Callous and unemotional traits

A CU specifier for conduct disorder was added to DSM-5.[4] The addition "with limited prosocial emotions" to the conduct disorder diagnosis in DSM-5 is to classify a specific subgroup of antisocial youth with distinguishing antisocial behaviors and psychopathic traits.[6] The provision of the CU specifier for CD youth is claimed to improve the diagnostic power, treatment options, and increase the understanding life-course outcomes.[6] A 2008 review concluded that CU did not have the required evidence base to be included as a new diagnosis in DSM-5.[10]

Primatologist Frans de Waal argues that evolutionary theory postulates that biological altruism in primates evolved for the return-benefits it bears the performer.[15] Some evolutionary biologists, therefore, criticize the psychiatric model of callous-unemotional traits (CU) on the grounds that CU is inconsistent with evolutionary continuity. Rather, these biologists argue that if empathy had evolved through mammalian evolution, beginning with empathy restricted to close relatives and extending over the course of evolution to include more distant relatives, then empathy with other humans could be expected to be necessary but not sufficient for human empathy with nonhuman animals. This evolutionary biology model of altruism and empathy thus contrasts with the psychiatric model of CU because the latter implies that cruelty to animals is a predictor of violence to other humans – but not the other way around.[16][17]

Research has attempted to subtype youth with callous-unemotional traits by distinguishing between those with childhood-onset versus adolescent-onset conduct disorder, conduct disorder co-morbid with attention deficit hyperactivity disorder (ADHD), or by the severity and type of aggression displayed.[7] Children with CU traits have more severe conduct disorder, and respond to different management.[4] The Inventory of Callous-Unemotional Traits (ICU) assesses three independent factors in CU traits: uncaring, callous, and unemotional.[18] The severity of CD has been studied in children rated high on CU traits.[8]

CU traits are relatively stable, though some studies suggest that they may decrease over time through effective treatment.[6] Early intervention is thought to be more effective because CU traits are thought to be more malleable early in life.[19]

Childhood-onset CU shows a more aggressive and stable pattern of antisocial behavior with higher rates of CU traits, as well as more severe temperamental and neuropsychological risk factors relative to their adolescent-onset counterparts.[22] Children with combined CD and ADHD are more likely to show features associated with psychopathy, but only in those who have high rates of CU traits.[23] In support of the idea of lifetime persistence of CU traits, childhood-onset delinquency has been more strongly associated with psychopathic traits than adolescent-onset delinquency.[24] A longitudinal twin study of children with CD showed that high or increasing levels of CU traits comorbid with CD presented with the most negative outcomes after twelve years in relationships with peers and family, as well as emotional and behavioral problems, as compared to those with low CU traits or CD alone.[25] In addition, adolescents with CU traits have shown higher likelihood to commit a violent crime within a two-year period of their release from a correctional facility than those without CU traits.[26] Antisocial youth with CU traits tend to show less response to treatment.[8]

A systematic review found that CU traits were associated with poorer outcomes in family-based interventions for conduct problems. This suggests pre-treatment data on CU traits is clinically informative in terms of the prognostic status of children and young people with CU traits.[27]

Due to the potential severity of antisocial and violent traits seen in adult psychopathy, research has focused on identifying the associated traits in childhood. In adult psychopathy, individuals with primarily affective and interpersonal deficits show a distinct etiology.[28] Similarly, different subtypes of aggressive and antisocial behaviors in youth may predict distinct problem-behaviors and risk factors. There have been a number of attempts to officially designate psychopathic-like traits in antisocial youths based on the affective and interpersonal traits of psychopathy. The third edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM III) divided conduct disorder into four subtypes: undersocialized-aggressive, undersocialized-nonaggressive, socialized-aggressive, and socialized-nonaggressive in an attempt to recognize the existence of psychopathic traits in children.[23] The distinction between "socialized" and "undersocialized" children was the most pertinent in distinguishing between psychopathic-like youths. According to these definitions, "undersocialized" children exhibited characteristic behaviors of psychopathy, including: lack of empathy, lack of affection, and inappropriate social relationships (DSM III). This differed from "socialized" individuals, who were able to form healthy social attachments to others, and whose aggressive and antisocial acts typically derived from engagement in a deviant social group (e.g. youth gangs).

Following the publication of DSM-III, these distinctions prompted research, but there were still issues with the terminology in diagnosing the core features of the undersocialized versus socialized subtype. The word undersocialized was used in order to avoid the negative connotations of psychopathy, but was commonly misinterpreted to mean that the child was not well socialized by parents or lacked a peer group. Also, the operational definition failed to include dimensions that could reliably predict the affective and interpersonal deficits in psychopathic-like youths. Due to these issues, the American Psychiatric Association removed the undersocialized and socialized distinctions from the conduct disorder description in the DSM after the third edition. The only subtypes that have been included in the manual since then relate to the time of onset: childhood-onset (before age 10), adolescent-onset (absence of antisocial traits before age 10), and unspecified-onset.[22]

• Antisocial personality disorder
• Apathy
• Conduct disorder
• Psychopathy