of the age of onset. aside from the differences in neuroanatomy and activation patterns between youth with conduct disorder and controls, neurochemical profiles also vary between groups. individuals with conduct disorder are characterized as having reduced serotonin and cortisol levels (e.g., reduced hypothalamic-pituitary-adrenal (hpa) axis), as well as reduced autonomic nervous system (ans) functioning. these reductions are associated with the inability to regulate mood and impulsive behaviors, weakened signals of anxiety and fear, and decreased self-esteem. taken together, these findings may account for some of the variance in the psychological and behavioral patterns of youth with conduct disorder. intra-individual factors aside from findings related to neurological and neurochemical profiles of youth with conduct disorder, intraindividual factors such as genetics may also be relevant. having a sibling or parent with conduct disorder increases the likelihood of having the disorder, with a heritability rate of .53. there also tends to be a stronger genetic link for individuals with childhood-onset compared to adolescent onset. in addition, youth with conduct disorder also exhibit polymorphism in the monoamine oxidase a gene, low resting heart rates, and increased testosterone. family and peer influences elements of the family and social environment may also play a role in the development and maintenance of conduct disorder. for instance, antisocial behavior suggestive of conduct disorder is associated with single parent status, parental divorce, large family size, and the young age of mothers. however, these factors are difficult to tease apart from other demographic variables that are known to be linked with conduct disorder, including poverty and low socioeconomic status. family functioning and parent-child interactions also play a substantial role in childhood aggression and conduct disorder, with low levels of parental involvement, inadequate supervision, and unpredictable discipline practices reinforcing youth's defiant behaviors. peer influences have also been related to the development of antisocial behavior in youth, particularly peer rejection in childhood and association with deviant peers. peer rejection is not only a marker of a number of externalizing disorders, but also a contributing factor for the continuity of the disorders over time. hinshaw and lee (2003) also explain that association with deviant peers has been thought to influence the development of conduct disorder in two ways: 1) a “selection” process whereby youth with aggressive characteristics choose deviant friends, and 2) a “facilitation” process whereby deviant peer networks bolster patterns of antisocial behavior. in a separate study by bonin and colleagues, parenting programs were shown to positively affect child behavior and reduce costs to the public sector. wider contextual factors in addition to the individual and social factors associated with conduct disorder, research has highlighted the importance of environment and context in youth with antisocial behavior. however, it is important to note that these are not static factors, but rather transactional in nature (e.g., individuals are influenced by and also influence their environment). for instance, neighborhood safety and exposure to violence have been studied in conjunction with conduct disorder, but it is not simply the case that youth with aggressive tendencies reside in violent neighborhoods. transactional models propose that youth may resort to violence more often as a result of exposure to community violence, but their predisposition towards violence also contributes to neighborhood climate. diagnosis conduct disorder is classified in the fourth edition of diagnostic and statistical manual of mental disorders (dsm). it is diagnosed based on a prolonged pattern of antisocial behaviour such as serious violation of laws and social norms and rules in people younger than the age of 18. similar criteria are used in those over the age of 18 for the diagnosis of antisocial personality disorder. no proposed revisions for the main criteria of conduct disorder exist in the dsm-5; there is a recommendation by the work group to add an additional specifier for callous and unemotional traits. according to dsm-5 criteria for conduct disorder, there are four categories that could be present in the child's behavior: aggression to people and animals, destruction of property, deceitfulness or theft, and serious violation of rules. almost all adolescents who have a substance use disorder have conduct disorder-like traits, but after successful treatment of the substance use disorder, about half of these adolescents no longer display conduct disorder-like symptoms. therefore, it is important to exclude a substance-induced cause and instead address the substance use disorder prior to making a psychiatric diagnosis of conduct disorder. treatment first-line treatment is psychotherapy based on behavior modification and problem-solving skills. this treatment seeks to integrate individual, school, and family settings. parent-management training can also be helpful. no medications have been fda approved for conduct disorder, but risperidone (a second-generation antipsychotic) has the most evidence to support its use for aggression in children who have not responded to behavioral and psychosocial interventions. selective serotonin reuptake inhibitors (ssris) are also sometimes used to treat irritability in these patients. prognosis about 25-40% of youths diagnosed with conduct disorder qualify for a diagnosis of antisocial personality disorder when they reach adulthood. for those that do not develop aspd, most still exhibit social dysfunction in adult life. epidemiology conduct disorder is estimated to affect 51.1 million people globally as of 2013. the percentage of children affected by conduct disorder is estimated to range from 1-10%. however, among incarcerated youth or youth in juvenile detention facilities, rates of conduct disorder are between 23% and 87%. sex differences the majority of research on conduct disorder suggests that there are a significantly greater number of males than females with the diagnosis, with some reports demonstrating a threefold to fourfold difference in prevalence. however, this difference may be somewhat biased by the diagnostic criteria which focus on more overt behaviors, such as aggression and fighting, which are more often exhibited by males. females are more likely to be characterized by covert behaviors, such as stealing or running away. moreover, conduct disorder in females is linked to several negative outcomes, such as antisocial personality disorder and early pregnancy, suggesting that sex differences in disruptive behaviors need to be more fully understood. females are more responsive to peer pressure including feelings of guilt than males. racial differences research on racial or cultural differences on the prevalence or presentation of conduct disorder is limited. however, according to studies on american youth, it appears that african-american youth are more often diagnosed with conduct disorder, while asian-american youth are about one-third as likely to develop conduct disorder when compared to white american youth. it has been widely theorized for decades that this disparity is due to unconscious bias in those who give the diagnosis.