Diagnosis of a conduct disorder may begin when parents bring a child to a family physician after the child has displayed particularly unruly behavior. Oftentimes, the referral occurs in response to a threatened or actual suspension from school. The physician will likely try to rule out any physical illness by performing a complete physical examination and compiling a thorough medical history.

If the physician suspects a conduct disorder or another psychological problem, the child will likely be referred to a mental health professional, such as a child and adolescent psychiatrist or psychologist. This expert will assess the patient’s motor, cognitive, academic and social competencies, as well as examine  the child’s behavior in school, with peers, at home with family members, and in relation to the community. In addition, certain standard tests or other psychological assessment tools may be used. Urine and blood analyses may be ordered to reveal abused substances. The patient and family members will also likely be interviewed about any unusual behaviors.

Diagnosing conduct disorders can be difficult. Patients may withhold information about poor behaviors. Although the mental health professional may also interview caregivers or others to get a more subjective view of the child’s behavior, this information may be limited. Patients with conduct disorders may conceal their worst behavior from loved ones.

Conduct disorders are diagnosed in patients who display a repetitive and persistent pattern of behavior that violates the rights of others or transgresses major age-appropriate societal norms or rules. This behavior must cause significant difficulty in social, academic or occupational functioning.

In addition, three or more of the following criteria must be present within a 12-month period, and at least one criterion must be present within the past six months:

• Aggression toward people and animals. Bullying, threats or intimidation of others, including starting fights and using weapons that can harm others (e.g., guns, bats, broken bottles). These patients may be physically cruel to animals or humans, or may have stolen items when confronting a victim (e.g., mugging) or sexually assaulted another person.
  
  
• Destruction of property. Deliberately destroying another person’s property such as by setting it on fire. It also can include other types of behavior intended to destroy property such as vandalism.
  
  
• Deceitfulness or theft. Examples include breaking into someone’s house, building or car; lying to obtain goods or favors or to avoid obligations; and stealing items of value without confronting the victim (e.g., forgery, shoplifting).
  
  
• Serious violation of rules. Examples include staying out all night in defiance of parent’s orders, running away from home overnight more than twice while living in the caregiver’s home and repeatedly skipping school without permission.