Anatomy of the dorsal default-mode network in conduct disorder: Association with callous-unemotional traits

Intranasal oxytocin modulates brain activity during emotional processing in children with treatment resistant conduct problems

One of the most highly replicated neural correlates of Conduct Problems (CP) is amygdala hypoactivity to another person's fear. We recently reported that this correlate was only observed in boys with persistent CP (i.e. antisocial behaviour that persisted following a gold-standard psychological intervention), suggesting that amygdala hypoactivity to fear could be an important neural signature for treatment-resistant CP, and a putative target for future treatments. Potential treatment candidates include the oxytocin system, as this has been reported to modulate amygdala activity and social behaviour across species. Further, in adults with antisocial personality disorder, intranasal oxytocin improved facial emotion recognition for fearful and happy faces. However, to-date, no-one has studied whether intranasal oxytocin can normalise neural processing differences in children with CP. Twenty boys (mean age 9.85±1.26 years) with persistent CP underwent functional magnetic resonance imaging in a within-subject randomised control design to investigate whether, compared to placebo, a single-dose of intranasal oxytocin could 'shift' abnormal neural processing to fear. Oxytocin failed to reduce amygdala hypoactivity to fearful faces, but increased activation in the posterior cingulate cortex / precuneus to happy faces. These findings tentatively suggest that intranasal oxytocin may promote a more neurotypical profile in treatment-resistant CP children, therefore, supporting the merit of investigating oxytocin in further larger clinical studies in this population.

Neuroticism and openness exhibit an anti-correlation pattern to dissociable default mode network: using resting connectivity and structural equation modeling analysis

The default mode network (DMN) can be subdivided into ventral and dorsal subsystems, which serve affective cognition and mental sense construction, respectively. An internally dissociated pattern of anti-correlations was observed between these two subsystems. Although numerous studies on neuroticism and openness have demonstrated the neurological functions of the DMN, little is known about whether different subsystems and hubs regions within the network are engaged in different functions in response to the two traits. We recruited 223 healthy volunteers in this study and collected their resting-state functional magnetic resonance imaging (fMRI) and NEO Five-Factor Inventory scores. We used independent component analysis (ICA) to obtain the DMN, before further decomposing it into the ventral and dorsal subsystems. Then, the network coherence of hubs regions within subsystems was extracted to construct two structural equation models (SEM) to explore the relationship between neuroticism and openness traits and DMN. We observed that the ventral DMN could significantly predict positive openness and negative neuroticism. The dorsal DMN was diametrically opposed. Additionally, the medial prefrontal cortex (mPFC) and middle temporal gyrus (MTG), both of which are core hubs of the subnetworks within the DMN, are significantly positively correlated with neuroticism and openness. These findings may point to a biological basis that neuroticism and openness are engaged in opposite mechanisms and support the hypothesis about the functional dissociation of the DMN.

Rapid white matter changes in children with conduct problems during a parenting intervention

Studies report that the microstructural integrity of the uncinate fasciculus (UF; connecting the anterior temporal lobe to the orbitofrontal cortex) is abnormal in adults with psychopathy and children with conduct problems (CP), especially those with high callous-unemotional (CU) traits. However, it is unknown if these abnormalities are 'fixed' or 'reversible'. Therefore, we tested the hypothesis that a reduction in CP symptoms, following a parenting intervention, would be associated with altered microstructural integrity in the UF. Using diffusion tensor imaging tractography we studied microstructural differences (mean diffusivity (MD) and radial diffusivity (RD)) in the UF of 43 typically developing (TD) and 67 boys with CP before and after a 14-week parenting intervention. We also assessed whether clinical response in CP symptoms or CU traits explained changes in microstructure following the intervention. Prior to intervention, measures of MD and RD in the UF were increased in CP compared to TD boys. Following intervention, we found that the CP group had a significant reduction in RD and MD. Further, these microstructural changes were driven by the group of children whose CU traits improved (but not CP symptoms as hypothesized). No significant microstructural changes were observed in the TD group. Our findings suggest, for the first time, that microstructural abnormalities in the brains of children with CP may be reversible following parenting intervention.

Antisocial behavior is associated with reduced frontoparietal network efficiency in youth

Youth antisocial behavior (AB) is associated with deficits in socioemotional processing, reward and threat processing and executive functioning. These deficits are thought to emerge from differences in neural structure, functioning and connectivity, particularly within the default, salience and frontoparietal networks. However, the relationship between AB and the organization of these networks remains unclear. To address this gap, the current study applied unweighted, undirected graph analyses to resting-state functional magnetic resonance imaging data in a cohort of 161 adolescents (95 female) enriched for exposure to poverty, a risk factor for AB. As prior work indicates that callous-unemotional (CU) traits may moderate the neurocognitive profile of youth AB, we examined CU traits as a moderator. Using multi-informant latent factors, AB was found to be associated with less efficient frontoparietal network topology, a network associated with executive functioning. However, this effect was limited to youth at low or mean levels of CU traits, indicating that these neural differences were specific to those high on AB but not CU traits. Neither AB, CU traits nor their interaction was significantly related to default or salience network topologies. Results suggest that AB, specifically, may be linked with shifts in the architecture of the frontoparietal network.

Centrality and interhemispheric coordination are related to different clinical/behavioral factors in attention deficit/hyperactivity disorder: a resting-state fMRI study

Eigenvector-Centrality (EC) has shown promising results in the field of Psychiatry, with early results also pertaining to ADHD. Parallel efforts have focused on the description of aberrant interhemispheric coordination in ADHD, as measured by Voxel-Mirrored-Homotopic-Connectivity (VMHC), with early evidence of altered Resting-State fMRI. A sample was collected from the ADHD200-NYU initiative: 86 neurotypicals and 89 participants with ADHD between 7 and 18 years old were included after quality control for motion. After preprocessing, voxel-wise EC and VMHC values between diagnostic groups were compared, and network-level values from 15 functional networks extracted. Age, ADHD severity (Connor's Parent Rating-Scale), IQ (Wechsler-Abbreviated-Scale), and right-hand dominance were correlated with EC/VMHC values in the whole sample and within groups, both at the voxel-wise and network-level. Motion was controlled by censoring time-points with Framewise-Displacement > 0.5 mm, as well as controlling for group differences in mean Framewise-Displacement values. EC was significantly higher in ADHD compared to neurotypicals in the left inferior Frontal lobe, Lingual gyri, Peri-Calcarine cortex, superior and middle Occipital lobes, right inferior Occipital lobe, right middle Temporal gyrus, Fusiform gyri, bilateral Cuneus, right Precuneus, and Cerebellum (FDR-corrected-p = 0.05). No differences were observed between groups in voxel-wise VMHC. EC was positively correlated with ADHD severity scores at the network level (at p-value < 0.01, Inattentive: Cerebellum rho = 0.273; Hyper/Impulsive: High-Visual Network rho = 0.242, Cerebellum rho = 0.273; Global Index Severity: High-Visual Network rho = 0.241, Cerebellum rho = 0.293). No differences were observed between groups for motion (p = 0.443). While EC was more related to ADHD psychopathology, VMHC was consistently and negatively correlated with age across all networks.

Psychopathy

Psychopathy is a personality disorder characterized by a constellation of affective, interpersonal, lifestyle and antisocial features whose antecedents can be identified in a subgroup of young people showing severe antisocial behaviour. The prevalence of psychopathy in the general population is thought to be ~1%, but is up to 25% in prisoners. The aetiology of psychopathy is complex, with contributions of both genetic and environmental risk factors, and gene-environment interactions and correlations. Psychopathy is characterized by structural and functional brain abnormalities in cortical (such as the prefrontal and insular cortices) and subcortical (for example, the amygdala and striatum) regions leading to neurocognitive disruption in emotional responsiveness, reinforcement-based decision-making and attention. Although no effective treatment exists for adults with psychopathy, preliminary intervention studies targeting key neurocognitive disturbances have shown promising results. Given that psychopathy is often comorbid with other psychiatric disorders and increases the risk of physical health problems, educational and employment failure, accidents and criminality, the identification of children and young people at risk for this personality disorder and preventative work are important. Indeed, interventions that target the antecedents of psychopathic features in children and adolescents have been found to be effective.

Is the Psychopathic Brain an Artifact of Coding Bias? A Systematic Review

Questionable research practices are a well-recognized problem in psychology. Coding bias, or the tendency of review studies to disproportionately cite positive findings from original research, has received comparatively little attention. Coding bias is more likely to occur when original research, such as neuroimaging, includes large numbers of effects, and is most concerning in applied contexts. We evaluated coding bias in reviews of structural magnetic resonance imaging (sMRI) studies of PCL-R psychopathy. We used PRISMA guidelines to locate all relevant original sMRI studies and reviews. The proportion of null-findings cited in reviews was significantly lower than those reported in original research, indicating coding bias. Coding bias was not affected by publication date or review design. Reviews recommending forensic applications—such as treatment amenability or reduced criminal responsibility—were no more accurate than purely theoretical reviews. Coding bias may have contributed to a perception that structural brain abnormalities in psychopaths are more consistent than they actually are, and by extension that sMRI findings are suitable for forensic application. We discuss possible sources for the pervasive coding bias we observed, and we provide recommendations to counteract this bias in review studies. Until coding bias is addressed, we argue that this literature should not inform conclusions about psychopaths' neurobiology, especially in forensic contexts.

Neural processing of socioemotional content in conduct-disordered juvenile offenders with limited prosocial emotions

BACKGROUND

Reflecting evidence on Callous-Unemotional (CU) traits (e.g., lack of empathy and guilt, shallow affect), the DSM-5 added a categorical CU-based specifier for Conduct Disorder (CD), labeled 'with Limited Prosocial Emotions' (LPE). Theory and prior work suggest that CD youths with and without LPE will likely differ in neural processing of negative socioemotional content. This proposition, however, is mainly derived from studies employing related, yet distinct, operationalizations of CU traits (e.g., dimensional measure/median split/top quartile), thus precluding direct examination of LPE-specific neurocognitive deficits.

METHODS

Employing a DSM-5 informed LPE proxy, neural processing of recognizing and resonating negative socioemotional content (angry and fearful faces) was therefore examined here among CD offenders with LPE (CD/LPE+; N = 19), relative to CD offenders without LPE (CD/LPE-; N = 31) and healthy controls (HC; N = 31).

RESULTS

Relative to HC and CD/LPE- youths and according to a linearly increasing trend (CD/LPE- < HC < CD/LPE+), CD/LPE+ youths exhibited hyperactivity within dorsolateral, dorsomedial, and ventromedial prefrontal regions during both emotion recognition and resonance. During emotion resonance, CD/LPE+ youths additionally showed increased activity within the posterior cingulate and precuneal cortices in comparison to HC and CD/LPE- youths, which again followed a linearly increasing trend (CD/LPE- < HC < CD/LPE+). These effects moreover seemed specific to the LPE specifier, when compared to a commonly employed method for CU-based grouping in CD (i.e., median split on CU scores).

CONCLUSIONS

These data cautiously suggest that CD/LPE+ youths may exhibit an over-reliance on cortical neurocognitive systems when explicitly processing negative socioemotional information, which could have adverse downstream effects on relevant socioemotional functions. The findings thus seem to provide novel, yet preliminary, clues on the neurocognitive profile of CD/LPE+, and additionally highlight the potential scientific utility of the LPE specifier.

l-Cystine is associated with the dysconnectivity of the default-mode network and salience network in attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disorder. Distributed dysconnectivity within both the default-mode network (DMN) and the salience network (SN) has been observed in ADHD. L-cystine may serve as a neuroprotective molecule and signaling pathway, as well as a biomarker of ADHD. The purpose of this study was to explore whether differential brain network connectivity is associated with peripheral L-cystine levels in ADHD patients. We recruited a total of 31 drug-naïve patients with ADHD (mean age: 10.4 years) and 29 healthy controls (mean age: 10.3 years) that underwent resting state functional magnetic resonance imaging scans. Functional connectomes were generated for each subject, and we examined the cross-sectional group difference in functional connectivity (FC) within and between DMN and SN. L-cystine plasma levels were determined using high-performance chemical isotope labeling (CIL)-based liquid chromatography-mass spectrometry (LC-MS). Compared to the control group, the ADHD group showed decreased FC of dorsal DMN (p = 0.031), as well as decreased FC of precuneus-post SN (p = 0.006) and ventral DMN-post SN (p = 0.001). The plasma L-cystine levels of the ADHD group were significantly higher than in the control group (p = 0.002). Furthermore, L-cystine levels were negatively correlated with FC of precuneus-post SN (r = -0.404, p = 0.045) and ventral DMN-post SN (r = -0.540, p = 0.007). The findings suggest that decreased synergies of DMN and SN may serve as neurobiomarkers for ADHD, while L-cystine may be involved in the pathophysiology of network dysconnectivity. Future studies on the molecular mechanism of the cystine-glutamate system in brain network connectivity are warranted.

The associations of comorbid substance use disorders and psychiatric conditions with adolescent brain structure and function: A review

Adolescence is a period of rapid neural and behavioral development that often precipitates substance use, substance use disorders (SUDs), and other psychopathology. While externalizing disorders have been closely linked to SUD epidemiologically, the comorbidity of internalizing disorders and SUD is less well understood. Neuroimaging studies can be used to measure structural and functional developments in the brain that mediate the relationship between psychopathology and SUD in adolescence. Externalizing disorders and SUD are both associated with structural and functional changes in the basal ganglia and prefrontal cortex in adolescence. The neural mechanisms underlying internalizing disorders and SUD are less clear, but evidence points to involvement of the amygdala and prefrontal cortex. We also highlight independent contributions of SUD, which may vary in certain ways by the substances assessed. A deeper understanding of the neural basis of the relationship between psychopathology and SUD will allow for more informed interventions in this critical developmental stage.

A Macro-Structural Dispersion Characteristic of Brain White Matter and Its Application to Bipolar Disorder

OBJECTIVE

Our goal is to find distinct characteristics of brain white matter in bipolar disorder, of which the development of diagnostic imaging measures is necessary for early diagnosis and prospective studies.

METHODS

Given a tractogram dataset which is a dense set of white matter fiber pathways of the whole brain obtained from diffusion magnetic resonance imaging, we propose to compute a global measure for a voxel from the dispersion statistics of a set of fibers which indicates the complexity of the white matter voxel not locally but at macroscopic scales.

RESULTS

Our findings demonstrate that macro-structural dispersion information is significant for discrimination of the bipolar patients from the healthy controls, particularly in the frontally associative bundles such as cingulum and inferior occipito-frontal fascicles.

CONCLUSION

The proposed measure is as informative as the local diffusion measures for the detection of changes in the white matter regions.

SIGNIFICANCE

Our findings show that the proposed measure is a potential diagnostic imaging marker in bipolar disorder and the proposed novel dispersion map of the brain could be used for other neurological applications.

Sex differences in associations of socioemotional dispositions measured in childhood and adolescence with brain white matter microstructure 12 years later

Predictive associations were estimated between socioemotional dispositions measured at 10-17 years using the Child and Adolescent Dispositions Scale (CADS) and future individual differences in white matter microstructure measured at 22-31 years of age. Participants were 410 twins (48.3% monozygotic) selected for later neuroimaging by oversampling on risk for psychopathology from a representative sample of child and adolescent twins. Controlling for demographic covariates and total intracranial volume (TICV), each CADS disposition (negative emotionality, prosociality, and daring) rated by one of the informants (parent or youth) significantly predicted global fractional anisotropy (FA) averaged across the major white matter tracts in brain in adulthood, but did so through significant interactions with sex after false discovery rate (FDR) correction. In females, each 1 SD difference in greater parent-rated prosociality was associated with 0.43 SD greater FA (p < 0.0008). In males, each 1 SD difference in greater parent-rated daring was associated with 0.24 SD lower FA (p < 0.0008), and each 1 SD difference in greater youth-rated negative emotionality was associated with 0.18 SD greater average FA (p < 0.0040). These findings suggest that CADS dispositions are associated with FA, but associations differ by sex. Exploratory analyses suggest that FA may mediate the associations between dispositions and psychopathology in some cases. These associations over 12 years could reflect enduring brain-behavior associations in spite of transactions with the environment, but could equally reflect processes in which dispositional differences in behavior influence the development of white matter. Future longitudinal studies are needed to resolve the causal nature of these sex-moderated associations.

The DSM-5 with Limited Prosocial Emotions Specifier for Conduct Disorder: a Systematic Literature Review

DSM-5 added a categorically defined specifier (‘with Limited Prosocial Emotions’; LPE) for the diagnosis of conduct disorder (CD). This paper systematically reviews the evidence base for this specifier in children and adolescents who are diagnosed with CD. Computer-assisted searches were executed and identified 181 potentially relevant papers. Eventually, nine papers were included in this review, referring to eight unique samples. All studies constructed an LPE measure by pulling the same items from the same rating scales that were used in the development of the DSM-5 LPE specifier. The prevalence of youth with CD who met criteria for this novel LPE specifier (CD + LPE) ranged from 6.1% to 83.7%. The studies greatly varied in the features used to test the viability of the DSM-5 LPE specifier. The most commonly used features relate to severity of antisocial behavior, low neuroticism (or lack of anxiety and depression), and treatment responsiveness. Available work altogether showed that CD + LPE youth displayed higher levels of past antisocial behaviour than CD Only youth, but failed to reveal other group differences that corroborate with expectations. Effect sizes typically were in the small to moderate range, suggesting that the practical usefulness of the group differences is limited. Empirical work shows that this specifier should not be used for clinical decision-making when relying on items from measures that have been used in the development of the LPE specifier. Crucially, limitations that hallmark the few studies on the topic hamper any firm conclusion about the usefulness of the specifier.

White matter microstructure of the extended limbic system in male and female youth with conduct disorder

BACKGROUND

Previous studies of conduct disorder (CD) have reported structural and functional alterations in the limbic system. However, the white matter tracts that connect limbic regions have not been comprehensively studied. The uncinate fasciculus (UF), a tract connecting limbic to prefrontal regions, has been implicated in CD. However, CD-related alterations in other limbic tracts, such as the cingulum and the fornix, have not been investigated. Furthermore, few studies have examined the influence of sex and none have been adequately powered to test whether the relationship between CD and structural connectivity differs by sex. We examined whether adolescent males and females with CD exhibit differences in structural connectivity compared with typically developing controls.

METHODS

We acquired diffusion-weighted magnetic resonance imaging data from 101 adolescents with CD (52 females) and 99 controls (50 females). Data were processed for deterministic spherical deconvolution tractography. Virtual dissections of the UF, the three subdivisions of the cingulum [retrosplenial cingulum (RSC), parahippocampal and subgenual cingulum], and the fornix were performed and measures of fractional anisotropy (FA) and hindrance-modulated orientational anisotropy (HMOA) were analysed.

RESULTS

The CD group had lower FA and HMOA in the right RSC tract relative to controls. Importantly, these effects were moderated by sex - males with CD significantly lower FA compared to male controls, whereas CD and control females did not differ.

CONCLUSIONS

Our results highlight the importance of considering sex when studying the neurobiological basis of CD. Sex differences in RSC connectivity may contribute to sex differences in the clinical presentation of CD.

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.

Neural Correlates of Empathy in Boys With Early Onset Conduct Disorder

Background: A deficit in empathy has repeatedly been described in individuals with conduct disorder (CD), and in particular in those with callous unemotional traits. Until now, little is known about the neural basis of empathy in children and adolescents with early onset conduct disorder. The aim of this study was to examine neural responses during empathizing in children and adolescents with CD with a task that allowed to differentiate between the judgment of the emotional states of other people and the own emotional response to other people's emotional state. Moreover, we investigated associations of callous-unemotional traits and neural activations during empathizing. Methods: Using functional magnetic resonance imaging (fMRI) we investigated 14 boys with early onset CD and 15 typically developing (TDC) age matched controls between 8 and 16 years of age. Happy and sad faces were presented, and participants were asked to either infer the emotional state from the face (other-task) or to judge their own emotional response (self-task). A perceptual decision on faces was used as a control task. Individual empathic abilities and callous unemotional traits were assessed. Results: During the other task, TDC boys showed significantly larger right amygdala responses than CD boys. Higher empathic abilities (as assessed with the Bryant Index of Empathy) were associated with higher responses in the right amygdala within the CD boys and across the entire sample. Moreover, across the entire sample, callous-unemotional traits were negatively related to the BOLD-response in the right amygdala. CD boys showed larger responses in the dorsal and ventral medial prefrontal cortex across tasks and increased activation in dorsal medial prefrontal cortex specifically during the self-conditions, which were also related to empathic abilities within the CD boys. Conclusions: The data emphasize the important role of the amygdala in empathy related emotional processing. Diminished amygdala responses and their association with low empathy suggest a pivotal influence of impaired amygdala processing in early-onset CD, in particular for deficits in empathic behavior and related callous-unemotional-traits. Elevated response in the medial prefrontal cortex in boys with CD point toward increased involvement of brain areas related to self-referential processing and cognitive empathy during empathizing.

White Matter Microstructure in Youths With Conduct Disorder: Effects of Sex and Variation in Callous Traits

OBJECTIVE

Studies using diffusion tensor imaging (DTI) to investigate white matter (WM) microstructure in youths with conduct disorder (CD) have reported disparate findings. We investigated WM alterations in a large sample of youths with CD, and examined the influence of sex and callous-unemotional (CU) traits.

METHOD

DTI data were acquired from 124 youths with CD (59 female) and 174 typically developing (TD) youths (103 female) 9 to 18 years of age. Tract-based spatial statistics tested for effects of diagnosis and sex-by-diagnosis interactions. Associations with CD symptoms, CU traits, a task measuring impulsivity, and the impact of comorbidity, and age- and puberty-related effects were examined.

RESULTS

Youths with CD exhibited higher axial diffusivity in the corpus callosum and lower radial diffusivity and mean diffusivity in the anterior thalamic radiation relative to TD youths. Female and male youths with CD exhibited opposite changes in the left hemisphere within the internal capsule, fornix, posterior thalamic radiation, and uncinate fasciculus. Within the CD group, CD symptoms and callous traits exerted opposing influences on corpus callosum axial diffusivity, with callous traits identified as the unique clinical feature predicting higher axial diffusivity and lower radial diffusivity within the corpus callosum and anterior thalamic radiation, respectively. In an exploratory analysis, corpus callosum axial diffusivity partially mediated the association between callous traits and impulsive responses to emotional faces. Results were not influenced by symptoms of comorbid disorders, and no age- or puberty-related interactions were observed.

CONCLUSION

WM alterations within the corpus callosum represent a reliable neuroimaging marker of CD. Sex and callous traits are important factors to consider when examining WM in CD.

Default Mode Network structural alterations in Kocher-Monro trajectory white matter transection: A 3 and 7 tesla simulation modeling approach

The Kocher-Monro trajectory to the cerebral ventricular system represents one of the most common surgical procedures in the field of neurosurgery. Several studies have analyzed the specific white matter disruption produced during this intervention, which has no reported adverse neurological outcomes. In this study, a graph-theoretical approach was applied to quantify the structural alterations in whole-brain level connectivity. To this end, 132 subjects were randomly selected from the Human Connectome Project dataset and used to create 3 independent 44 subjects groups. Two of the groups underwent a simulated left/right Kocher-Monro trajectory and the third was kept as a control group. For the right Kocher-Monro approach, the nodal analysis revealed decreased strength in the anterior cingulate gyrus of the transected hemisphere. The network-based statistic analysis revealed a set of right lateralized subnetworks with decreased connectivity strength that is consistent with a subset of the Default Mode Network, Salience Network, and Cingulo-Opercular Network. These findings could allow for a better understanding of structural alterations caused by Kocher-Monro approaches that could reveal previously undetected clinical alterations and inform the process of designing safer and less invasive cerebral ventricular approaches.

Distinct associations between fronto-striatal glutamate concentrations and callous-unemotional traits and proactive aggression in disruptive behavior

Disruptive behavior is associated with societally and personally problematic levels of aggression and has been linked to abnormal structure and function of fronto-amygdala-striatal regions. Abnormal glutamatergic signalling within this network may play a role in aggression. However, disruptive behavior does not represent a homogeneous construct, but can be fractionated across several dimensions. Of particular interest, callous-unemotional (CU) traits have been shown to modulate the severity, neural and behavioural characterisation, and therapeutic outcomes of disruptive behaviour disorders (DBDs) and aggression. Further, individuals showing disruptive behavior differ to the extent that they engage in subtypes of aggression (i.e., proactive [PA] and reactive aggression [RA]) which may also represent distinct therapeutic targets. Here we investigated how glutamate signalling within the fronto-amygdala-striatal circuitry was altered along these dimensions in youths showing disruptive behavior (n = 140) and typically developing controls (TD, n = 93) within the age-range of 8-18 years. We used proton magnetic resonance spectroscopy (¹H-MRS) in the anterior cingulate cortex (ACC), striatum, amygdala and insula and associated glutamate concentrations with continuous measures of aggression and CU-traits using linear mixed-effects models. We found evidence of a dissociation for the different measures and glutamate concentrations. CU traits were associated with increased ACC glutamate ('callousness': b = .19, t (108) = 2.63, p = .01, r = .25; 'uncaring': b = .18, t (108) = 2.59, p = .011, r = .24) while PA was associated with decreased striatal glutamate concentration (b = -.23, t (28) = -3.02, p = .005, r = .50). These findings suggest dissociable correlates of CU traits and PA in DBDs, and indicate that the ACC and striatal glutamate may represent novel pharmacological targets in treating these different aspects.

Flux of life

Developmental cognitive neuroscience is flourishing but there are new challenges and new questions to be asked. I argue that we need a bigger picture and an evolutionary framework. This brings some challenges, such as the need to rewrite the old story of nature and nurture, and the need to systematically investigate innate predispositions. While brain imaging has provided some splendid insights and new puzzles to solve, its limitations must not be ignored. Can they help us to find out more about the extent to which the infant brain already configures the adult brain? Can we find out why neurodevelopmental disorders often have severe consequences on cognition and behaviour, despite the mitigating force of brain plasticity? I wish to encourage researchers of the future to take risks by letting their imagination inspire theories to pursue hard questions. I end with a wish list of topics, from start-up kits to abstract reasoning, that I hope can be tackled afresh. However, collecting physiological and behavioural data is not enough. We need a deeper understanding of the mechanisms of cognitive development.

Conduct disorder

Conduct disorder (CD) is a common and highly impairing psychiatric disorder that usually emerges in childhood or adolescence and is characterized by severe antisocial and aggressive behaviour. It frequently co-occurs with attention-deficit/hyperactivity disorder (ADHD) and often leads to antisocial personality disorder in adulthood. CD affects ~3% of school-aged children and is twice as prevalent in males than in females. This disorder can be subtyped according to age at onset (childhood-onset versus adolescent-onset) and the presence or absence of callous-unemotional traits (deficits in empathy and guilt). The aetiology of CD is complex, with contributions of both genetic and environmental risk factors and different forms of interplay among the two (gene-environment interaction and correlation). In addition, CD is associated with neurocognitive impairments; smaller grey matter volume in limbic regions such as the amygdala, insula and orbitofrontal cortex, and functional abnormalities in overlapping brain circuits responsible for emotion processing, emotion regulation and reinforcement-based decision-making have been reported. Lower hypothalamic-pituitary-adrenal axis and autonomic reactivity to stress has also been reported. Management of CD primarily involves parent-based or family-based psychosocial interventions, although stimulants and atypical antipsychotics are sometimes used, especially in individuals with comorbid ADHD.

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

BACKGROUND

Callous traits during childhood, e.g., lack of remorse and shallow affect, are a key risk marker for antisocial behavior. Although callous traits have been found to be associated with structural and functional brain alterations, evidence to date has been almost exclusively limited to small, high-risk samples of boys. We characterized gray and white matter brain correlates of callous traits in over 2000 children from the general population.

METHODS

Data on mother-reported callous traits and brain imaging were collected at age 10 years from participants of the Generation R Study. Structural magnetic resonance imaging was used to investigate brain morphology using volumetric indices and whole-brain analyses (n = 2146); diffusion tensor imaging was used to assess global and specific white matter microstructure (n = 2059).

RESULTS

Callous traits were associated with lower global brain (e.g., total brain) volumes as well as decreased cortical surface area in frontal and temporal regions. Global mean diffusivity was negatively associated with callous traits, suggesting higher white matter microstructural integrity in children with elevated callous traits. Multiple individual tracts, including the uncinate and cingulum, contributed to this global association. Whereas no gender differences were observed for global volumetric indices, white matter associations were present only in girls.

CONCLUSIONS

This is the first study to provide a systematic characterization of the structural neural profile of callous traits in the general pediatric population. These findings extend previous work based on selected samples by demonstrating that childhood callous traits in the general population are characterized by widespread macrostructural and microstructural differences across the brain.

Structural Brain Connectivity in Childhood Disruptive Behavior Problems: A Multidimensional Approach

BACKGROUND

Studies of white matter connectivity in children with disruptive behavior have yielded inconsistent results, possibly owing to the trait's heterogeneity, which comprises diverse symptoms like physical aggression, irritability, and delinquency. This study examined associations of global and specific white matter connectivity with childhood disruptive behavior problems, while accounting for their complex multidimensionality.

METHODS

In a large cross-sectional population-based study of 10-year-old preadolescents (n = 2567), we assessed four previously described empirically derived dimensions of disruptive behavior problems using the Child Behavior Checklist: physical aggression, irritability, disobedient behavior, and delinquent behavior. Global and specific white matter microstructure was assessed by diffusion tensor imaging.

RESULTS

Global fractional anisotropy and mean diffusivity were not associated with broad measures of disruptive behavior, e.g., Child Behavior Checklist externalizing problems scale. Global fractional anisotropy was negatively associated with delinquent behavior (β = -.123, p_{false discovery rate adjusted} = .028) and global mean diffusivity was positively associated with delinquent behavior (β = .205, p_{false discovery rate adjusted} < 0.001), suggesting reduced white matter microstructure in preadolescents with higher levels of delinquent behavior. Lower white matter microstructure in the inferior longitudinal fasciculus, superior longitudinal fasciculus, cingulum, and uncinate underlie these associations. Global white matter microstructure was not associated with physical aggression, irritability, or disobedient behavior.

CONCLUSIONS

Delinquent behavior, a severe manifestation of childhood disruptive behavior, was associated with lower white matter microstructure in tracts connecting frontal and temporal lobes. These brain regions are involved in decision making, reward processing, and emotion regulation. This study demonstrated that incorporating the multidimensional nature of childhood disruptive behavior traits shows promise in advancing the search for elucidating neurobiological correlates of disruptive behavior.