Callous-unemotional traits and the treatment of conduct problems in childhood and adolescence: a comprehensive review.

Clin Child Fam Psychol Rev DOI 10.1007/s10567-014-0167-1

Callous-Unemotional Traits and the Treatment of Conduct Problems in Childhood and Adolescence: A Comprehensive Review David J. Hawes • Matthew J. Price Mark R. Dadds

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Ó Springer Science+Business Media New York 2014

Abstract The treatment of conduct problems among children and adolescents with callous-unemotional (CU) traits has been subject to much speculation; however, treatment outcome research has been surprisingly limited and findings have been mixed. This review examines the research to date in this field as it pertains to two key questions. First, are CU traits associated with clinical outcomes and processes in the family based treatment of child and adolescent conduct problems? Second, can family based intervention produce change in CU traits? Using a systematic search strategy, we identified 16 treatment outcomes studies that can be brought to bear on these questions. These studies provide strong evidence of unique associations between CU traits and risk for poor treatment outcomes, while at the same time indicating that sociallearning-based parent training is capable of producing lasting improvement in CU traits, particularly when delivered early in childhood. We discuss the potential for this emerging evidence base to inform the planning and delivery of treatments for clinic-referred children with CU traits, and detail an ongoing program of translational research into the development of novel interventions for this high-risk subgroup. Keywords Callous-unemotional traits Psychopathy Treatment Conduct problems Conduct disorder Oppositional defiant disorder D. J. Hawes (&) M. J. Price School of Psychology, University of Sydney, Sydney, NSW 2006, Australia e-mail: [email protected] M. R. Dadds The University of New South Wales, Kensington, NSW, Australia

Persistent conduct problems in childhood are associated with great social and economic burden and are the most common precursor to the major psychiatric disorders of adulthood (Erskine et al. 2013; Kim-Cohen et al. 2003; Romeo et al. 2006). Populations of children with conduct problems are also known to conceal significant heterogeneity. For all that they have in common these children may follow risk pathways that diverge markedly from one another. Research into these pathways has grown rapidly in recent years, with emerging evidence informing developmental models of antisocial behavior as well as revisions to the criteria for the disruptive behavior disorders in the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM–5; American Psychiatric Association 2013). The most significant such revision is the introduction of a specifier for children who meet criteria for conduct disorder (CD), while also demonstrating ‘limited prosocial emotions’, as operationalized by callousunemotional (CU) traits. Theoretically, the core features by which CU traits have been defined (e.g., a lack of guilt, a lack of empathy, and shallow affect) correspond to the affective component of psychopathy. The application of the psychopathy construct in childhood has drawn understandable scrutiny; however, the importance of identifying such features early in life has received growing recognition among clinicians and neuroscientists (Rutter 2012; Viding et al. 2012). There is now extensive support for the subtyping of child and adolescent conduct problems based on the presence of high versus low levels of CU traits (see Frick et al. 2013). Among children and adolescents with conduct problems, those with high levels of CU traits exhibit a particularly severe and chronic trajectory of antisocial behavior. They are also characterized by high levels of proactive or instrumental aggression and a range of unique social-cognitive and neurobiological

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correlates related to the processing of emotional stimuli and reinforcement learning. Evidence of these correlates has been reported not only in samples of children and adolescents with CD, but also those with oppositional defiant disorder (ODD), and in studies that have examined distributions of CU traits in community samples. Since first introduced in the literature, the concept of CU traits has been subject to continual speculation regarding implications for clinical practice with children and families. However, direct tests of such implications in treatment outcome research have been surprisingly limited, and findings to date have been mixed. The aim of this paper is to provide a systematic review of the emerging evidence base in this field as it pertains to two broad questions. First, are CU traits associated with clinical outcomes and processes in the treatment of child and adolescent conduct problems? Second, can clinical intervention produce change in CU traits? We examine the potential for this evidence to inform the planning and delivery of treatments for clinic-referred children with CU traits and discuss an ongoing program of translational research into the development of novel interventions for this putative subgroup. For the purpose of this review, we focus on interventions that are family based—that is, interventions in which parents/caregivers are active participants—as opposed to those in which treatment is delivered directly to a referred/ detained child without direct involvement by family members. The rationale for this is twofold. As outlined below, the most effective interventions presently available for conduct problems in children and adolescents are family based. Additionally, there is good reason to believe that CU traits may interact with the mechanisms through which these interventions operate.

positive family interactions extinguished (Hawes and Dadds 2005a; Patterson 1982). Settings outside of the home are thought to play an increasingly proximal role in the amplification and transformation of conduct problems across childhood, as peer interactions confer risk through rejection, coercion, and the selective reinforcement of deviant talk (Dishion and Tipsord 2011). Parenting practices continue to make important contributions to trajectories of antisocial behavior across adolescence ;however, the precise parent–child dynamics of proximal importance in this period shift from those related to limit setting in the home to those related to the regulation of children’s peer activities in external settings (Dishion and Patterson 2006). In addition to parenting practices associated with behavioral control and monitoring, there is considerable evidence that the affective quality of the parent–child relationship is likewise implicated in risk pathways to conduct problems (Stormshak et al. 2000). Rather than occurring as orthogonal dimensions, data support the view that parental control and warmth are highly interrelated and dynamically connected (Dishion and McMahon 1998). For example, social-learning-based interventions that aim to improve positive parental control through reinforcement strategies such as praise have been found to enhance warm/ sensitive responding, despite not explicitly targeting such responding (O’Connor et al. 2013). Furthermore, various indices of the parent–child relationship have been found to make contributions to conduct problems across earlychildhood and adolescence independent of parental control and monitoring (e.g., Fosco et al. 2012), and through interactions with such parenting practices (e.g., Kochanska et al. 2009).

Conduct Problems and the Family Environment

CU Traits, Child Development, and Family Environment

Current models of antisocial behavior reflect a developmental-ecological perspective on mental health, wherein the emergence of self-regulatory capacities is understood to be highly embedded in the multiple settings or ecologies (e.g., family, school, peers) that are nested within a child’s broader environment. Importantly, environmental contributions to conduct problems are understood to operate largely through mechanisms located in the moment-tomoment interactions between parents and children. Evidence supports conceptualizations of these mechanisms based on social learning (operant) theory, which emphasize the parental modeling of aggression, and escalating cycles of parent–child coercion—or ‘reinforcement traps’— maintained by escape-avoidance conditioning. In these cycles, family members’ use of aversive control tactics (e.g., whining, nagging, shouting, hitting) is rewarded and

In contrast to dominant models of child and adolescent conduct problems, developmental accounts of psychopathy and CU traits have placed a primary emphasis on factors that are biologically based (see Blair et al. 2006). Childhood CU traits have been associated with functional abnormalities in brain regions involved in the processing of basic emotional salience, reinforcement learning, and emotion regulation (e.g., amygdala, ventromedial, prefrontal, orbitofrontal cortex, and caudate; e.g., Jones et al. 2009). In addition, structural MRI data from children with CU traits has indicated increased gray matter concentration in several brain areas implicated in decision making, moral processing, and self-reflection (e.g., De Brito et al. 2009). Twin studies have found that CU traits in childhood show moderate-to-high levels of heritability (Viding and McCrory 2012), and emerging research into the molecular genetics

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of CU traits has implicated the serotinergic (Moul et al. 2013) and oxytocin systems (Beitchman et al. 2012; Dadds et al. 2014a, 2014b). In addition to evidence that there is a significant genetic component to CU traits, it has also been found that the conduct problems of children with high levels of CU traits have higher genetic loadings than those of low-CU children (e.g., Viding et al. 2005). It is now widely recognized that environmental contexts serve to potentiate the expression of biological vulnerabilities associated with risk for psychopathology. As such, key risk factors for antisocial behavior that fall within the domains of temperament, social-cognitive style, and intelligence have been conceptualized as entrained biosocial traits (Dishion and Patterson 2006). Entrainment refers to the role of environments in structuring neural pathways implicated in automatic, overlearned behavior patterns (Lewis 2000). Characteristics such as response perseveration, behavioral inhibition, hyperactivity, and irritability are assumed to be shaped through thousands of interactions and routines within the family and broader social contexts across development, and there is growing evidence that CU traits may conform likewise to such a conceptualization. This evidence has provided an emerging picture of the parenting processes that contribute to the behavioral adjustment of children with CU traits, as well as the expression of such traits over time. Consistent with evidence of amygdala-dysfunction among children with high levels of CU traits (e.g., Deeley et al. 2006; Jones et al. 2009), it has been proposed that the poor recognition of fear and distress cues that characterizes these children may be attributable to impairments in the allocation of attention to emotionally salient stimuli—in particular, the eyes of faces (Dadds 2006). Importantly, such impairments are evident among these children during family interactions beginning early in life. Observational studies of families have found that high-CU boys demonstrate consistent impairments in eye contact toward their parents and suggest that this lack of eye contact is primarily child driven. This lack of eye contact does not appear to be a function of reduced eye contact from mothers; however, it does appear that fathers of high-CU boys may show a similar deficit (Dadds et al. 2012; Dadds, Allen, McGregor, Woolgar, Viding, and Scott, in press; Dadds et al. 2011). Dadds et al. (2011) proposed that among children with CU traits, a lack of eye contact with attachment figures early in life may prevent them from participating in the critical parent–child exchanges that establish the foundations for emotion understanding, conscience, and empathy, and set in train a developmental cascade involving ongoing failures of adaptation across these domains. Longitudinal research has found that exposure to harsh and inconsistent parenting predicts increased levels of CU traits over time (e.g., Willoughby et al. 2013), while

decreased levels of CU traits have been predicted by high levels of positive parenting and warmth (e.g., Pardini et al. 2007). Child-driven effects also appear to contribute to such processes, with high levels of CU traits found to predict increased levels of harsh and inconsistent discipline and reduced parental warmth (e.g., Hawes et al. 2011; Salihovic et al. 2012). Such evidence is consistent with thesis that CU traits are implicated in an evocative gene– environment correlation, whereby the behavior of children with a genetic vulnerability to CU traits elicits adverse parenting behaviors that in turn amplify both CU and conduct problems over time (Larsson et al. 2008). However, findings to the contrary have also been reported. For example, a longitudinal monozygotic twin differences study conducted by Viding et al. (2009) found that quality of parenting did not function as a non-shared environmental risk factor for prospective levels of CU traits. In addition to emerging evidence of a transactional relationship between CU traits and family environment, there is also considerable evidence that CU traits interact with family environment, moderating the association between parenting practices and risk for child conduct problems. Compared to the conduct problems of children who are free from CU traits, those of high-CU children appear to be less proximally associated with negative parenting practices such as harsh/inconsistent discipline. For high-CU children, it is a lack of parental warmth/ involvement rather than exposure to negative parenting that appears to be most proximal to the development and maintenance of their conduct problems (see Waller et al. 2013). Interestingly, there is evidence to suggest that lack of parental warmth may be more robustly associated with the conduct problems of children with CU traits than those without (e.g., Kochanska et al. 2013; Pasalich et al. 2011) and are consistent with analogous research into interactions between child temperament (e.g., fearlessness) and conscience development in toddlers (e.g., Fowles and Kochanska 2000).

Conduct Problems, CU Traits, and Clinical Intervention Family process models of conduct problems have been translated into a range of widely disseminated and evaluated interventions for children and adolescents in recent decades. The most effective treatment currently available for conduct problems in early- to middle-childhood is parent training based on social learning theory (Comer et al. 2013; Eyberg et al. 2008; Michelson et al. 2013). Interventions of this kind typically commence with skills training to increase positive reinforcement of desirable child behavior, followed by discipline-focused components

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in which parents are trained to use consistent, non-forceful consequences (e.g., time out) to set limits on negative behavior. Research into mechanisms of change in such interventions has found child outcomes to be accounted for both by reductions in harsh/inconsistent parenting and increases in positive parenting practices (e.g., Beauchaine et al. 2005; Hawes and Dadds 2006; Kling et al. 2010). The interventions with the strongest support in late childhood and adolescence are those that combine parent training components with child-focused skills training targeting social-cognitive deficits related to emotion regulation (e.g., anger management) and social problem solving. Research indicates that the effects of such interventions are nonetheless mediated by changes in parenting practices (e.g., Dekovic et al. 2012), thereby emphasizing the importance of family based mechanisms to the treatment of conduct problems across both childhood and adolescence. Although the majority of children with clinic-referred conduct problems appear to respond to family based intervention, the effect sizes associated with these interventions are often not large. For example, meta-analytic research has indicated that parent training interventions are associated with a mean effect size of only 0.47 (range from 1.68 to -0.06) (McCart et al. 2006). Further, evidence regarding the factors that predict, influence, or account for variations in treatment outcomes remains limited and has been largely inconsistent to date (Eyberg et al. 2008). Poor response to intervention has been associated with a range of social adversity factors that may interfere with families’ implementation of treatment strategies and engagement with clinical services. These include socioeconomic disadvantage, minority group status, younger maternal age, and parental psychopathology (e.g., Beauchaine et al. 2005; Gardner et al. 2010; Lundahl et al. 2006; Reyno and McGrath 2006). In contrast, the notion that child characteristics may contribute to individual differences in treatment response has received relatively little attention, as have the mechanisms through which such characteristics might interact with core therapeutic processes (Matthys et al. 2012; Schechter et al. 2012). As outlined already, there is now considerable evidence that the risk processes that account for conduct problems among children with high levels of CU traits differ somewhat to those implicated in the conduct problems of children without these traits. As this evidence has grown, researchers have become increasingly interested in the extent to which the mechanisms targeted in existing treatments for child conduct problems map onto those that account for the problems of children with CU traits. Specifically, findings would suggest that key components of current interventions focused on reducing negative parenting would be less likely to translate into behavior change among high-CU than low-CU children. At the same

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time, such evidence indicates that family environment may play a significant role in shaping CU traits and that the family environment domains of importance to such outcomes correspond to some degree with those targeted in social-learning-based parent training (i.e., harsh/inconsistent discipline, positive reinforcement). As noted, these same interventions have also been found to significantly enhance parental warmth/sensitivity—a domain of particular importance to the behavioral and emotional adjustment of children with CU traits (O’Connor et al. 2013). As such, there are grounds to predict that parent training interventions have the potential to contribute to change in CU traits given the appropriate conditions.

Systematic Review Method A systematic review was conducted using three databases: MEDLINE, PsycINFO, and Scopus. The search strategy combined terms to identify studies investigating CU traits and clinical intervention: (callous* OR psychopathy OR psychopathic OR psychopath OR sociopath* OR unemotional) AND (Treatment OR therapy OR intervention). No date or publication restrictions were imposed on the initial search, which returned 5,258 studies in total. Titles and abstracts of identified articles were screened based on criteria pertaining to the specific aims of the review as follows: (a) samples with an upper age range of 18 years from community, clinic, juvenile justice, or research settings; (b) samples characterized by either clinically significant conduct problems or identified as ‘at risk’ for conduct problems; (c) measurement of CU traits via parent, teacher, or youth self-report using measures that are either established or supported by psychometric investigation; (d) treatment outcome designs involving family based intervention, as defined in terms of treatments that were delivered at least in part to parents/caregivers; and (e) data reported on associations between CU traits and clinical change in conduct problems, OR clinical change in CU traits. No additional criteria were specified regarding study design; however, only English language and peer-reviewed publications were retained. This screening resulted in the exclusion of 17 studies that were limited to interventions based exclusively on child/adolescent-focused components (e.g., Caldwell et al. 2007; Haas et al. 2011; Rogers et al. 2004; Salekin et al. 2012; Waschbusch et al. 2007). Based on this method, a total of 16 studies were retained. These include 11 studies reporting on CU traits in relation to clinical change in conduct problems following family based intervention, and six studies reporting on the effects of family based intervention on change in CU traits. Studies were systematically appraised for methodological limitations according to

Clin Child Fam Psychol Rev Table 1 Characteristics of included studies Study

Sample Size

Sample type

% Female

Age range

Conduct problems measure

CU traits measure

Type of intervention

Format and delivery

Butler et al. (2011)

108

Court ordered

17.8

13–17

Questionnaire (P,Y)

APSD (P,Y,T)

Parent and child therapy

Community-based, individual parent and child sessions across 20.4 (average) weeks

Dadds et al. (2012)

195

Clinicreferred

22

6–16

APSDSDQ (P,Y,T)


Outpatient service; eight individual parent and child sessions

Hawes and Dadds (2005a)

49

APSDSDQ (P)

Parent training

University-based, 10 weekly parent sessions

Hawes and Dadds (2007)

49

APSDSDQ (P)

Parent training


Hawes et al. (2013)

Questionnaire (P,T) DSM-IV diagnosis

APSDSDQ (P,T)

Parent training


Questionnaire (P)

APSD (P)

Parent training

Seven online sessions and clinician contact, delivered across 10 weeks

Offence records Questionnaire (P,Y,T) DSM-IV diagnosis Clinicreferred

0

4–8

Questionnaire (P)

Clinicreferred

0

95

Clinicreferred

29.4

3–9

Ho¨gstro¨m et al. (2013)

57

Clinicreferred

46

3–11

Hyde et al. (2013)

731

High-risk

49

2–4

Questionnaire (P) Observation

ASEBAECBI (P)

Parent training

Parent training sessions offered to selected families during preventive intervention

Kimonis et al. (2014)

63

Clinicreferred

27

3.8 (mean)

Questionnaire (P)

ASEBA (P)

Parent training

Outpatient service; 12.1 (average) weekly individual sessions

Kolko et al. (2009)

139

Clinicreferred

15

6–11

Questionnaire (P,T,Y)

APSD (T)

Parent and child

University- and community-based settings; 21 weekly individual sessions with parent and child

Kolko & Pardini (2010)

177

Clinicreferred

19.2

6–11

Questionnaire (P,T,Y)

APSD (T)


University and community-based settings; 21 weekly individual sessions with parent and child

Manders et al. (2013)

256

Clinicreferred & court ordered

26.6

12–18

Questionnaire (P,Y)

ICU (P)


Home/community-based, individual parent and child sessions across 5.72 (average) months

Masi et al. (2011)

38

Clinicreferred

26.3

6–14

Questionnaire (P) Clinician rating

APSD (P,Y);

DSM-IV diagnosis

ICU (P,Y)


Outpatient service, individual parent sessions and child groups across [ 6 months

6–14

Questionnaire (P)

APSD (P)


Outpatient service, individual parent sessions and child groups across [ 6 months

4–9

DSM-IV diagnosis Questionnaire (P)

PSD (P)

Parent training

Home-based, 20 (average) individual parent sessions across 8-month period

APSDICU (P)

Parent training

Community-based; 10-14 parent group sessions (with 5-7 couples)

DSM-IV diagnosis 4–8

Questionnaire (P) DSM-IV diagnosis

DSM-IV diagnosis

DSM-IV diagnosis

Masi et al. (2013)

118

McDonald et al. (2011)

66

Somech & Elizur (2012)

209

Clinicreferred

13.5

High-risk

nr

DSM-IV diagnosis High-risk

20

2–5

Questionnaire (P)

123

Clin Child Fam Psychol Rev Table 1 continued Study

Sample Size

Sample type

% Female

Age range

Conduct problems measure

CU traits measure

Type of intervention

Format and delivery

White et al. (2013)

134

Court ordered

28.4

11–17

Questionnaire (P,Y)

ICU (P,Y)


Community-based, 9.6 (average) weekly individual sessions with parent and youth

Offence records

P parent, Y youth, T teacher, DSM-IV diagnostic and statistical manual of mental disorders, Fourth Edition, APSD antisocial process screening device, SDQ strengths and difficulties questionnaire, ASEBA Achenbach system of empirically based assessment, ECBI Eyberg child behavior inventory, ICU inventory of callous unemotional traits, PSD psychopathy screening device

(a) sample size; (b) measurement of CU traits; (c) design (e.g., control groups, duration of follow-up); (d) baseline severity of conduct problems; and (e) investigation of process variables (e.g., dropout, parental implementation of treatment strategies, and child responses to specific components of treatment).

Study Characteristics and Limitations Key methodological details for the treatment outcome studies identified are reported in Table 1. Although 15 reported studies met the inclusion criteria, the distinct samples involved in these studies numbered only 12, with data on distinct questions at times reported in different papers (Hawes and Dadds 2007; Kolko and Pardini 2010). These samples comprised a total of 2,345 children and adolescents with 2–18 years of age. Given that individual sample sizes comprised fewer than N = 75 participants in six of these studies, it is apparent that a reliance on small samples has been a frequent limitation of this research. Consistent with broader treatment outcome research in the field of child conduct problems, these samples were also male dominated. All studies used either established measures of CU, such as the Antisocial Process Screening Device (APSD; Frick and Hare 2001) and the Inventory of Callous Unemotional Traits (ICU; Frick 2004), or measures supported by psychometric investigation, including modifications or combinations of items from these measures with items from measures such as the Strengths and Difficulties Questionnaire (SDQ; Goodman, 1997), Achenbach System of Empirically Based Assessment (ASEBA; Achenbach and Rescorla 2000), and Eyberg Child Behavior Inventory (ECBI; Eyberg and Pincus 1999). However, most studies (60 %) relied on singleinformant reports on these measures. CU traits have often been viewed as a potential moderator of treatment effects. Conventional definitions of moderation in the clinical literature refer to baseline or pre-randomization characteristic (i.e., exists prior to treatment and not a function of treatment) that can be

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shown to interact with treatment condition on outcome measures. Moderator variables influence the strength or direction of the relationship between treatment and outcome and may inform for whom, or under what conditions, a treatment is effective (Kraemer et al. 2002). Current conceptualizations also distinguish between moderators and predictors. Predictors, or prognostic indicators, are pre-treatment attributes that bestow the same relative prognosis to subgroup members regardless of what treatment they are exposed to. They are associated outcomes regardless of treatment condition. In contrast, a moderator variable must interact with treatment condition (Kazdin and Weisz 2003; MacKinnon et al. 2013). Based on these definitions, the potential to determine the status of CU traits as a predictor versus moderator is dependent in part upon study design. Among the 11 studies examining CU traits in relation to clinical change in conduct problems, only three involved randomization to distinct treatment conditions (Dadds et al. 2012; Hyde et al. 2013; Manders et al. 2013) and can therefore technically provide data on moderation effects. In terms of sample characteristics, participants were by and large clinic-referred on the basis of clinically significant conduct problems, whereas three studies included participants who were court-ordered for treatment. The study reported by Hyde et al. (2013) is a noteworthy exception, in that it was concerned with an intervention strategy for the prevention of conduct problems across childhood, as opposed to a treatment for existing conduct problems. A large proportion of the sample (51 %) did not show clinically meaningful features of conduct problems at baseline and did not receive the parent training component of the intervention. Furthermore, due to the low reliability of the CU traits measure at time 1 (when the sample were aged 2), it was not possible to examine baseline CU traits as a predictor of intervention outcomes. Rather, tests of CU traits as a predictor/moderator were conducted using time 2 measures of CU traits collected 12 months after the commencement of the intervention. The examination of clinical processes related to CU traits in family based intervention has been particularly

Clin Child Fam Psychol Rev Table 2 Findings pertaining to CU traits and clinical change in conduct problems Study

Treatment outcomes

Treatment processes

Main methodological limitations

Dadds et al. (2012)

Treatment response moderated by CU traits: high-CU traits associated with increased CP at 6-months follow-up; novel ERT intervention enhanced treatment gains, but only among high-CU participants

ERT produced change in CP independent of change in the emotion recognition skills targeted. Treatment dropouts exhibited higher CU traits than completers

Broad age range

Hawes and Dadds (2005b)

CU traits predicted increased ODD symptoms at 6-months follow-up

Parents’ implementation of PT skills not associated with CU traits. Association between CU traits and treatment outcomes independent of this implementation

Small sample size; single-informant CU traits; no control group

Hawes et al. (2013)

CU traits predicted increased ODD symptoms at 6-months follow-up, across multiple reporters (mothers, teachers) of CU traits

CU traits not associated with number of sessions attended

No control group

Ho¨gstro¨m et al. (2013)

CU traits predicted change in CP: significant drop in ECBI intensity scores for low-CU but not high-CU group

CU traits associated with neither baseline levels of parenting practices nor change in parenting practices across treatment

Small sample size; broad age range; single-informant CU traits; no followup beyond post; no control group

Hyde et al. (2013)

Deceitful-callous behaviors predicted increased levels of CP over time, however, did not moderate intervention (prevention) effects

Not reported

Low base rate of significant CP; majority of sample did not participate in treatment; pre-intervention data on CU traits not analyzed

Kimonis et al. (2014)

CU traits predicted post-treatment CP among children with development delay

CU traits not associated with CP following positive parenting component—only following discipline component. Treatment dropouts exhibited higher CU traits than completers

Small sample size; single-informant CU traits; no follow-up beyond post; no control group

Kolko & Pardini (2010)

CU traits did not predict poor treatment outcomes; CU traits did predict increased reductions in ODD symptoms

Not reported

Single-informant (teacher) CU traits; form of treatment unknown in TAU (21 % of sample); no control group


CU traits moderated treatment effects: MST significantly more effective among low-CU than high-CU youths

Not reported

Single-informant (parent) CU traits; no follow-up beyond post

Masi et al. (2011)

CU traits significantly predicted nonresponder status (yet non-significant with Bonferroni correction)

Not reported

Small sample size; broad age range; analyses did not control for pretreatment CP; no control group

Masi et al. (2013)

CU traits significantly predicted nonresponder status

Not reported

Broad age range; no control group

White et al. (2013)

In analyses controlling for pre-treatment CP, CU traits associated with youth perceptions of poorer improvement, and increased violent offending across treatment

Not reported

No control group; no outcomes other than arrest statistics at follow-up

CP conduct problems, CU callous-unemotional traits, MST multi-systemic therapy, TAU treatment as usual

limited. Eight of the 15 identified studies reported on CU traits in relation to variables related to therapeutic engagement and adherence (e.g., treatment attendance and dropout); however, only five of these explicitly measured parenting variables, two of which involved the same sample (Hawes and Dadds 2005b, 2007). Mechanisms of change were investigated with statistical tests of mediation in three studies only (Dadds et al. 2012; McDonald et al. 2011; Somech and Elizur 2012).

Results CU Traits and Clinical Change in Conduct Problems The key findings and limitations of the 11 studies that report on CU traits and clinical change in conduct problems following family based intervention are summarized in Table 2. In examining associations between CU traits and the effects of family based intervention, we make a

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distinction between studies that have investigated interventions based exclusively on parenting targets (i.e., parent training) versus those that include the child as an active participant in therapy. Such a distinction has often been emphasized in interpretations of findings concerning CU traits as a predictor of treatment response. This includes speculation that the inclusion of child-focused targets may serve to overcome limitations associated with treatment components that rely primarily on mechanisms based in the parent–child relationship (e.g., Manders et al. 2013; Waller et al. 2013; White et al. 2013). Parent Training Interventions: Outcomes CU traits have been examined as a predictor of conduct problems following parent training intervention in five studies to date. Four out of these five studies report a significant association between CU traits and poor treatment outcomes. This finding was first reported by Hawes and Dadds (2005b), who examined the treatment outcomes of boys with ODD (aged 4–8) years whose parents participated in a 10-week parent training program (Integrated Family Intervention for Child Conduct Problems; Hawes and Dadds 2006) delivered individually to families. Mother-reported CU traits were found to uniquely predict diagnostic status at 6-month follow-up, independent of pretreatment symptom severity and comorbid symptoms of ADHD. Using the same parent training program, Hawes et al. (2013) subsequently replicated this finding in a mixedgender sample of children (3–9 years) with primary presentations of ODD and high levels of comorbid symptoms (anxiety disorders, ADHD, and autism spectrum disorder). Pre-treatment data on child CU traits were collected form mothers, fathers, and teachers, and modeled as a latent variable. This multi-informant index of CU traits was found to uniquely predict higher levels of ODD symptoms at 6-month follow-up, independent of baseline severity. CU traits remained a significant predictor when indexed only by mother reports and teacher reports, respectively. The absence of an effect for father-reported CU traits was thought to be associated with reduced power due to the smaller number of fathers in the sample. The only other study to have examined CU traits as a predictor of response to a face-to-face parent training intervention is that reported by Kimonis et al. (2014). The authors tested parent-reported CU traits as a predictor of response to Parent Child Interaction Therapy, in two samples of preschoolers at risk for conduct problems (mean age 46 months). This ‘at-risk’ status was based on elevated Eyberg Child Behavior Inventory scores, and the presence of either a developmental delay (sample A) or premature birth (sample B). CU traits were found to significantly

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predict post-treatment conduct problems in sample A, but not B, controlling for pre-treatment symptom severity. Levels of CU traits also differed between these groups, with mean levels found to be higher in the sample for which CU traits were associated with poor outcomes. Ho¨gstro¨m et al. (2013) examined CU traits as a predictor of response to an internet-based parent training program shown to significantly reduce conduct problems in a previous randomized controlled trial (RCT) (Enebrink et al. 2012). This intervention comprised seven online sessions focused on parenting strategies, with additional support provided through intermittent contact with a therapist and participation in an online forum with other parents. Participants were children aged 3–11 years, characterized on the whole by moderately severe conduct problems (61.4 % diagnosed with ODD/CD). Group-based analyses indicated an interaction between pre-treatment CU traits (high/low) and time (pre/post). Specifically, children low in CU traits showed a significant drop in conduct problems in the order of a large effect, while high-CU children demonstrated no change in conduct problem severity. Post hoc analysis indicated that this effect was independent of pre-treatment severity of conduct problems. Hyde et al. (2013) re-analyzed data from a large community sample of children (aged 2 years at baseline) characterized by social adversity and elevated scores on a measure of conduct problems. This sample was originally used to evaluate the effects of the family check-up—a preventive intervention in which families are provided with three annual assessment visits involving motivational interviewing and the option to access parent training sessions (see Dishion et al. 2008). Hyde et al. (2013) constructed a novel index of CU traits—referred to as ‘deceitful-callous’—from items within the CBCL. Families were randomized to either the family check-up or health/ nutrition services. Growth curve analyses indicated that although CU traits predicted increased levels of conduct problems over time, they did not moderate response to the family check-up. As summarized in Table 2, these findings must be considered in light of numerous design factors, including the investigation of a prevention strategy rather than treatment for existing conduct problems, and the omission of baseline data on CU traits from analyses. Parent Training Interventions: Processes Findings regarding the association between CU traits and attendance/dropout in parent training interventions have been somewhat mixed. In the studies reported by Hawes and colleagues, CU traits have not been significantly associated with number of sessions attended by parents or the status of participants when assigned to completer versus non-completer categories (Hawes and Dadds 2005b,


2007; Hawes et al. 2013). In contrast, Kimonis et al. (2014) found that children in families who dropped out of treatment exhibited significantly higher levels of CU traits than treatment completers. Hawes and Dadds (2005b) collected multi-method data on parents’ implementation of the specific skills taught in parent training (positive reinforcement of desirable behavior, use of clear concrete commands, and contingent, non-reactive limit setting). Parents’ implementation of these skills was indexed periodically throughout treatment, through both self-reports and the observational coding of parent–child interactions in the home. CU traits were not associated with the quality of this implementation. Additionally, CU traits were found to predict diagnostic treatment outcomes when controlling for individual differences in this implementation (Hawes and Dadds 2005b). Similar findings were reported by Ho¨gstro¨m et al. (2013), who collected self-report data on positive and negative parenting practices pre- and post-treatment. Baseline parenting practices were not found to differ between families of children with high versus low levels of CU traits. Repeated measures analyses of parenting at preand post-treatment showed that increases in praise and positive incentives were in the order of a medium effect size (Cohen’s d = .48) for parents of children with low levels of CU traits, yet extremely small in size among parents of high-CU children (Cohen’s d = .04). Despite this, change in parenting practices was not found to be statistically moderated by CU traits, and thereby could not be seen to account for the reduced effectiveness of parent training among children with high levels of CU traits in this sample. These studies also provide some preliminary evidence regarding the extent to which children’s responses to distinct components of parent training may vary as a function of CU traits. Parent-reported data collected by Hawes and Dadds (2005b) indicated that CU traits were negatively associated with boys’ expressions of negative affect when being disciplined with time out. The effectiveness of time out with respect to behavior change was also inversely associated with CU traits. Conversely, boys with higher levels of CU traits were found to be just as responsive to positive reinforcement strategies as those with lower levels of CU traits. Kimonis et al. (2014) reported somewhat analogous findings when examining mid-treatment measures of conduct problems collected immediately following the completion of an initial positive parenting component of treatment versus those collected following the completion of a second discipline-focused component. CU traits were not associated with conduct problems following the positive parenting component, but were upon completion of the discipline component. The findings from both of these studies were tentatively interpreted as support for the

notion that children with CU traits may be less responsive to discipline (punishment)-based strategies, than positive (reward)-based strategies, in line with broader evidence of punishment insensitivity among children with CU traits (Dadds and Salmon 2003). Parent and Child Therapy: Outcomes To date, six studies have tested CU traits as a predictor/ moderator of conduct problems following family based interventions involving parent and child-focused components. The findings of these studies are somewhat more mixed than those of the aforementioned parent training studies. Significant associations between CU traits and poor treatment outcome are reported in four of these studies. In the largest is these, Manders et al. (2013) randomised a mixed-gender clinic-referred/court-ordered sample (aged 12–18 years; n = 256) to multi-systemic therapy (MST) versus treatment as usual (TAU). The latter consisted of individual counseling and family therapy provided by a variety of juvenile justice, welfare/health services. CU traits were found to moderate treatment effects, such that MST was significantly more effective in reducing conduct problems among youths with low levels of CU traits than among those with high levels of CU traits. Specifically, MST produced a significant decrease in post-treatment conduct problems among cases characterized by low levels of CU traits, while conferring no advantage over TAU for high-CU youths. This moderation effect was evident when treatment outcomes were operationalized using either parent or youth reports of conduct problems severity. It was also independent of an effect for impulsive conduct problems, which were associated with poor outcomes regardless of condition, and thereby functioned as a predictor rather than moderator of treatment response. Likewise, Dadds et al. (2012) found CU traits to be a moderator of treatment response in a sample of children and adolescents (aged 6–16 years) recruited from an outpatient community health setting that specializes in services for disadvantaged families. This study was the first— and to date, only—trial to test whether the treatment outcomes of children with CU traits can be enhanced by combining parent training with a novel intervention to target key social-cognitive deficits associated with CU traits. Participants were randomized to parent training versus parent training plus a child-focused emotion recognition training (ERT) component. The ERT component was based on the Mindreading program originally developed to train children with autism to accurately identify and interpret emotional expressions in interpersonal contexts (Baron-Cohen et al. 2004). This component was delivered to families through a combination of four (90 min) child and parent–child sessions involving

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interactive computerized modules and homework in the form of parent–child emotion-focused games that were manualized for the purposes of the study. Parent training alone was not associated with a decrease in conduct problems in this sample as a whole (Dadds et al. 2012b). This was understood to reflect in part the chronic problems of the population from which participants were sampled and is perhaps not surprising considering the upper age range of participants. However, consistent with the notion that CU traits are associated with risk for poor treatment outcomes, children/adolescents with high levels of CU traits demonstrated an increase in conduct problems across the 6-month follow-up, while those with low levels of CU traits showed no such amplification. In addition to operating as a predictor of poor treatment outcomes, CU traits were also found to moderate effects associated with the ERT intervention. The combination of ERT plus parent training was found to significantly enhance treatment outcomes beyond those associated with parent training alone, but only for participants with CU traits. That is, children and adolescents with high levels of levels of CU traits who received the novel intervention showed a significant reduction in conduct problems at 6-month follow-up, while those with low levels of CU traits showed no significant improvement. Evidence relating CU traits to poor treatment outcomes has also been reported in two studies by Masi and colleagues. Both studies involved clinic-referred participants aged (6–14 years) whose conduct problems were treated with lengthy multimodal intervention based on MST. In the first of these studies, Masi et al. (2011) found that participants categorized as non-responders following a 6-month intervention exhibited higher levels of CU traits than responders. However, this effect was no longer significant when post hoc corrections were applied. In a larger sample (n = 118) followed up across a 12-month intervention, Masi et al. (2013) subsequently found that CU traits significantly predicted non-responder status, independent of severity of conduct problems pre-treatment. Two studies involving family based interventions with child-focused components have reported results that challenge the notion that CU traits are associated with poor treatment outcomes. Kolko and Pardini (2010) examined predictors of treatment outcomes among children (6–11 years) diagnosed with ODD or CD, who were randomized to a modular intervention (parent and child skills training, medication, school consultation), or TAU in community health settings. Teacher-reported CU traits were not found to predict long-term (3 year) outcomes with respect to overall conduct problem symptoms. However, CU traits were implicated in two paradoxical findings related to participant outcomes. First, the most robust predictor of overall conduct problems was the ‘hurtfulness’

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dimension of ODD (as indexed by the diagnostic feature ‘‘often spiteful or vindictive’’). Epidemiological research into the structure of ODD has indicated that this dimension may indeed be a marker for CU traits (for review see Frick and Nigg 2012). Surprisingly, Kolko and Pardini (2010) found that this hurtfulness dimension was not associated with the teacher-reported measure of CU traits that was used. Whether this reflects measurement limitations associated with these teacher data, or whether CU traits may be less related to hurtfulness than currently thought, is difficult to determine. Second, for one outcome measure—ODD symptoms—higher levels of CU traits were associated with greater improvement. Given that this effect was specific to ODD symptoms, it may be that during the long-term (3 year) follow-up period, participants with CU traits underwent a developmental shift associated with decreases in the emotional symptoms that comprise the irritability dimension of the disorder, as opposed to treatment-related change in these symptoms. White et al. (2013) examined treatment response among adolescents (11–17 years) who were court-ordered to attend Functional Family Therapy as part of a juvenile justice diversion program. CU traits were found to be associated with a number of treatment-related variables; however, these associations varied considerably depending on whether or not analyses controlled for pre-treatment severity of conduct problems. CU traits were found to be associated with greater improvement in conduct problems, but only in analyses that did not control for conduct problem severity at pretreatment. When controlling for pre-treatment severity of conduct problems, CU traits were not associated with change in conduct problems across treatment. Furthermore, when controlling for baseline conduct problems severity, CU traits were significantly associated with increased violent offending across treatment according to official records of offences, and a perceived lack of change according to youth reports (but not those of parents or therapists). As such, although somewhat limited associations between CU traits and treatment outcomes were apparent in this sample, the only associations that were shown to be independent of baseline conduct problems indicate a risk for poor outcomes among youths with CU traits (White et al. 2013). Parent and Child Therapy: Processes Findings regarding CU traits and attendance/dropout in interventions with parent and child components have been mixed. Dadds et al. (2012) found that participants who dropped out had higher levels of CU traits than those who did not, while other studies have found no association between CU traits and rates of participation or dropout

Clin Child Fam Psychol Rev Table 3 Findings pertaining to clinical change in CU traits Study

Treatment outcomes

Treatment processes

Main methodological limitations

Butler et al. (2011)

Adolescents randomised to MST showed a significant (medium effect sized) decrease in CU traits, whereas those allocated to usual services did not

Not reported

APSD total score (i.e., global CU traits plus CP) used to index CU traits

Hawes and Dadds (2007)

Sample showed a decrease in CU traits (medium effect size) following parent training, which was maintained across 6-months follow-up

Parent implementation of positive reinforcement and limit-setting skills not associated with stability of CU traits

Small sample size; singleinformant CU traits; no control group

Kolko et al. (2009)

Sample showed a decrease in CU traits (medium effect) following parent and child therapy, which was maintained across 3-year follow-up

Not reported

Single-informant (teacher) CU traits; no control group


CU traits did not decrease following MST or usual services

Not reported

Single-informant (parent) CU traits; no follow-up beyond post-treatment

McDonald et al. (2011)

Participants randomised to parent training showed decrease in CU traits (large effect size), while those allocated to services as usual did not

Effects of parent training on CU traits mediated by change in parents’ psychological aggression toward their child

Small sample size; singleinformant (parent) CU traits

Somech and Elizur (2012)

Children randomised to parent training showed a decrease in CU traits (large effect), whereas those in a minimal support condition exhibited increased in CU traits

Reductions in CU traits were mediated through improvements in harsh/ inconsistent parenting and parental distressa

All measures parent report

CP conduct problems, CU callous-unemotional traits, MST multi-systemic therapy, APSD antisocial process screening As reported in personal communication cited by Waller et al. (2013)

a

(Hawes et al. 2013; White et al., 2013). The only study to report on broader aspects of therapeutic process was that of Dadds et al. (2012), in which mediation analyses were used to examine mechanisms of change associated with the novel ERT intervention. These analyses pointed to somewhat surprising change processes. Surprisingly, despite the enhanced treatment outcomes among youths with high levels of CU traits who received the ERT intervention, ERT was not associated with change in the specific emotion recognition skills that were targeted. Furthermore, although the effects of ERT on conduct problems were accounted for in part by improvements in children’s affective empathy, ERT was also found to produce change in conduct problems independent of change in empathy. Based on the clinical processes through which ERT was delivered, we speculated that the intervention may have inadvertently acted on warmth in the parent–child relationship. That is, by embedding the skills training in emotion-focused parent–child activities, ERT may have operated less on compensatory skills related to children’s self-regulation and more on family processes of unique importance to children with CU traits (Dadds et al. 2012b). Clinical Change in CU Traits We located six studies in which child and adolescent CU traits have been examined as an outcome variable following family based intervention. The key findings and limitations of these studies are summarized in Table 3. Three of the

studies involved parent training interventions in which children played no active role in therapy (Hawes and Dadds 2007; McDonald et al. 2011; Somech and Elizur 2012), whereas three investigated interventions in which components were delivered directly to both children and their parents (Butler et al. 2011; Kolko et al. 2009; Manders et al. 2013). Parent Training Interventions: Outcomes Change in CU traits following parent training were first investigated by Hawes and Dadds (2007), using the sample of boys (aged 4–8 years) with ODD originally reported on by Hawes and Dadds (2005b). Across pre- to post-treatment, this sample demonstrated a mean drop in CU traits in the order of a medium effect size (Cohen’s d = 0.49), which was maintained across the 6-month follow-up. Analyses also indicated that the poorest treatment outcomes occurred for those boys who demonstrated the most stable patterns of high-CU traits. Additionally, consistent with the notion that CU traits and conduct problems are associated with distinct change processes, follow-up levels of CU traits and conduct problems were found to be predicted by distinct baseline variables. Given the absence of a non-treatment control group in this study, clear conclusions could not be drawn regarding the impact of treatment on CU traits. However, available data indicated that reductions in CU traits were not simply accounted for by the over-reporting of CU traits

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pre-treatment due to factors such as parental stress or depression. Two subsequent studies used RCT designs to examine CU traits as an outcome following parent training, thereby allowing the influence of social-learning-based intervention on CU traits to be differentiated from alternative (e.g., maturational) processes that may also give rise to change in this domain. McDonald et al. (2011) recruited high-risk families of children (aged 4–9 years) diagnosed with ODD from a domestic violence shelter, and randomized them to either a lengthy (20 session) parent training intervention or services as usual. Children who received parent training showed a significant decrease in CU traits, while those allocated to services as usual did not. Additionally, while levels of CU traits remained stable in the parent training condition, comparison children exhibited significant increases in CU traits across a 20-month follow-up period. The reductions in CU traits associated with parent training were large in effect size, both from baseline to post-treatment (Cohen’s d = 0.85) and from baseline to the final follow-up (Cohen’s d = 0.76). Significant improvements in ODD symptom severity were also observed, and consistent with the preliminary findings of Hawes and Dadds (2007), change in CU traits was found to be independent of change in those symptoms. Somech and Elizur (2012) examined change in CU traits following a 14-session social-learning-based parent training program delivered to small groups of 5–7 couples. Families of children (aged 2–5 years) with clinically significant conduct problems referred by pre-kindergarten teachers were randomized to this intervention (n = 96) versus a minimal support control group (n = 29). Intention to treat analyses showed decreases in the order of a large effect size for CU traits in the parent training condition (Cohen’s d = 0.85), which were maintained at 1-year follow-up. Conversely, children in the control condition exhibited significant increases in CU traits across this period. Using the reliable change index method (Jacobson and Truax 1991), 23.2 % of cases exhibited reliable improvements in CU traits following parent training, compared to only 5.26 % in the control condition (Somech and Elizur 2012). Interestingly, parent training was found to produce similar changes (improvements) in children’s effortful control. In this study, effortful control was assessed using parent reports on the Children’s Behaviour Questionnaire (Rothbart et al. 2001), wherein the construct is operationalised in terms of behaviors pertaining to inhibitory control, attention focusing, and attention shifting. The findings of Somech and Elizur (2012) therefore add to growing evidence that family based intervention has the potential to impact on child characteristics commonly conceptualized in terms of biologically based temperament.

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Parent Training Interventions: Processes Findings regarding associations between domains of parenting targeted in treatment, and change in CU traits, have been reported for all three of the parent training studies reviewed here. Hawes and Dadds (2007) compared boys grouped according to the temporal stability of their CU traits on parental implementation of the positive reinforcement and limit-setting skills introduced in treatment. Parent reports and observational coding of family interactions indicated no association between CU traits and the frequency or quality of this implementation, despite the finding that boys characterized by the most stable patterns of CU traits were those most likely to retain a diagnosis of ODD. As such, parenting practices did not appear to be related to the stability of CU traits in this sample. Evidence regarding mechanisms of change in CU traits is available from both of the RCT parent training studies; however, the results of mediation analyses are somewhat mixed with respect to the role of parenting variables. Somech and Elizur (2012) found that reductions in CU traits were mediated through improvements in self-reported harsh/inconsistent parenting and parental distress (see personal communication cited by Waller et al. 2012). In contrast, McDonald et al. (2011) found that although harsh (physical aggression) and inconsistent, parenting-mediated change in Psychopathy Screening Device Total scores (i.e., global CU traits and conduct problems), change in these parenting variables did not account for change in CU traits subscale scores. The only parent variable found to mediate improvements in CU traits specifically was psychological aggression toward the child (McDonald et al. 2011). Compared to the other parenting variables tested that of psychological aggression toward a child (e.g., threats, rejection) can be seen as more conceptually related to the dimension of parental warmth/rejection than inconsistent or physically aggressive parenting (Hawes and Dadds 2013). The data reported by McDonald et al. (2011) therefore add further support to the notion that parental warmth is of unique importance to the development of children with CU traits. However, as it is the only parent training study to examine such a variable to date, replication of this finding is needed. Parent and Child Therapy: Outcomes and Processes Data on change in CU traits following intervention involving both child and parent components were first reported by Kolko et al. (2009). This change was examined in the sample of children (aged 6–11 years) discussed already in relation to predictors of change in conduct problems (Kolko and Pardini 2010). The CU traits of children in this sample, as indexed by teacher report,


demonstrated a decrease in the order of a medium effect size (pre- to post-treatment: Cohen’s d = 0.44). This change was shown to be independent of treatment parameters such as the child’s receipt of medication for comorbid ADHD. Importantly, this change in CU traits from pre- to post-treatment was maintained across the 3-year follow-up period (pre-treatment to follow-up: Cohen’s d = 0.48). However, in the absence of a non-treatment control group, it was not possible to distinguish the effects of treatment versus maturation on CU traits (Kolko et al. 2009). Change in CU traits has been examined in two studies involving randomization of participants to a family based intervention versus treatment as usual. The intervention examined in both of these studies was MST, delivered across a period of approximately 6 months. Butler et al. (2011) found that adolescents (aged 13–17 years) in receipt of MST showed a significant decrease in CU traits, as operationalized by Antisocial Process Screening Device Total scores, whereas those allocated to usual services did not. This decrease was of a medium effect size (Hedges g = 0.53) and seen only for parent-reported ASPD scores. Youth-report CU traits showed no change across treatment. In contrast, Manders et al. (2013) found that parentreported CU traits did not significantly decrease from preto post-treatment among adolescents (aged 12–18 years) who received MST or services as usual. Despite close similarities in the design of these two studies, comparison is complicated by the divergent approaches used to measure CU traits. Manders et al. (2013) indexed CU traits using ICU scores, thereby raising the possibility that the change in APSD total scores reported by Butler et al. (2011) reflected change in impulsive conduct problems rather than CU traits per se. However, this interpretation seems at odds with the lack of any significant change in APSD subscales scores for impulsive conduct problems reported by Manders et al. (2013). In any case, evidence that CU traits respond to family based intervention during adolescence is at present particularly limited and mixed. Furthermore, among the studies that have examined CU traits as an outcome of interventions with parent and child components (Butler et al. 2011; Kolko et al. 2009; Manders et al. 2013), none report on CU traits in relation to process variables or mechanisms of change.

Discussion Are CU Traits Related to Treatment Outcomes? The first major question of this review was whether CU traits are associated with increased risk for poor outcomes following family based intervention for conduct problems. Evidence of this risk has now been reported in nine

treatment outcome studies, or 81 % of the studies that have addressed the question to date. As such, it is clearly apparent that pre-treatment data on CU traits are clinically informative with respect to the prognostic status of children and adolescents referred for treatment of conduct problems. For the most part, these studies have relied on single treatment condition designs in which the presence of CU traits has been tested as a predictor, or prognostic indicator, of treatment outcomes. However, the two studies to date in which pre-treatment CU traits have been tested as a moderator of response to family based treatment for conduct problem both found support for such an effect (Dadds et al. 2012b; Manders et al. 2013). The findings of these studies can be seen to converge with emerging evidence from treatment outcome research into other child characteristics. For example, the emotionally dysregulated temperament that is thought to characterize low-CU children with conduct problems (Frick and Morris 2004) has recently been associated with increased responsiveness to parent training (Scott and O’Connor 2012). A number of more specific inferences concerning CU traits and clinical change in conduct problems are also supported. First, it is apparent that the reduced treatment response among individuals with CU traits is not simply a by-product of diagnostic characteristics that may covary with CU traits. Although CU traits are consistently associated with increased severity of conduct problems at pretreatment, this is not the reason that children with high-CU traits demonstrate poorer outcomes than their low-CU counterparts. Likewise, research with highly comorbid samples has found the association between CU traits and treatment response to be independent of other features of psychopathology that share phenotypic overlap with CU traits, including autism spectrum disorders (e.g., Hawes et al. 2013). Second, despite CD being the only diagnostic category that makes mentions of CU traits in DSM5, it is clear that the risk for poor treatment outcomes associated with CU traits is by no means specific to individuals with this disorder. Indeed, there is more evidence of this risk among individuals with ODD than among those with CD. Of the studies in which diagnostic symptoms have been reported, all have been conducted with either samples characterized by ODD or comprising participants diagnosed with both ODD and CD. Interestingly, the only intervention study to have investigated CD symptoms specifically is one of the only studies in which CU traits were not associated with poor treatment outcomes (Kolko and Pardini 2010). Third, associations between CU traits and treatment outcomes are not easily explained by family processes associated with the acquisition or implementation of parenting skills. Observational and self-report data on parenting indicate that CU traits do not moderate change in

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parents’ skills across treatment and that CU traits predict clinical outcomes when controlling for individual differences in these skills (Hawes and Dadds 2005b; Ho¨gstro¨m et al. 2013). Additionally, clinical risk associated with CU traits does not appear to be explained by family factors that might be associated with the biased over-reporting of CU traits. Poor treatment outcomes have been associated with CU traits when controlling for parental stress, depression, and socioeconomic disadvantage (e.g., Hawes and Dadds 2007). This effect has also been demonstrated using multiinformant indices of CU traits based on data provided by mothers, fathers, teachers, and youth, and replicated across informants (e.g., Hawes and Dadds 2005b; Dadds et al. 2012b). Fourth, CU traits appear to predict poor outcomes across both standardized parent training interventions and more individualized interventions comprising both parent and child components. Although findings across studies are not entirely consistent, they are nonetheless at odds with the notion that interventions targeting both parent and child competencies are sufficient to overcome the clinical risk associated with CU traits. For example, CU traits have been shown to moderate response to MST—an evidencebased intervention characterized by a particularly comprehensive, formulation-driven approach involving both parent and child targets (Manders et al. 2013). Do CU Traits Respond to Family based Intervention? The second major question of this review was whether family based intervention is capable of producing meaningful change in CU traits. Four studies to date have examined this question using RCT designs (Butler et al. 2011; Manders et al. 2013; McDonald et al. 2011; Somech and Elizur 2012), three of which found reductions in CU traits that could be attributed to the effects of intervention. It should be noted, however, that only two of the positive RCTs—both conducted with early-childhood samples (McDonald et al. 2011; Somech and Elizur 2012)— indexed CU traits specifically, as opposed to global levels of psychopathy comprising both CU traits and general conduct problems. This evidence adds to earlier findings of durable change in CU traits following family based treatment, as indexed by both parent and teacher reports (Hawes and Dadds 2007; Kolko et al. 2009). It is also consistent with emerging evidence regarding the contributions of family environment to other domains of child psychopathology that demonstrate strong neurobiological underpinnings, such as ADHD (e.g., Hawes et al. 2013 Martel et al. 2011). Available evidence raises further questions regarding the potential importance of treatment dose and child age. During early childhood, parent training interventions

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delivered in between 10 and 20 sessions have been associated with change in CU traits in the order of large effect size (McDonald et al. 2011; Somech and Elizur 2012). In middle-to-late childhood, the effect size reported for change in CU traits following *20 weekly sessions has been medium only (Kolko et al. 2009). This would suggest that existing brief parent training interventions may produce maximal change in CU traits when delivered early in childhood. Such a perspective would seem consistent with current evidence regarding early intervention and developmental cascades (e.g., Masten and Cicchetti 2010). Methodological Considerations and Recommendations As outlined in Tables 2 and 3, interpretations of studies in this field have at times been complicated by a range of methodological limitations. Many of these limitations (e.g., small sample size, a lack of comparison conditions, a lack of measures addressing treatment processes and tests of change mechanisms) are shared by much research into predictors and moderators of treatment outcomes in other clinical populations. Other methodological issues may present limitations of more unique importance to research questions related to clinical change among children with CU traits. Two such issues are particularly noteworthy. First, based on the established covariation between CU traits and conduct problems, it is critical to control for pretreatment severity of conduct problems when examining the association between CU traits and conduct problems following treatment. Likewise, tests of clinical change in CU traits stand to be most informative when they establish whether such change is independent of change in conduct problems. Second, based on the conceptualization of CU traits as a set of characteristics that are stable across context, multi-informant reports of a child’s CU traits are most likely to reflect the core construct of interest. Such measurement remains particularly limited in the treatment outcome literature and should therefore be of high priority in future research. Given the range of methodological limitations that have characterized studies to date, it is important to consider whether variation in study quality may account for the mixed findings that have at times been published. There do not appear to be specific methodological issues that distinguish studies that have reported significant associations between CU traits and clinical change in conduct problems from those that have not. However, when studies are grouped based on key features of methodological rigor, results are highly consistent. For example, each of the studies that have examined multi-informant measures of pre-treatment CU traits when controlling for conduct problem severity have found them to be adversely associated with treatment outcomes, as have each of the studies


that have examined the occurrence of pre-treatment CU traits as a moderator of treatment outcomes among participants randomized to distinct conditions. What Clinical Strategies are Indicated for Children with CU Traits? A number of tentative conclusions can be made regarding the therapeutic strategies that may be most likely to benefit children with CU traits. First and foremost, there is good reason to believe that the best starting point for treatment planning is current interventions for conduct problems based on social learning theory. Although the effectiveness of these interventions appears to be reduced for children with CU traits, clinically significant gains may nonetheless result. For example, we recently found that although children with high levels of CU traits were twice as likely as low-CU children to retain diagnosable levels of ODD 6 months following parent training, the majority of highCU children shifted out of a diagnostic range (Hawes et al. 2013). Furthermore, given that existing forms of these interventions have been found to produce change in CU traits (e.g., McDonald et al. 2011), it is likely that such effects may be enhanced through the addition of adjunctive components designed to explicitly target deficits related to CU traits. Second, components that focus on positive reinforcement (reward) strategies and the promotion of warmth in the parent–child relationship may be particularly indicated. The behavior of children with CU traits appears to be more responsive to positive reinforcement than punishment (e.g., Hawes and Dadds 2005b). Additionally, parental warmth appears to be more proximal than harsh/inconsistent discipline to the conduct problems of high-CU children (e.g., Pasalich et al. 2011). Furthermore, the key mechanism accounting for clinical change in CU traits following parent training appears to concern changes in psychological aggression—a domain of parenting characterized by rejection and a lack of parental warmth (McDonald et al. 2011). For such children, interventions that prioritize targets related to positive reinforcement and parental warmth therefore appear best placed to achieve optimal change with respect to conduct problems as well as CU traits. Importantly, however, we believe that a focus on warmth and positive parenting should not come at the expense of equipping parents with limit-setting strategies for managing misbehavior (e.g., time out). Evidence examined in this review might prompt some clinicians to treat children with CU traits using interventions based exclusively on the promotion of positive parenting and relational warmth. In our view, this may be counter-therapeutic. Not only have CU traits been associated with child-driven effects on increases in harsh and inconsistent discipline across

childhood (e.g., Hawes et al. 2011), but such parenting has been associated with increases in CU traits over time (e.g., Waller et al. 2012). Parents who are not equipped with nonforceful strategies for setting limits on child behavior may therefore be at risk for developing increasingly negative parenting practices that may in turn feedback into the CU traits of predisposed children. Novel Interventions for Children with CU Traits Very little has been written about the development of interventions that may better meet the unique needs of children and adolescents with CU traits. Recently emerging literature has, however, indicated a range of future directions for such work, including the modification of existing parent training interventions (Kimonis and Armstrong 2012), as well as youth-focused cognitive interventions (Salekin et al. 2012), and school-based programs (Frederickson et al. 2013). Our own work on the development of such interventions has been driven by models of the neurocognitive deficits that characterize these children. Of key interest has been evidence that children with CU traits show deficits in the allocation of attention to critically salient aspects of the environment and that like patients with amygdala damage (e.g., Adolphs et al. 2005), highCU children are able to overcome their ‘fear blindness’ when they are directed to ‘‘look at the eyes’’ of faces (Dadds 2006, Dadds et al. 2008). Our initial attempt to develop a targeted intervention for this population took the form of a computer-based emotion recognition training program (Dadds et al. 2012b). To date, this remains the only RCT to have tested whether the effectiveness of parent training for conduct problems can be enhanced for such participants by delivering it in combination with adjunctive components targeting socialcognitive deficits associated with CU traits. As noted already, this novel intervention was found to enhance the treatment outcomes of participants with high levels of CU traits. However, this effect was not mediated by change in the specific social-cognitive competencies that were targeted, leading us to reflect on the family based mechanisms (e.g., enhanced emotional engagement) through which the intervention may have inadvertently conferred benefits to these participants. Our group has therefore moved away from computer-based interventions and those that focus on emotional attention in contexts that are removed from realworld attachment figures. We now believe that therapeutic gains for high-CU children will most likely arise from shifts in emotional engagement between these children and their parents, as operationalized by behavior such as reciprocal eye contact. Eye contact is critical to understanding the emotional state of the other and is critical for the healthy development of

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conscience, empathy, and social competence (see Skuse et al. 2003). Any impairment in this attentional reflex is likely to interfere with parent–child bonding and to deprive the child of critical information about the consequences of his or her behavior on other people. We thus hypothesize that the failure to make eye contact with attachment figures that appears to be characteristic of children with CU traits not only reduces the influence of parenting and attachment processes, but leads to a series of cascading errors affecting the development of empathy and social functioning (Dadds et al. 2011). We propose that there are at least three mechanisms by which the remediation of deficits in reciprocated eye contact may improve the effectiveness of parent training interventions for conduct problems among young children with CU traits. First, in the short term, increased eye contact between the parent and child is predicted to increase the quality of the relationship, and the potential for parental responses to function as motivating rewards for prosocial behavior (Wahler and Meginnis 1997). Second, such remediation may potentially increase the child’s attention to the emotional content of parental instructions and in turn improve child responses to parental limit setting. Third, we predict that in young children, increases in healthy eye contact may initiate cascading neuropeptide (e.g., oxytocin: Ross and Young 2009) and connectionist changes (e.g., amygdala to higher processing circuitry; Blair 2003; Viding et al. 2012) that increase the salience of emotional stimuli to these children and facilitate a normalization of dysfunctional neural systems over time (Shaw et al. 2004; Skuse et al. 2003). Intervention studies are needed to establish the efficacy of clinical strategies based on these predictions. We have developed an adjunctive ‘‘Emotional Engagement’’ (EE) intervention comprising a brief series of structured in vivo parent–child interactions focused on the promotion of shared eye contact, that is designed to be used in conjunction with our standard parent training program (Hawes and Dadds 2006). This EE intervention is designed to be delivered using Video Interactive Guidance (VIG: Fukkink 2008), in which parents are provided with positive and negative feedback and specific goals set for future interactions. These interactions are implemented during ‘compliance’ situations, wherein emotional engagement and eye contact is used to promote the child’s attention to parental communication, as well as during reading, story-telling, and casual conversation (e.g., in the bedtime routine), for the purpose of promoting reciprocated emotional engagement and growth of positive relationships. Our team has commenced research in Sydney and London using randomized controlled trials and a series of single case experimental designs in which repeated observations of parent–child interactions are collated using a staggered multiple baseline design (Barlow and Hersen 1984), and

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data on clinical change in these processes will be available in the near future.

Conclusions There are now 11 studies that report on clinical change in conduct problems among children with CU traits following family based intervention. Unique associations between CU traits and poor treatment outcomes are identified in the clear majority of studies that can be brought to bear on the topic. Likewise, the six studies that have examined CU traits as a treatment outcome have provided compelling evidence that social-learning-based parent training is capable of producing lasting improvement in CU traits, particularly when delivered early in childhood. It is important to note that the conclusions of this review are limited by potential biases related to selective reporting in this literature, such as the ‘file drawer problem’ whereby nonsignificant results often remain unpublished. Additionally, the studies that have been conducted to date have varied considerably with respect to methodology (e.g., design, measurement, age range) and in turn, quality. The findings of these studies do not presently appear to vary as a function of study methodology or quality, yet the interpretation of mixed findings in this literature has at times been complicated by this issue. Among the various designs that have been used to examine the treatment outcomes of children with CU traits, those that have allowed for tests of moderation have been particularly few in number, as have those in which CU traits have been indexed through multi-informant measurement, and those in which data on therapeutic processes have been collected. Further research of this kind is clearly needed. Notwithstanding this, it is apparent that the clinical needs of children with conduct problems and CU traits warrant intervention strategies beyond those included in current evidencebased interventions. We predict that adjunctive treatment components that target precise aspects of parent–child emotional engagement (e.g., eye contact) hold the potential to enhance parent training outcomes among these children and believe that theory-driven research into such interventions should be made a priority. Acknowledgments We are grateful to the authors of the reviewed studies who provided us with additional information about those studies and to the anonymous reviewers who provided valuable feedback on an earlier draft of this manuscript.

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Conduct Problems in Childhood and Adolescence: Developmental Trajectories, Predictors and Outcomes in a Six-Year Follow Up.

Narcissism and Callous-Unemotional Traits Prospectively Predict Child Conduct Problems.

Early Childhood Trajectories of Conduct Problems and Callous-Unemotional Traits: The Role of Fearlessness and Psychopathic Personality Dimensions.

Developmentally dynamic genome: Evidence of genetic influences on increases and decreases in conduct problems from early childhood to adolescence.

The longitudinal relation between childhood autistic traits and psychosexual problems in early adolescence: The Tracking Adolescents' Individual Lives Survey study.

Gender Differences in the Developmental Links Between Conduct Problems and Depression Across Early Adolescence.

Measures of circadian preference in childhood and adolescence: A review.

Effects of Callous-Unemotional Traits on the Association Between Parenting and Child Conduct Problems.

Anxiety disorders of childhood and adolescence: a critical review.

hyperactivity disorder (ADHD).

Treatment of attentional and hyperactivity problems in children with sympathomimetic drugs: a comprehensive review.

Problems and treatment of drug abuse in adolescence.

Examining the concurrent and longitudinal relationship between diurnal cortisol rhythms and conduct problems during childhood.

Cognitive ability and psychopathic traits: independent and interactive associations with youth conduct problems.

Refining the parent-reported inventory of callous-unemotional traits in boys with conduct problems.

inattention and conduct problems in a South Korean twin sample.

Aggression and Rule-breaking: Heritability and stability of antisocial behavior problems in childhood and adolescence.

Treatment of Hodgkin's lymphoma in childhood and adolescence without radiotherapy.

The end of mentally handicapped childhood: problems of residential transfer and school leaving during adolescence.

Externalizing behavior problems and academic underachievement in childhood and adolescence: causal relationships and underlying mechanisms.

adolescence.

The development of personality extremity from childhood to adolescence: relations to internalizing and externalizing problems.

Childhood behaviour problems predict crime and violence in late adolescence: Brazilian and British birth cohort studies.

[Childhood and adolescence program].