Low Callous-unemotional Traits Research Articles

Cortical structure and subcortical volumes in conduct disorder: a coordinated analysis of 15 international cohorts from the ENIGMA-Antisocial Behavior Working Group

Conduct disorder is associated with the highest burden of any mental disorder in childhood, yet its neurobiology remains unclear. Inconsistent findings limit our understanding of the role of brain structure alterations in conduct disorder. This study aims to identify the most robust and replicable brain structural correlates of conduct disorder. The ENIGMA-Antisocial Behavior Working Group performed a coordinated analysis of structural MRI data from 15 international cohorts. Eligibility criteria were a mean sample age of 18 years or less, with data available on sex, age, and diagnosis of conduct disorder, and at least ten participants with conduct disorder and ten typically developing participants. 3D T1-weighted MRI brain scans of all participants were pre-processed using ENIGMA-standardised protocols. We assessed group differences in cortical thickness, surface area, and subcortical volumes using general linear models, adjusting for age, sex, and total intracranial volume. Group-by-sex and group-by-age interactions, and DSM-subtype comparisons (childhood-onset vs adolescent-onset, and low vs high levels of callous-unemotional traits) were investigated. People with lived experience of conduct disorder were not involved in this study. We collated individual participant data from 1185 young people with conduct disorder (339 [28·6%] female and 846 [71·4%] male) and 1253 typically developing young people (446 [35·6%] female and 807 [64·4%] male), with a mean age of 13·5 years (SD 3·0; range 7-21). Information on race and ethnicity was not available. Relative to typically developing young people, the conduct disorder group had lower surface area in 26 cortical regions and lower total surface area (Cohen's d 0·09-0·26). Cortical thickness differed in the caudal anterior cingulate cortex (d 0·16) and the banks of the superior temporal sulcus (d -0·13). The conduct disorder group also had smaller amygdala (d 0·13), nucleus accumbens (d 0·11), thalamus (d 0·14), and hippocampus (d 0·12) volumes. Most differences remained significant after adjusting for ADHD comorbidity or intelligence quotient. No group-by-sex or group-by-age interactions were detected. Few differences were found between DSM-defined conduct disorder subtypes. However, individuals with high callous-unemotional traits showed more widespread differences compared with controls than those with low callous-unemotional traits. Our findings provide robust evidence of subtle yet widespread brain structural alterations in conduct disorder across subtypes and sexes, mostly in surface area. These findings provide further evidence that brain alterations might contribute to conduct disorder. Greater consideration of this under-recognised disorder is needed in research and clinical practice. Academy of Medical Sciences and Economic and Social Research Council.

The role of threat sensitivity, social affiliation, and left-behind experience in shaping adolescent callous-unemotional and borderline personality traits

Exploring callous-unemotional (CU) and borderline personality disorder (BPD) traits during adolescence is crucial due to its role in the emergence of personality pathologies. Recent research highlights threat sensitivity and social affiliation as fundamental factors in the etiology of broader interpersonal dysfunctions in personality disorders. Further studies are needed to explore the contributions of these factors to CU and BPD traits, while considering specific parental risk factors within distinct cultural contexts. This study examines the effects of threat sensitivity, social affiliation, and left-behind experience (LBE) on CU and BPD traits in 563 Chinese adolescents. We found that the interaction between threat sensitivity and social affiliation significantly predicts CU traits in adolescents without LBE, where reduced social affiliation amplifies the association between low threat sensitivity and CU traits. Conversely, LBE and a strong need for social affiliation intensify the association between increased threat sensitivity and BPD traits. These findings highlight the specific contributions of dispositional factors to CU and BPD traits, offering insights into their divergent pathways. By elucidating the nuanced interplay of dispositional and parental risk factors, this study enhances our understanding of the predictors of adolescent personality disorders and emphasizes the need for targeted interventions tailored to these dynamics.

Deficits in emotion recognition and processing in children with high callous-unemotional traits: the role of the MAOA gene

Children with high Callous-Unemotional (CU) traits show deficits in recognizing and processing facial expressions. Alterations in emotion recognition have been linked to a higher synaptic concentration of monoaminergic neurotransmitters. The current study investigated the relationship between the MAOA-Low-activity alleles and the ability to recognize and process facial expressions in 97 male children (8–12 years old) diagnosed with disruptive behavior disorder. Participants completed a computerized emotion-recognition task while an eye-tracking system recorded the number (Fixation Count, FC) and length (Fixation Duration, FD) of fixations to the eye region of the emotional stimuli. Children with high CU traits exhibited lower scores in recognition of sadness and anger, and lower FC and FD for sadness and fear than children with low CU traits. Children carrying the MAOA-Low-activity alleles displayed lower FD for sadness, and FD and FC for fear than those carrying the MAOA-High-activity alleles. These genetic effects appeared even stronger in children with CU traits. Moderation analysis revealed that CU traits were associated with lower FC and FD for fear, and lower FD for sadness, probably due to the MAOA-Low-activity alleles. Our findings, although to be replicated, suggest MAOA-Low-activity alleles as potential genetic biomarkers to identify CU children in need of training focused on emotion processing.

Examining the relation among callous-unemotional traits and cortisol, alpha-amylase, and testosterone reactivity in legal system involved young men

Elevated callous-unemotional (CU) traits (e.g., lack of empathy, deficient guilt/remorse, and shallow affect) are associated with increased antisociality and distinct patterns of cognitive and emotional functioning. Previous investigations have suggested that deficits in physiological stress responses may underlie these associations, yet few studies simultaneously examine the multiple physiological systems responsible for mounting a stress response. To clarify how individuals with and without elevated CU traits respond to acute stress, the current study examined the association between CU traits and hormones released by three systems: cortisol from the hypothalamic-pituitary-adrenal (HPA) axis, alpha-amylase from the sympathetic nervous system (SNS), and testosterone from hypothalamic-pituitary-gonadal (HPG) axis. Specifically, we used fixed effect regression modeling to examine within-individual changes in each biomarker across the administration of a standardized laboratory stressor (Trier Social Stress Test) in a sample of 55 justice-involved young men (Mage= 22.84). Results indicated significant within-individual changes in cortisol, alpha-amylase, and testosterone following the stressor among those with low or average CU traits. However, those with high levels of CU exhibited no significant changes in their cortisol and testosterone levels. Furthermore, individuals with high CU traits exhibit an asymmetric stress response, such that alpha-amylase and testosterone levels were not associated with changes in cortisol levels. In sum, elevated CU traits were associated with blunted cortisol and testosterone reactivity and asymmetric response to stress. Additional work is needed to determine the behavioral and treatment implications of this distinct stress response.

Resting-state connectivity underlying cognitive control's association with perspective taking in callous-unemotional traits

Callous-Unemotional (CU) traits are often associated with impairments in perspective taking and cognitive control (regulating goal directed behavior); and adolescents with CU traits demonstrate aberrant brain activation/connectivity in areas underlying these processes. Together cognitive control and perspective taking are thought to link mechanistically to explain CU traits. Because increased cognitive control demands modulate perspective taking ability among both typically developing samples and individuals with elevated CU traits, understanding the neurophysiological substrates of these constructs could inform efforts to alleviate societal costs of antisocial behavior. The present study uses GIMME to examine the heterogenous functional brain properties (i.e., connection density, node centrality) underlying cognitive control's influence on perspective taking among adolescents on a CU trait continuum. Results reveal that cognitive control had a negative indirect association with CU traits via perspective taking; and brain connectivity indirectly associated with lower CU traits – specifically the social network via perspective taking and conflict network via cognitive control. Additionally, less negative connection density between the social and conflict networks was directly associated with higher CU traits. Our results support the growing literature on cognitive control's influence on socio-cognitive functioning in CU traits and extends that work by identifying underlying functional brain properties.

Facial reactions to emotional films in young children with conduct problems and varying levels of callous-unemotional traits.

Elevated levels of callous-unemotional (CU) traits have proven useful for identifying a distinct subgroup of children whose conduct problems (CP) are early emerging, severe, persistent, and underpinned by aberrant emotional processing. The early childhood emotional experiences and expressions of CP subtypes are poorly understood, despite their importance to understanding the problematic attachments and atypical social affiliation experienced by children with elevated CU traits. The current study aimed to test for differences in facial emotional reactions to mood-inducing film clips in children with CP and varying levels of CU traits. We compared facial emotional reactions during a developmentally appropriate mood induction task in a mixed-sex sample of clinic-referred preschool children (Mage = 3.64 years, SD = 0.63, 66.9% male) classified as CP with elevated levels of CU traits (CP + CU; n = 25) versus low CU traits (CP-only; n = 47), and typically developing children (TD; n = 28). Relative to TD children, children with clinical CP showed less congruent and more incongruent facial emotional expressions to sad and happy film clips, controlling for child sex, age, and ethnicity. Consistent with older samples, young children with CP show atypical facial emotional expressions in response to positive and negative emotional stimuli. Findings have implications for developmental models of childhood antisocial behavior and can inform the development of targeted interventions.

Exposure to community violence and Callous-Unemotional traits in young children: the role of positive parenting

IntroductionStudies regarding environmental contributions on callous-unemotional (CU) traits in children have informed about the protective role of positive parenting. However, it has not been explored whether findings from these studies -mostly conducted in High-Income Countries- can be generalised to Low-Middle-Income Countries (LMICs). Exposure to community violence is common in LMICs and is associated with emotional and behavioural problems in children. Therefore, it may represent an environmental risk factor for CU traits.ObjectivesThis prospective study explores whether positive parenting has a protective role in relation to CU traits in young Colombian children whose families have been exposed to community violence.MethodsWe assessed 235 families with children at age 3.5 years, from three contrasting regions of Colombia, using observations of mother-child interactions and maternal reports of community violence at ages 3.5 and 5.0 years.ResultsHierarchical multiple linear regression models indicated that maternal positivity at 3.5 years was associated with lower CU traits at age 5.0 years only in children of families exposed to community violence (interaction term p= .001). In the exposed group maternal positivity explained 10% of the variance (β= -.34, p= .001) with low positivity associated with elevated CU traits and high positivity with low CU traits. Maternal praise was not associated with CU traits. However, maternal negativity during play was associated with elevated CU traits as a main effect.ConclusionsBased on these findings, whether or not exposure to community violence is associated with elevated CU traits depends on maternal positivity, with low positivity creating vulnerability, and high positivity, resilience.DisclosureNo significant relationships.

Warmth and reciprocity with mothers, and young children's resilience to exposure to community violence in Colombia: findings from the La Sabana Parent-Child Study.

Exposure to community violence is common worldwide and is associated with emotional and behavioural problems in children. Little is known about sources of resilience. Building on our previous work on the contribution of callous-unemotional (CU) traits to child aggression in Colombia, we examined whether positive parenting is protective for children whose families are exposed to community violence. Families were recruited from three demographically contrasting regions of Colombia. The sample comprised 235 children aged 3.5 years and their mothers, of whom 220 (93%) were followed up at age 5.0 years. Positive parenting was assessed as the average of maternal warmth and reciprocity, and as praise, and negative parenting as the average of negative affect and conflict seen in video recordings of standardized procedures. CU traits and oppositional defiant disorder were assessed by maternal report at ages 3.5 and 5.0 years, and mothers reported exposure to community violence over the 18 months between assessments. A range of potential confounds was included in adjusted analyses. In the families who were exposed to community violence, but not in the unexposed, maternal warmth and reciprocity were associated prospectively with lower CU traits (interaction, p = .007). In the exposed group maternal warmth and reciprocity explained 10% of the variance (β = -.34, p = .001). Maternal praise was not associated with CU traits. Maternal negative parenting predicted higher CU traits as the main effect but not in interaction with community violence exposure. Maternal warmth and reciprocity with young children may promote resilience in the face of community violence. Programmes to enhance these protective processes may be needed especially where prospects for reducing community violence are limited. The centrality of parents for these children highlights the plight of those exposed to community violence, and also either separated from parents or orphaned.

The Moderating Role of Maternal CU Traits in the Stability of Justice-Involved Adolescents’ CU Traits

ABSTRACT Objective Callous-unemotional (CU) traits are associated with chronic and severe antisocial behavior. Although previous research has found that parents play an important role in the etiology and maintenance of youth CU traits, little research has examined the extent that parents’ own CU traits impact the stability of their children’s CU traits. The present study investigated the moderating role of maternal CU traits on developmental changes in youth CU traits Method A sample of 346 mother-son dyads, in which all youth were justice-involved males (Mage = 15.81; 57.80% Latino, 20.52% White, 18.21% Black, 3.47% other race/ethnicity), across three states (California, Louisiana, and Pennsylvania) completed a semi-structured interview. Results Youth exhibited a decrease in CU traits over 30 months. Mothers’ CU traits moderated this relation, such that high maternal CU traits were associated with a smaller decrease in CU traits than low or average maternal CU traits, both when considering youth CU traits continuously and using a clinically significant cut score. The findings remained for continuous CU traits even after accounting for environmental factors (i.e., maternal warmth, maternal hostility, victimization, and witnessing violence), and these environmental factors did not vary over time. Conclusion The results highlight the importance of maternal influence in understanding how youth CU traits change over time, and have important implications for the use of parenting and family-level interventions among justice-involved youth.

Neural signatures of the development of antisocial behaviours and callous-unemotional traits among youth: The moderating role of parental support.

Comorbidity of antisocial behaviours (AB) and callous-unemotional (CU) traits characterizes a subgroup of youth at risk for chronic and severe AB in adulthood. Although aberrant neural response to facial emotion confers heightened risk for AB and CU traits, the behavioural effect of this neural response varies by family context. The present study examines the effects of neural response to emotional faces, parental support and the interaction between the two as predictors of AB and CU traits in a longitudinal sample of preadolescents (Nbaseline = 11,883; Mage = 9.5; 47.8% female). Low CU youth who evinced attenuated response to fearful faces within the left superior temporal sulcus and fusiform gyrus showed smaller decreases of AB over time; these associations did not extend to high CU youth. Among high CU youth reporting low parental support, blunted response to fearful faces within the bilateral inferior parietal sulcus predicted smaller decreases of AB. Study findings highlight neurobehavioural differences between youth with high and low CU traits, as well as the interacting roles of negative face processing and parental support in the development of AB.

Breaking the chains? The effects of training a shelter dog in prison on criminal behavior and recidivism

The effectiveness of Dutch Cell Dogs (DCD), a prison-based dog training program, in reducing criminal behavior and recidivism was assessed in a quasi-experimental study in twelve correctional facilities in the Netherlands (N = 241). DCD is a program in which incarcerated offenders train a shelter dog bi-weekly for eight weeks. Results demonstrated that DCD (n = 121) did not outperform treatment-as-usual (TAU; n = 120) in official recidivism outcomes and self-reported criminal behavior. However, subgroups based on age and detainees’ functioning responded differently in self-reported criminal behavior. Positive effects were found on self-reported criminal behavior for DCD participants who were older, had lower callous-unemotional traits, or had higher treatment motivation. In conclusion, findings provided initial evidence that subgroups may respond differently to a dog training program, however, more experimental research with larger sample sizes is needed.

Structural abnormalities in adolescents with conduct disorder and high versus low callous unemotional traits.

There may be distinct conduct disorder (CD) etiologies and neural morphologies in adolescents with high callous unemotional (CU) traits versus low CU traits. Here, we employed surface-based morphometry methods to investigate morphological differences in adolescents diagnosed with CD [42 with high CU traits (CD-HCU) and 40 with low CU traits (CD-LCU)] and healthy controls (HCs, N = 115) in China. Whole-brain analyses revealed significantly increased cortical surface area (SA) in the left inferior temporal cortex and the right precuneus, but decreased SA in the left superior temporal cortex in the CD-LCU group, compared with the HC group. There were no significant cortical SA differences between the CD-HCU and the HC groups. Compared to the CD-HCU group, the CD-LCU group had a greater cortical thickness (CT) in the left rostral middle frontal cortex. Region-of-interest analyses revealed significant group differences in the right hippocampus, with CD-HCU group having lower righthippocampal volumes than HCs. We did not detect significant group differences in the amygdalar volume, however, the right amygdalar volume was found to be a significant moderator of the correlation between CU traits and the proactive aggression in CD patients. The present results suggested that the manifestations of CD differ between those with high CU traits versus low CU traits, and underscore the importance of sample characteristics in understanding the neural substrates of CD.

Resting Heart Rate Mediates the Relationship between Parenting Style and Callous-Unemotional Traits in Chinese Children.

Despite increasing knowledge of social and biological risk factors for callous-unemotional (CU) traits, relatively less is known about how these two sets of risk factors combine to affect these traits. The current longitudinal study investigated pathways from parenting style to CU traits via resting heart rate in a three-year project. Parents of 382 children completed the Parenting Styles and Dimensions Questionnaire at Time 1 (children Mean age = 9.06, SD = 0.94, range = 7-11years), with the heart rate data collected at Time 2 (M = 10.16, SD = 0.93, range = 8-13years) and CU traits assessed at Time 3 (M = 11.06, SD = 0.94, range = 9-13years). We found that parenting style and CU traits were associated with resting heart rate, and that structural equation modeling showed resting heart rate to partially mediate the effect of parenting style on CU traits. Specifically, higher levels of authoritarian parenting were associated with lower resting heart rate, which in turn was linked to higher level of CU traits. On the contrary, children in the context of authoritative parenting showed relatively higher resting heart rate, which was predictive of lower CU traits. Overall, findings have implications for understanding the etiology of CU traits in children and developing effective prevention programs for children with affective deficits.

Modulation of Amygdala Response by Cognitive Conflict in Adolescents with Conduct Problems and Varying Levels of CU Traits

Adolescents with conduct problems and low callous-unemotional traits are characterised by high levels of reactive aggression. Prior studies suggest that they can have exaggerated neural and behavioural responses to negative emotional stimuli, accompanied by compromised affect regulation and atypical engagement of prefrontal areas during cognitive control. This pattern may in part explain their symptoms. Clarifying how neurocognitive responses to negative emotional stimuli can be modulated in this group has potential translational relevance. We present fMRI data from a cognitive conflict task in which the requirement to visually scan emotional (vs. calm) faces was held constant across low and high levels of cognitive conflict. Participants were 17 adolescent males with conduct problems and low levels of callous-unemotional traits (CP/LCU); 17 adolescents with conduct problems and high levels of callous-unemotional traits (CP/HCU, who typically show blunted reactivity to fear), and 18 typically developing controls (age range 10–16). Control participants showed typical attenuation of amygdala response to fear relative to calm faces under high (relative to low) conflict, replicating previous findings in a healthy adult sample. In contrast, children with CP/LCU showed a reduced (left amygdala) or reversed (right amygdala) attenuation effect under high cognitive conflict conditions. Children with CP/HCU did not differ from controls. Findings suggest atypical modulation of amygdala response as a function of task demands, and raise the possibility that those with CP/LCU are unable to implement typical regulation of amygdala response when cognitive task demands are high.

Parenting behavior and growth of child conduct problems: Moderation by callous-unemotional traits.

Although positive parenting behavior is central to efficacious interventions for child conduct problems (CP), studies of youth CP have focused mostly on negative parenting behavior. That is, few studies have examined dimensions of positive parenting behavior (e.g., positive reinforcement, involvement) as independent predictors of CP and even fewer have investigated their potential moderation by callous-unemotional (CU) traits. A sample of 184 6-9 year-old children with and without attention-deficit/hyperactivity disorder (ADHD) was followed prospectively for two years. Controlling for baseline ADHD diagnostic status, initial CP, and negative parenting (i.e., corporal punishment), we examined CU traits, positive reinforcement and involvement, and their interactions as predictors of two-year change in CP. Positive reinforcement and CU traits independently predicted increased rule breaking behavior whereas parental involvement inversely predicted aggressive behavior. A significant positive reinforcement x CU traits interaction suggested that positive reinforcement predicted a decrease in aggressive behavior, but only in children with low CU traits; conversely, positively reinforcement marginally predicted increased aggressive behavior among children with high CU traits. No other significant parenting x CU traits interaction was observed. We consider these findings within a developmental psychopathology framework where interactive exchanges underlie the development of CP.

Divergent Amygdala Volume Asymmetries for Male and Female Youth With High Versus Low Callous-Unemotional Traits

Although callous-unemotional (CU) traits have been associated with amygdala hypoactivity, it is unclear whether such traits are associated with amygdala structure. This study examines the relationship between amygdala structure and CU traits and considers sex differences in hemisphere-related asymmetries in this relationship. In this brain imaging study of children ( n = 272), a significant sex × hemisphere × CU traits interaction was observed. Females with high CU traits and males with low CU exhibited a rightward exaggerated amygdala volume asymmetry, whereas females with low CU traits and males with high CU traits did not. Findings may reflect sex-related influences related to CU traits and amygdala volume and are broadly consistent with a neurodevelopment perspective on psychopathic-like traits in children.

Is Callous Always Cold? A Critical Review of the Literature on Emotion and the Development of Callous-Unemotional Traits in Children.

Low emotional responsiveness is considered a core feature of callous-unemotional (CU) traits in childhood and, in the context of antisocial behavior, a precursor of psychopathic traits in adulthood. However, recent findings suggest that CU traits are not always characterized by low emotional responsiveness and the evidence base requires review. This review asks a fundamental question- 'Is callous always cold?'-with a specific focus on emotional responsiveness and CU traits in children with conduct problems (CPs). PRISMA review protocols were followed to identify literature reporting on emotional responsiveness for children 3-18years with CPs and varying (high and low) CU traits. Results from eligible studies were contrasted by age (children 3-11years, adolescents 12-18years), emotional responsive measurement type (physiological, behavioral, self-report), emotion-eliciting stimuli type (interactive activities, static imagery, film) and socio-emotional context of the stimuli (other-orientated, self-orientated, neutral). This review highlights considerable variation in results across studies: reduced emotional responsiveness was not synonymous with participants demonstrating high CU traits. A more consistent picture of reduced emotional responsiveness in participants with high CU traits was found when studies used physiological measures, when stimuli were other-orientated in socio-emotional context, and in older, adolescent samples. In conclusion, this paper advocates for a more nuanced understanding of the relationship between high CU traits and the specific factors involved in emotional responsiveness, ultimately suggesting that callous is not always cold. Given that emotional responsiveness is central to theories of moral development, these findings may suggest innovative approaches to early intervention.

Sex-dependent associations between maternal prenatal cortisol and child callous-unemotional traits: Findings from the Wirral Child Health and Development Study

BackgroundElevated maternal glucocorticoids during pregnancy may impact on fetal development in a sex-dependent way, leading to increased amygdala activation and increased risk for internalising disorders in females. Based on evidence implicating reduced amygdala activation in callous-unemotional (CU) traits, we predicted that elevated maternal cortisol in pregnancy would be associated with lower CU traits and elevated anxious-depressed symptoms, only in girls. MethodsParticipants were 225 members of a stratified subsample within an epidemiological longitudinal cohort (WCHADS). Salivary cortisol was measured over two days at 32 weeks gestation (on waking, 30-min post-waking and during the evening) and the log of the area under the curve (LogAUC) was calculated as an index of diurnal cortisol. Mothers reported on child CU traits and anxious-depressed symptoms at 2.5, 3.5 and 5.0 years of age. ResultsAs predicted there was a sex of child by cortisol interaction (p < .001) whereby elevated maternal cortisol was associated with lower child CU traits, explaining 25% of the variance, in girls, but not in boys. This effect remained when controlling for relevant confounders and anxious-depressed symptoms. By contrast, elevated maternal cortisol did not predict higher anxious-depressed symptoms in girls. ConclusionsThe study adds to growing evidence for sex-dependent effects of elevated maternal cortisol during pregnancy on early child psychopathology, consistent with mediation by elevated amygdala activation. The conditions under which, in girls, this is associated with heightened responsiveness to others’ distress characteristic of low CU traits, or with increased affective symptoms, require further study.

Emotion versus cognition: differential pathways to theory of mind for children with high versus low callous-unemotional traits.

Theory of mind (ToM) serves as a foundation for developing social cognition. Developmental theory suggests that early emotion understanding supports the development of ToM, but few studies have tested this question within longitudinal designs. Additionally, children with callous-unemotional (CU) traits directly challenge this theory as they appear to develop intact ToM despite deficits in emotion understanding. Inhibitory control is proposed as one possible compensatory mechanism for ToM development in children with high CU traits. We examined emotion understanding and inhibitory control at age 3 as predictors of ToM at age 6 and tested whether these pathways were different in children with high versus low levels of CU traits. Multimethod data included observations of child emotion understanding and inhibitory control and parent reports of CU traits drawn from a prospective, longitudinal study (N=240, 48% female). Consistent with our hypothesis, emotion understanding at age 3 significantly predicted ToM at age 6 only for children with low CU traits. Although there was a significant interaction between inhibitory control and CU traits in relation to later ToM, the simple slopes were not significant. We find prospective longitudinal evidence that emotion understanding is a developmental precursor of ToM. However, this pathway was not evident in children with high CU traits. Future research is needed to further explore potential mechanisms by which children with CU traits develop ToM with a potential focus on higher-order cognitive skills.

Parenting Is an Environmental Predictor of Callous-Unemotional Traits and Aggression: A Monozygotic Twin Differences Study

Callous-unemotional (CU) traits increase risk for children to develop severe childhood aggression and conduct disorder. CU traits are typically described as highly heritable, and debate continues about whether the parenting environment matters in their etiology. Strong genetically informed designs are needed to test for the presence of environmental links between parenting practices and CU traits. Our objective was to determine whether parental harshness and parental warmth were related to children's aggression or CU traits when accounting for genetically mediated effects. We examined 227 monozygotic twin pairs (454 children) drawn from population-based and at-risk samples of twin families, leading to oversampling of twins living in poverty. We computed multi-informant difference scores combining mother and father reports of their harshness and warmth toward each twin, and differences in mother reports of each twin's aggression and CU traits. Twin differences in parental harshness were related to differences in both aggression and CU traits, such that the twin who received harsher parenting had higher aggression and more CU traits. Differences in parental warmth were uniquely related to differences in CU traits, such that the twin receiving warmer parenting evidenced lower CU traits. These effects were not moderated by child sex, age, or family income, with the exception that the relationship between differential parental harshness and differential child aggression was stronger among low-income families. Parenting is related to child CU traits and aggression, over and above genetically mediated effects, with low parental warmth being a unique environmental correlate of CU traits.