use, and prostitution.
  • While males exhibit both physical and relational aggression (behaviour that harms social relationships with others), females tend to exhibit only relational aggression.^[8]

• Individuals are more likely to have specific learning disorder, lower intelligence, ADHD, mood disorders, anxiety disorders, posttraumatic stress disorder (PTSD), psychotic disorders, somatic symptom disorders, impulse-control disorders, and substance-related disorders as adults.
• Substance use disorders is common, particularly in adolescent females.^[9]
• Suicidal ideation, suicide attempts, and completed suicide are also higher.^[10]

• It is more common in children of biological parents with severe alcohol use disorder, depressive disorders, bipolar disorders, schizophrenia, ADHD, and conduct disorder.^[11]
• Temperamental risk factors include a difficult infant temperament and low intelligence (most associated with low verbal IQ).^[12]
• Adverse childhood events such as parental rejection and neglect, inconsistent parenting, physical or sexual abuse, lack of supervision, early institutional living, frequent loss of caregivers, large family sizes, parental criminality, and familial substance use disorders are risk factors.
• Peer rejection, association with a delinquent peer groups, and neighbourhood exposure to violence are societal and environmental risk factors.^[13]

A repetitive and persistent pattern of behavior in which the basic rights of others or major age-appropriate societal norms or rules are violated, as manifested by the presence of at least 3 of the following 15 criteria in the past 12 months from any of the categories below, with at least 1 criterion present in the past 6 months:

The disturbance in behaviour causes clinically significant impairment in social, academic, or occupational functioning.

If the individual is age 18 years or older, criteria are not met for antisocial personality disorder.

• Conduct disorder is divided into 3 subtypes (childhood-onset, adolescent-onset, and unspecified), based on the age at onset of the disorder.
  • In childhood-onset, individuals are usually male, have physical aggression toward others, disturbed peer relationships, may have had oppositional defiant disorder during early childhood.^[14]
    • The severity of behaviours is such that the full criteria for conduct disorder is usually met prior to puberty.
    • Childhood-onset is predominated by males.^[15]
  • Many children with this subtype also have concurrent attention-deficit/hyperactivity disorder (ADHD) or other neurodevelopmental difficulties.
  • The prognosis is also worse for these individuals, as they are likely to have persistent conduct disorder into adulthood (compared to those with adolescent-onset type).
  • Individuals with adolescent-onset are less likely to have aggressive behaviors and tend to have more normative peer relationships. These individuals are less likely to have conduct disorder that persists into adulthood.
    • The ratio of males to females is also more balanced.

• Conduct Disorder Scale (CDS)

• Slower resting heart rate has interestingly and reliably been noted in individuals with conduct disorder, and this biomarker is not characteristic of any other mental disorder.^[16]
  • Reduced autonomic fear conditioning, particularly low skin conductance, is also well documented.

• Neuroanatomical differences in affect regulation and processing, particularly frontotemporal-limbic connections involving the ventral prefrontal cortex and amygdala are seen in conduct disorder.
  • However, neuroimaging findings are not diagnostic for the disorder.

• Oppositional defiant disorder (ODD)
  • Conduct disorder and ODD are both related to symptoms that bring the individual in conflict with adults or authority figures (e.g. - parents, teachers, employers). The behaviours of ODD, however, are less severe than conduct disorder. It additionally does not include aggression toward individuals or animals, destruction of property, or a pattern of theft or deceit. ODD also includes difficulties with emotional dysregulation (i.e. - angry and irritable mood) that is not seen in conduct disorder. If criteria are met for both ODD and conduct disorder, then both diagnoses can be made.^[17]
• Attention-deficit/hyperactivity disorder (ADHD)
  • Although children with ADHD often exhibit hyperactive and impulsive behavior that may be disruptive, this behaviour does not by itself violate societal norms or the rights of others and therefore does not typically meet criteria for conduct disorder. If criteria are met for both ADHD and conduct disorder are met, then both diagnoses should be made.
• Depressive and bipolar disorders
  • Aggression, irritability, and conduct problems can occur in children or adolescents with major depressive disorder, bipolar disorder, or disruptive mood dysregulation disorder (DMDD). The behavioural issues in these mood disorders can be distinguished from conduct disorder based on the course of symptoms. In conduct disorder, there are substantial levels conduct problems during periods in which there is no mood disturbance. In cases where criteria for conduct disorder and a mood disorder are met, both diagnoses can be given.
• Intermittent explosive disorder (IED)
  • Both conduct disorder and IED involve severe aggression. However, in IED, this is limited to impulsive aggression, is not premeditated, and is not committed in order to achieve an objective (e.g. - money, power, intimidation). Also, IED does not include the non-aggressive symptoms of conduct disorder. If criteria for both disorders are met, the diagnosis of IED should be given only when the recurrent impulsive aggressive outbursts warrant independent clinical attention.
• Adjustment disorders
  • Adjustment disorder (plus specifier: with disturbance of conduct or with mixed disturbance of emotions and conduct) should be considered if clinically significant conduct problems develop in clear association with the onset of a psychosocial stressor and do not resolve within 6 months of the termination of the stressor (or its consequences). Conduct disorder is diagnosed only when the conduct problems represent a repetitive and persistent pattern that is associated with impairment in social, academic, or occupational functioning.

• In individuals with a suspected learning disability, psychoeducational testing may be important.

• Evidence-based psychosocial interventions with a psychiatrist, psychologist or therapist is an important part of long-term treatment.
• There are no pharmacotherapies to treat conduct disorder.
  • Treating any comorbid disorders, such as ADHD is important.