Editing Conduct disorder (section)

==Cause==
While the cause of conduct disorder is complicated by an intricate interplay of biological and environmental factors, identifying underlying mechanisms is crucial for obtaining accurate assessment and implementing effective treatment.<ref>Murrihy, R., Kidman, A., & Ollendick, T (2010). ''Clinical Handbook of Assessing and Treating Conduct Problems in Youth''. Springer: New York.</ref> These mechanisms serve as the fundamental building blocks on which evidence-based treatments are developed. Despite the complexities, several domains have been implicated in the development of conduct disorder including cognitive variables, neurological factors, intraindividual factors, familial and peer influences, and wider contextual factors.<ref name="Hinshaw" /> These factors may also vary based on the age of onset, with different variables related to early (e.g., neurodevelopmental basis) and adolescent (e.g., social/peer relationships) onset.<ref name="Passa">{{cite journal |author1=Passamonti L. |author2=Fairchild G. |author3=Goodyer I. |author4=Hurford G. |author5=Hagan C. |author6=Rowe J. |author7=Calder A. | year = 2010 | title = Neural abnormalities in early-onset and adolescence-onset conduct disorder | journal = Archives of General Psychiatry | volume = 67 | issue = 7| pages = 729–738 | doi=10.1001/archgenpsychiatry.2010.75 | pmid=20603454 | pmc=4471104}}</ref>

===Risks===
The development of conduct disorder is not immutable or predetermined. A number of interactive risk and protective factors exist that can influence and change outcomes, and in most cases conduct disorder develops due to an interaction and gradual accumulation of risk factors.<ref name="Murray">{{cite journal |author1=Murray J. |author2=Farrington D. P. | year = 2010 | title = Risk factors for conduct disorder and delinquency: Key findings from longitudinal studies | journal = The Canadian Journal of Psychiatry | volume = 55 | issue = 10| pages = 633–642 |doi=10.1177/070674371005501003 |pmid=20964942 |s2cid=21796448 | doi-access =  }}</ref> In addition to the risk factors identified under cause, several other variables place youth at increased risk for developing the disorder, including child physical abuse,<ref name="Murray" /> in-utero alcohol exposure, and maternal [[Smoking and pregnancy|smoking during pregnancy]].<ref>{{cite journal |author1=Larkby C. A. |author2=Goldschmidt L. |author3=Hanusa B. H. |author4=Day N. L. | year = 2011 | title = Prenatal alcohol exposure is associated with conduct disorder in adolescence: Findings from a birth cohort | journal = Journal of the American Academy of Child and Adolescent Psychiatry | volume = 50 | issue = 3| pages = 262–271 | doi=10.1016/j.jaac.2010.12.004|pmid=21334566 |pmc=3042714 }}</ref> Protective factors have also been identified, and most notably include high [[IQ]], being female, positive social orientations, good coping skills, and supportive family and community relationships.<ref>{{cite journal | author = Bassarath L | year = 2001 | title = Conduct disorder: A biopsychosocial review | journal = The Canadian Journal of Psychiatry | volume = 46 | issue = 7| pages = 609–616 | doi = 10.1177/070674370104600704 | pmid = 11582821 | doi-access =  }}</ref>

However, a correlation between a particular risk factor and a later developmental outcome (such as conduct disorder) cannot be taken as definitive evidence for a causal link. Co-variation between two variables can arise, for instance, if they represent age-specific expressions of similar underlying genetic factors.<ref>{{cite journal | author = Rutter M. | author2 = Moffi T. | author3 = Caspi A. | year = 2006 | title = Gene–environment interplay and psychopathology: Multiple varieties but real effects | journal = Journal of Child Psychology and Psychiatry | volume = 47 | issue = 3–4| pages = 226–261 | doi=10.1111/j.1469-7610.2005.01557.x| pmid = 16492258 }}</ref> There have been studies that found that, although smoking during pregnancy does contribute to increased levels of antisocial behaviour, in mother-fetus pairs that were not genetically related (by virtue of in-vitro fertilisation), no link between smoking during pregnancy and later conduct problems was found. Thus, the distinction between causality and correlation is an important consideration.<ref>{{cite journal |last1= Rice |first1= F. |last2= Harold | first2= T.G. | last3= Boivin | first3= J.  | last4=Hay |first4= D.F. |last5= van den Bree |first5= M |last6= Thapar |first6= A. |date= February 17, 2009 |title= Disentangling prenatal and inherited influences in humans with an experimental design
|journal= Proceedings of the National Academy of Sciences of the United States of America |volume= 106 |issue= 7 |pages= 2464–7 |doi= 10.1073/pnas.0808798106 | pmid = 19188591 |pmc= 2634805 |bibcode= 2009PNAS..106.2464R |doi-access= free }}</ref>

===Learning disabilities===
While language impairments are most common,<ref name="McMahon, R. J. 2005"/> approximately 20–25% of youth with conduct disorder have some type of [[learning disability]].<ref>{{cite journal |author1=Frick P. J. |author2=Kamphaus R. W. |author3=Lahey B. B. |author4=Christ M. A. |author5=Hart E. L. |author6=Tannenbaum T. E. | year = 1991 | title = the vast majority of these have ADHD. Academic underachievement and the disruptive behavior disorders | journal = Journal of Consulting and Clinical Psychology | volume = 59 | issue = 2| pages = 289–294 | doi=10.1037/0022-006x.59.2.289|pmid=2030190 }}</ref> Although the relationship between the disorders is complex, it seems as if learning disabilities result from a combination of ADHD, a history of academic difficulty and failure, and long-standing [[socialization]] difficulties with family and peers.<ref>{{cite journal |author=Hinshaw |first=S.P. |year=1992 |title=Externalizing behavior problems and academic underachievement in childhood adolescence: Causal relationships and underlying mechanisms |journal=Psychological Bulletin |volume=111 |issue=1 |pages=127–155 |doi=10.1037/0033-2909.111.1.127 |pmid=1539086}}</ref> However, [[Confounding|confounding variables]], such as language deficits, [[Socioeconomic status|SES]] disadvantage, or [[Development of the nervous system|neurodevelopmental]] delay also need to be considered in this relationship, as they could help explain some of the association between conduct disorder and learning problems.<ref name="Hinshaw" />

===Cognitive factors===
In terms of cognitive function, intelligence and cognitive deficits are common amongst youths with conduct disorder, particularly those with early-onset and have intelligence quotients (IQ) one standard deviation below the mean<ref>Lynham, D. & Henry, B. (2001). The role of neuropsychological deficits in conduct disorders. In J. Hill & B. Maughan (Eds.), ''Conduct disorders in childhood and adolescence'' (pp.235-263). New York: Cambridge University Press.</ref> and severe deficits in verbal reasoning and [[Executive functions|executive function]].<ref>Moffitt, T. & Lynam, D. (1994). The neuropsychology of conduct disorder and delinquency: Implications for understanding antisocial behavior. In D.C. Fowles, P. Sutker, & S.H. Goodman (Eds.), ''Progress in experimental personality and psychopathology research'' (pp. 233-262). New York: Springer.</ref> Executive function difficulties may manifest in terms of one's ability to shift between tasks, plan as well as organize, and also inhibit a prepotent response. These findings hold true even after taking into account other variables such as socioeconomic status (SES), and education. However, IQ and executive function deficits are only one piece of the puzzle, and the magnitude of their influence is increased during transactional processes with environmental factors.<ref>{{cite journal |author1=Pennington B. |author2=Benneto L. | year = 1993 | title = Main effects or transactions in the neuropsychology of conduct disorder? Commentary on "The neuropsychology of conduct disorder | journal = Development and Psychopathology | volume = 5 | issue = 1–2| pages = 153–164 | doi=10.1017/s0954579400004314|s2cid=145599127 }}</ref>

===Brain differences===
Beyond difficulties in executive function, neurological research on youth with conduct disorder also demonstrate differences in brain anatomy and function that reflect the behaviors and mental anomalies associated in conduct disorder. Compared to normal controls, youths with early and adolescent onset of conduct disorder displayed reduced responses in brain regions associated with social behavior (i.e., [[amygdala]], [[ventromedial prefrontal cortex]], [[Insular cortex|insula]], and [[orbitofrontal cortex]]).<ref name="Passa" /> In addition, youths with conduct disorder also demonstrated less responsiveness in the orbitofrontal regions of the brain during a stimulus-reinforcement and reward task.<ref>{{cite journal |author1=Finger E. |author2=Marsh A. |author3=Blair K. |author4=Reid M. |author5=Sims C. |author6=Ng P. |author7=Pine D. |author8=Blair R. | year = 2011 | title = Disrupted reinforcement signaling in the orbitofrontal cortex and caudate in youths with conduct disorder or oppositional defiant disorder and a high level of psychopathic traits | journal = American Journal of Psychiatry | volume = 168 | issue = 2| pages = 152–162 | doi=10.1176/appi.ajp.2010.10010129|pmid=21078707 |pmc=3908480 }}</ref> This provides a neural explanation for why youths with conduct disorder may be more likely to repeat poor decision making patterns. Lastly, youths with conduct disorder display a reduction in grey matter volume in the amygdala, which may account for the fear conditioning deficits.<ref>{{cite journal | author = Raine A | year = 2011 | title = An amygdale structural abnormality common to two subtypes of conduct disorder: A neurodevelopmental conundrum | doi = 10.1176/appi.ajp.2011.11030416 | pmid = 21642478 | journal = American Journal of Psychiatry | volume = 168 | issue = 6| pages = 569–571 }}</ref> This reduction has been linked to difficulty processing social emotional stimuli, regardless of the age of onset.<ref>{{cite journal |author1=Fairchild G. |author2=Passamonti L. |author3=Hurford G. |author4=von dem Hagan C. |author5=Hagen E. |author6=van Goozen S. |author7=Goodyer I. |author8=Calder A. | year = 2011 | title = Brain structure abnormalities in early-onset and adolscent-onset conduct disorder | journal =   American Journal of Psychiatry| volume = 168 | issue = 6| pages = 624–633 | doi=10.1176/appi.ajp.2010.10081184|pmid=21454920 }}</ref> Aside from the differences in neuroanatomy and activation patterns between youth with conduct disorder and controls, neurochemical profiles also vary between groups.<ref name="Capp">{{Cite journal | last1 = Cappadocia | first1 = MC. | last2 = Desrocher | first2 = M. | last3 = Pepler | first3 = D. | last4 = Schroeder | first4 = JH. | title = Contextualizing the neurobiology of conduct disorder in an emotion dysregulation framework. | journal = Clin Psychol Rev | volume = 29 | issue = 6 | pages = 506–18 v|date=Aug 2009 | doi = 10.1016/j.cpr.2009.06.001 | pmid = 19573964 }}</ref> 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.<ref name="Capp" /> 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.<ref>{{cite journal |author1=Gelhorn H. L. |author2=Stallings M. C. |author3=Young S. E. |author4=Corley R. P. |author5=Rhee S. H. |author6=Hewitt J. K. | year = 2005 | title = Genetic and environmental influences on conduct disorder: Symptom, domain, and full-scale analyses | journal = Journal of Child Psychology and Psychiatry | volume = 46 | issue = 6| pages = 580–591 | doi=10.1111/j.1469-7610.2004.00373.x|pmid=15877764 }}</ref> There also tends to be a stronger genetic link for individuals with childhood-onset compared to adolescent onset.<ref>{{cite journal |author1=Burt S. |author2=Truger R. |author3=McGue M. |author4=Iacono W. | year = 2001 | title = Sources of covariation among attention deficit/hyperactivity disorder, oppositional defiant disorder, and conduct disorder: The importance of shared environment | journal = Journal of Abnormal Psychology | volume = 110 | issue = 4| pages = 516–525 | doi=10.1037/0021-843x.110.4.516|pmid=11727941 }}</ref> In addition, youth with conduct disorder also exhibit polymorphism in the monoamine oxidase A gene,<ref>{{cite journal |author1=Foley D. L. |author2=Eaves L. J. |author3=Wormley B. |author4=Silberg J. L. |author5=Maes H. H. |author6=Kuhn J. |author7=Riley B. | year = 2004 | title = Childhood adversity, monoamine oxidase A genotype, and risk for conduct disorder | journal = Archives of General Psychiatry | volume = 61 | issue = 7| pages = 738–744 | doi=10.1001/archpsyc.61.7.738|pmid=15237086 |doi-access= }}</ref> low resting heart rates,<ref>{{cite journal |author1=Baker L. A. |author2=Tuvblad C. |author3=Reynolds C. |author4=Zheng M. |author5=Lozano D. I. |author6=Raine A. | year = 2009 | title = Resting heart rate and the development of antisocial behaviour from age 9 to 14: genetic and environmental influences | journal = Development and Psychopathology | volume = 21 | issue = 3| pages = 939–960 | doi=10.1017/s0954579409000509|pmid=19583891 |pmc=2756992 }}</ref> and increased testosterone.<ref>Coie, J. & Dodge, K. (1998). Aggression and antisocial behavior. In W. Damon (Series Ed.) & N. Eisenberg (Vol. Ed.), ''Handbook of child psychology: Vol.2. Social, emotional, and personality development'' (5th ed., pp.779-862). New York: Wiley.</ref>

===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.<ref name="Hinshaw" /> 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. Moreover, maternal depression has a significant impact on conduct disordered children and can lead to negative reciprocal feedback between the mother and conduct disordered child.<ref>{{Cite journal |last=Gardner |first=Frances E. M. |date=1992 |title=Parent—Child Interaction and Conduct Disorder |url=https://www.jstor.org/stable/23359338 |journal=Educational Psychology Review |volume=4 |issue=2 |pages=135–163 |doi=10.1007/BF01322342 |jstor=23359338 |issn=1040-726X}}</ref> Peer influences have also been related to the development of antisocial behavior in youth, particularly peer rejection in childhood and association with deviant peers.<ref name="Hinshaw" /> 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)<ref name="Hinshaw" /> 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.<ref>{{cite journal |vauthors=Bonin EM, Stevens M, Beecham J, Byford S, Parsonage M | year = 2011 | title = Costs and longer-term savings of parenting programmes for the prevention of persistent conduct disorder: a modelling study | journal = BMC Public Health | volume = 11 | page = 803 | doi=10.1186/1471-2458-11-803 | pmid=21999434 | pmc=3209459 | doi-access = free }}</ref>

===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.<ref name="Hinshaw" /> 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.