Neural Profile of Callous Traits in Children: A Population-Based Neuroimaging Study

Child Neuropsychological Functioning and Interpersonal Callousness as Predictors of Externalising Behaviour in Early Adolescence: A Prospective Population-based Study

Externalizing problems are a key predictor of individual functioning in adulthood. Therefore, identifying possible risk factors for externalising problems is valuable for optimising prevention and treatment programmes. Previous research has shown that (domains of) neuropsychological functioning predict externalising problems later in life. However, the influence of callous traits, and sex as potential moderators in this relation remains unclear. The aim of this study was to examine associations between neuropsychological functioning in children (at age 8 years) and later externalising behaviour in adolescence (at age 14 years), as well as to test the role of callous traits (at age 10 years) and sex as moderating factors. The analyses were conducted using data from 661 Dutch children from the population-based Generation R Study (47.2% female). We found no association between neuropsychological functioning and later externalising behaviour. However, callous traits predicted externalising problems at age 14 years. Further, callous traits moderated the association between neuropsychological functioning and externalising behaviour, though this association dropped below the statistical significance level when adjusted for confounders. Specifically, while higher neuropsychological functioning was associated with more externalising behaviour in children with high callous traits, lower neuropsychological functioning was not associated with externalising behaviour in children with low callous traits. Although boys showed significantly higher externalising behaviours compared to girls, no moderating effect of sex was found on the association between neuropsychological functioning and externalising behaviour. These results add to a growing body of evidence supporting a distinct neurocognitive profile in children with high vs low callousness.

How reliable are amygdala findings in psychopathy? A systematic review of MRI studies

The amygdala is a key component in predominant neural circuitry models of psychopathy. Yet, after two decades of neuroimaging research on psychopathy, the reproducibility of amygdala findings is questionable. We systematically reviewed MRI studies (81 of adults, 53 of juveniles) to determine the consistency of amygdala findings across studies, as well as within specific types of experimental tasks, community versus forensic populations, and the lowest- versus highest-powered studies. Three primary findings emerged. First, the majority of studies found null relationships between psychopathy and amygdala structure and function, even in the context of theoretically relevant tasks. Second, findings of reduced amygdala activity were more common in studies with low compared to high statistical power. Third, the majority of peak coordinates of reduced amygdala activity did not fall primarily within the anatomical bounds of the amygdala. Collectively, these findings demonstrate significant gaps in the empirical support for the theorized role of the amygdala in psychopathy and indicate the need for novel research perspectives and approaches in this field.

Multivariate Genetic Structure of Externalizing Behavior and Structural Brain Development in a Longitudinal Adolescent Twin Sample

Externalizing behavior in its more extreme form is often considered a problem to the individual, their families, teachers, and society as a whole. Several brain structures have been linked to externalizing behavior and such associations may arise if the (co)development of externalizing behavior and brain structures share the same genetic and/or environmental factor(s). We assessed externalizing behavior with the Child Behavior Checklist and Youth Self Report, and the brain volumes and white matter integrity (fractional anisotropy [FA] and mean diffusivity [MD]) with magnetic resonance imaging in the BrainSCALE cohort, which consisted of twins and their older siblings from 112 families measured longitudinally at ages 10, 13, and 18 years for the twins. Genetic covariance modeling based on the classical twin design, extended to also include siblings of twins, showed that genes influence externalizing behavior and changes therein (h² up to 88%). More pronounced externalizing behavior was associated with higher FA (observed correlation r_ph up to +0.20) and lower MD (r_ph up to −0.20), with sizeable genetic correlations (FA r_a up to +0.42; MD r_a up to −0.33). The cortical gray matter (CGM; r_ph up to −0.20) and cerebral white matter (CWM; r_ph up to +0.20) volume were phenotypically but not genetically associated with externalizing behavior. These results suggest a potential mediating role for global brain structures in the display of externalizing behavior during adolescence that are both partially explained by the influence of the same genetic factor.

Parenting in the Context of the Child: Genetic and Social Processes

The focus on the role of parenting in child development has a long-standing history. When measures of parenting precede changes in child development, researchers typically infer a causal role of parenting practices and attitudes on child development. However, this research is usually conducted with parents raising their own biological offspring. Such research designs cannot account for the effects of genes that are common to parents and children, nor for genetically influenced traits in children that influence how they are parented and how parenting affects them. The aim of this monograph is to provide a clearer view of parenting by synthesizing findings from the Early Growth and Development Study (EGDS). EGDS is a longitudinal study of adopted children, their birth parents, and their rearing parents studied across infancy and childhood. Families (N = 561) were recruited in the United States through adoption agencies between 2000 and 2010. Data collection began when adoptees were 9 months old (males = 57.2%; White 54.5%, Black 13.2%, Hispanic/Latinx 13.4%, Multiracial 17.8%, other 1.1%). The median child age at adoption placement was 2 days (M = 5.58, SD = 11.32). Adoptive parents were predominantly in their 30s, White, and coming from upper-middle- or upper-class backgrounds with high educational attainment (a mode at 4-year college or graduate degree). Most adoptive parents were heterosexual couples, and were married at the beginning of the project. The birth parent sample was more racially and ethnically diverse, but the majority (70%) were White. At the beginning of the study, most birth mothers and fathers were in their 20s, with a mode of educational attainment at high school degree, and few of them were married. We have been following these family members over time, assessing their genetic influences, prenatal environment, rearing environment, and child development. Controlling for effects of genes common to parents and children, we confirmed some previously reported associations between parenting, parent psychopathology, and marital adjustment in relation to child problematic and prosocial behavior. We also observed effects of children's heritable characteristics, characteristics thought to be transmitted from parent to child by genetic means, on their parents and how those effects contributed to subsequent child development. For example, we found that genetically influenced child impulsivity and social withdrawal both elicited harsh parenting, whereas a genetically influenced sunny disposition elicited parental warmth. We found numerous instances of children's genetically influenced characteristics that enhanced positive parental influences on child development or that protected them from harsh parenting. Integrating our findings, we propose a new, genetically informed process model of parenting. We posit that parents implicitly or explicitly detect genetically influenced liabilities and assets in their children. We also suggest future research into factors such as marital adjustment, that favor parents responding with appropriate protection or enhancement. Our findings illustrate a productive use of genetic information in prevention research: helping parents respond effectively to a profile of child strengths and challenges rather than using genetic information simply to identify some children unresponsive to current preventive interventions.

Sex matters: association between callous-unemotional traits and uncinate fasciculus microstructure in youths with conduct disorder

Among youths with conduct disorder, those with callous-unemotional traits are at increased risk for persistent antisocial behaviour. Although callous-unemotional traits have been found to be associated with white-matter brain abnormalities, previous diffusion imaging studies were conducted in small samples, preventing examination of potential sex by callous-unemotional traits interaction effects on white matter. Here, we used tract-based spatial statistics at a whole-brain level and within regions of interest to compare the white matter correlates of callous-unemotional traits in female vs. male youths with conduct disorder, in a sample (n = 124) recruited through a multi-site protocol. A sex-specific association between callous-unemotional traits and white matter was found in the left uncinate fasciculus, where callous-unemotional traits were positively associated with axial diffusivity in males, while an opposite pattern was found in females. These findings are in line with previous studies suggesting that the uncinate fasciculus is a key tract implicated in the development of psychopathy, but also add to recent evidence showing that sexual dimorphism needs to be taken into account when examining the structural correlates of mental disorders in general, and callous-unemotional traits in conduct disorder in particular.

Air pollution exposure during pregnancy and childhood and brain morphology in preadolescents

BACKGROUND

Studies investigating the relationship between exposure to air pollution and brain development using magnetic resonance images are emerging. However, most studies have focused only on prenatal exposures, and have included a limited selection of pollutants. Here, we aim to expand the current knowledge by studying pregnancy and childhood exposure to a wide selection of pollutants, and brain morphology in preadolescents.

METHODS

We used data from 3133 preadolescents from a birth cohort from Rotterdam, the Netherlands (enrollment: 2002-2006). Concentrations of nitrogen oxides, coarse, fine, and ultrafine particles, and composition of fine particles were estimated for participant's home addresses in pregnancy and childhood, using land use regression models. Structural brain images were obtained at age 9-12 years. We assessed the relationships of air pollution exposure, with brain volumes, and surface-based morphometric data, adjusting for socioeconomic and life-style characteristics, using single as well as multi-pollutant approach.

RESULTS

No associations were observed between air pollution exposures and global volumes of total brain, and cortical and subcortical grey matter. However, we found associations between higher pregnancy and childhood air pollution exposures with smaller corpus callosum, smaller hippocampus, larger amygdala, smaller nucleus accumbens, and larger cerebellum (e.g. -69.2mm³ hippocampal volume [95%CI -129.1 to -9.3] per 1ng/m³ increase in pregnancy exposure to polycyclic aromatic hydrocarbons). Higher pregnancy exposure to air pollution was associated with smaller cortical thickness while higher childhood exposure was associated with predominantly larger cortical surface area.

CONCLUSION

Higher pregnancy or childhood exposure to several air pollutants was associated with altered volume of several brain structures, as well as with cortical thickness and surface area. Associations showed some similarity to delayed maturation and effects of early-life stress.

Callous-unemotional traits and reduced default mode network connectivity within a community sample of children

Callous-unemotional (CU) traits characterize a subset of youth at risk for persistent and serious antisocial behavior. Differences in resting state connectivity in the default mode network (DMN) have been associated with CU traits in forensic and clinical samples of adolescents and with deficient interpersonal/affective traits (often operationalized as Factor 1 psychopathy traits) in adults. It is unclear whether these brain-behavior associations extend to community-based children. Using mixed model analyses, we tested the associations between CU traits and within-network resting-state connectivity of seven task-activated networks and the DMN using data from 9,636 9-11-year-olds in the Adolescent Brain Cognitive Development (ABCD) study. Even after accounting for comorbid externalizing problems, higher levels of CU traits were associated with reduced connectivity within the DMN. This finding is consistent with prior literature surrounding psychopathy and CU traits in clinically and forensically based populations, suggesting the correlation likely exists on a spectrum, can be detected in childhood, and is not restricted to children with significant antisocial behavior.

Recent neuro-imaging findings with respect to conduct disorder, callous-unemotional traits and psychopathy

PURPOSE OF REVIEW

To review recent neuro-imaging findings with respect to conduct disorder and callous-unemotional traits in childhood and comparable psychopathy in adult-hood that deepen the literature in important ways.

RECENT FINDINGS

Recent structural findings particularly bring clarity to the literature. First, they reinforce previous work indicating that severity of psychopathy is positively associated with extent of cavum septum pellucidum. This suggests psychopathy is associated with early neurodevelopmental disruption within limbic structures. Second, they clarify the direction of the association between conduct disorder and particularly callous-unemotional traits and white matter tract abnormalities even if it remains less transparent exactly which tracts are disrupted. However, conclusions based on recent functional imaging studies are more equivocal with inconsistencies in direction of emotional (albeit with notably more work confirming the previous reports of hypo-responsiveness in limbic regions) and reward responsiveness.

SUMMARY

The recent data are, for the most part, consistent with a view that callous-unemotional traits/psychopathy represents an early appearing neuro-developmental disorder particularly associated with compromised emotional (limbic) functioning. However, some patients presenting with severe antisocial behavior may also show hyper-threat sensitivity, perhaps reflecting trauma exposure, and require different clinical interventions.

Sex differences in antisocial and aggressive disorders that onset in childhood and persist into adulthood

As many as 10.7% of males and 7.5% of females display early-onset, stable, antisocial and aggressive behavior (ESAAB). Most research has focused on males. These individuals are diagnosed with conduct disorder in childhood and antisocial personality disorder in adulthood, and a very few, almost all males, present the syndrome of psychopathy. ESAAB includes three subgroups: (1) conduct problems and callousness; (2) conduct problems, callousness, and anxiety; and (3) conduct problems. Heritability of the first two subtypes is high. This high heritability derives, at least in part, from genes involved in regulating serotonergic functioning early in life and to genotypes that confer sensitivity to trauma. The first subtype is rare and characterized by difficulty in face emotion recognition, especially fear and sadness, and hypoarousal as indexed by both autonomic and neural measures, and by structural brain abnormalities. By contrast, those with conduct problems, callousness, and anxiety are more common. They include a greater proportion of females and show hypersensitivity to threat that triggers reactive aggression and that is reflected in both autonomic and neural functioning. In sum, fewer females than males present ESAAB, but many characteristics, autonomic and neural correlates, and etiology are similar. Importantly, however, females with ESAAB play a critical role in the intergenerational transfer of antisocial behavior. Despite higher prevalence of EASSB in males than females, few sex differences in neural abnormalities have been identified.

Editorial: Conduct Disorder as a Neurodevelopmental Condition: White Matter Brain Microstructure and the Importance of Gender, Callous Traits, and Development

Although conduct disorder (CD) is a prevalent mental disorder in young people, relatively little research funding is allocated to investigating its etiology.¹ More funding for investigation is needed, as the presence of CD can greatly affect a young person's life across various domains, but can also impact their family, peers, and society at large. A better understanding of the neurodevelopment of CD can help tailoring treatment and prevention strategies. Furthermore, as we know that CD symptoms vary across affected individuals, the corresponding neural correlates might also be different for people with different symptom levels. Important factors to take into consideration here include gender; comorbidity, and distinct symptom patterns, such as the presence of callous-unemotional traits.