Phasic Versus Tonic Irritability and Associations with Family Accommodation Among Youth with Selective Mutism: A Latent Profile Analysis

Clinical presentations of selective mutism (SM) vary widely across affected youth. Although studies have explored general externalizing problems in youth with SM, research has not specifically examined patterns of irritability. Relatedly, research has not considered how affected families differentially accommodate the anxiety of youth with SM as a function of the child's temper outbursts (i.e., phasic irritability) and general angry mood (i.e., tonic irritability). Data were drawn from a sample of treatment-seeking children and adolescents with a primary diagnosis of selective mutism (N = 152; Mean age = 6.12 years; 67.11% female), and their caregivers. Latent profile analysis (LPA) was used to identify distinct profiles in SM youth that were characterized by varying levels of phasic and/or tonic irritability. Analyses further examined whether these different profiles were associated with different levels of family accommodation and global impairment. LPA identified 5 profiles: SM with No irritability, SM with Low Phasic Irritability, SM with High Phasic Irritability, SM with High Phasic and Moderate Tonic Irritability, and SM with High Phasic and High Tonic Irritability. Patterns of family accommodation and global impairment were highest among youth belonging to profiles characterized by high phasic irritability. Findings highlight separable patterns of irritability across youth with SM, with phasic irritability (i.e., temper outbursts) appearing particularly linked with increased family accommodation and overall global impairment. Assessing phasic irritability is critical for optimizing treatment in youth with SM and can be useful for flagging possible patterns of family accommodation contributing to overall impairment.

Associations Between Neighborhood Resources and Youth's Response to Reward Omission in a Task Modeling Negatively Biased Environments

OBJECTIVE

Neighborhoods provide essential resources (e.g., education, safe housing, green space) that influence neurodevelopment and mental health. However, we need a clearer understanding of the mechanisms mediating these relationships. Limited access to neighborhood resources may hinder youth from achieving their goals and, over time, shape their behavioral and neurobiological response to negatively biased environments blocking goals/ rewards.

METHOD

To test this hypothesis, 211 youth (∼ 13.0 years, 48% boys, 62% identifying as white, 75% with a psychiatric disorder diagnosis) performed a task during functional magnetic resonance imaging. Initially, rewards depended on performance (unbiased condition), but later, rewards were randomly withheld under the pretense that youth did not perform adequately (negatively biased condition), a manipulation that elicits frustration, sadness, and a broad response in neural networks. We investigated associations between the Childhood Opportunity Index (COI), which quantifies access to youth-relevant neighborhood features in one metric, and the multimodal response to the negatively biased condition, controlling for age, sex, medication, and psychopathology.

RESULTS

Youth from less-resourced neighborhoods responded with less anger (p<.001, marginal R2=.42) and more sadness (p<.001, marginal R2=.46) to the negatively biased condition than youth from well-resourced neighborhoods. On the neurobiological level, lower COI scores were associated with a more localized processing mode (p=.039, marginal R2=.076), reduced connectivity between the somato-motor-salience and the control network (p=.041, marginal R2=.040), and fewer provincial hubs in the somatic-motor-salience, control, and default mode networks (all pFWE<.05).

CONCLUSION

The present study adds to a growing literature documenting how inequity may affect the brain and emotions in youth. Future work should test whether findings generalize to more diverse samples and explore effects on neurodevelopmental trajectories and emerging mood disorders during adolescence.

Multivariate Assessment of Inhibitory Control in Youth: Links With Psychopathology and Brain Function

Inhibitory control is central to many theories of cognitive and brain development, and impairments in inhibitory control are posited to underlie developmental psychopathology. In this study, we tested the possibility of shared versus unique associations between inhibitory control and three common symptom dimensions in youth psychopathology: attention-deficit/hyperactivity disorder (ADHD), anxiety, and irritability. We quantified inhibitory control using four different experimental tasks to estimate a latent variable in 246 youth (8-18 years old) with varying symptom types and levels. Participants were recruited from the Washington, D.C., metro region. Results of structural equation modeling integrating a bifactor model of psychopathology revealed that inhibitory control predicted a shared or general psychopathology dimension, but not ADHD-specific, anxiety-specific, or irritability-specific dimensions. Inhibitory control also showed a significant, selective association with global efficiency in a frontoparietal control network delineated during resting-state functional magnetic resonance imaging. These results support performance-based inhibitory control linked to resting-state brain function as an important predictor of comorbidity in youth psychopathology.

Sleepless nights, sour moods: daily sleep-irritability links in a pediatric clinical sample

BACKGROUND

Sleep, or a lack thereof, is strongly related to mood dysregulation. Although considerable research uses symptom scales to examine this relation, few studies use longitudinal, real-time methods focused on pediatric irritability. This study leveraged an ecological momentary assessment (EMA) protocol, assessing bidirectional associations between momentary irritability symptoms and daily sleep duration in a transdiagnostic pediatric sample enriched for irritability.

METHODS

A total of N = 125 youth (Mage  = 12.58 years, SD = 2.56 years; 74% male; 68.8% White) completed digital, in vivo surveys three times a day for 7 days. For a subset of youth, their parents also completed the EMA protocol. Trait irritability was measured using youth-, parent-, and clinician-report to test its potential moderating effect on the association between sleep duration and momentary irritability.

RESULTS

Results from multilevel modeling dynamically linked sleep to irritability. Specifically, according to youth- and parent-report, decreased sleep duration was associated with increased morning irritability (bs ≤ -.09, ps < .049). A bidirectional association between parent-reported nightly sleep duration and anger was found-increased evening anger related to decreased nightly sleep duration, and decreased sleep duration related to increased morning anger (bs ≤ -.17, ps < .019). Trait irritability moderated this association, which was stronger for more irritable youth (b = -.03, p < .027).

CONCLUSIONS

This study adds to the literature and suggests sleep-irritability dynamics as a potential treatment target.

Multimodal study of the neural sources of error monitoring in adolescents and adults

The ability to monitor performance during a goal-directed behavior differs among children and adults in ways that can be measured with several tasks and techniques. As well, recent work has shown that individual differences in error monitoring moderate temperamental risk for anxiety and that this moderation changes with age. We investigated age differences in neural responses linked to performance monitoring using a multimodal approach. The approach combined functional MRI and source localization of event-related potentials (ERPs) in 12-year-old, 15-year-old, and adult participants. Neural generators of two components related to performance and error monitoring, the N2 and ERN, lay within specific areas of fMRI clusters. Whereas correlates of the N2 component appeared similar across age groups, age-related differences manifested in the location of the generators of the ERN component. The dorsal anterior cingulate cortex (dACC) was the predominant source location for the 12-year-old group; this area manifested posteriorly for the 15-year-old and adult groups. A fMRI-based ROI analysis confirmed this pattern of activity. These results suggest that changes in the underlying neural mechanisms are related to developmental changes in performance monitoring.

Cross-sectional and Longitudinal Associations of Anxiety and Irritability With Adolescents' Neural Responses to Cognitive Conflict

BACKGROUND

Psychiatric symptoms are commonly comorbid in childhood. The ability to disentangle unique and shared correlates of comorbid symptoms facilitates personalized medicine. Cognitive control is implicated broadly in psychopathology, including in pediatric disorders characterized by anxiety and irritability. To disentangle cognitive control correlates of anxiety versus irritability, the current study leveraged both cross-sectional and longitudinal data from early childhood into adolescence.

METHODS

For this study, 89 participants were recruited from a large longitudinal research study on early-life temperament to investigate associations of developmental trajectories of anxiety and irritability symptoms (from ages 2 to 15) as well as associations of anxiety and irritability symptoms measured cross-sectionally at age 15 with neural substrates of conflict and error processing assessed at age 15 using the flanker task.

RESULTS

Results of whole-brain multivariate linear models revealed that anxiety at age 15 was uniquely associated with decreased neural response to conflict across multiple regions implicated in attentional control and conflict adaptation. Conversely, irritability at age 15 was uniquely associated with increased neural response to conflict in regions implicated in response inhibition. Developmental trajectories of anxiety and irritability interacted in relation to neural responses to both error and conflict.

CONCLUSIONS

Our findings suggest that neural correlates of conflict processing may relate uniquely to anxiety and irritability. Continued cross-symptom research on the neural correlates of cognitive control could stimulate advances in individualized treatment for anxiety and irritability during child and adolescent development.

Understanding Irritability in Relation to Anger, Aggression, and Informant in a Pediatric Clinical Population

OBJECTIVE

Despite its clinical relevance to pediatric mental health, the relationship of irritability with anger and aggression remains unclear. We aimed to quantify the relationships between well-validated, commonly used measurements of these constructs and informant effects in a clinically relevant population.

METHOD

A total of 195 children with primary diagnoses of attention-deficit/hyperactivity disorder, disruptive mood dysregulation disorder, or no major disorder and their parents rate irritability, anger, and aggression on measures of each construct. Construct and informant relationships were mapped via multi-trait, multi-method factor analysis.

RESULTS

Parent- and child-reported irritability and child-reported anger are highly associated (r = 0.89) but have some significant differences. Irritability overlaps with outward expression of anger but diverges from anger in anger suppression and control. Aggression has weaker associations with both irritability (r = 0.56) and anger (r = 0.49). Across measures, informant source explains a substantial portion of response variance.

CONCLUSION

Irritability, albeit distinct from aggression, is highly associated with anger, with notable overlap in child-reported outward expression of anger, providing empirical support for formulations of clinical irritability as a proneness to express anger outwardly. Diagnostic and clinical intervention work on this facet of anger can likely translate to irritability. Further research on external validation of divergence of these constructs in anger suppression and control may guide future scale revisions. The proportion of response variance attributable to informant may be an under-recognized confound in clinical research and construct measurement.

ENIGMA-anxiety working group: Rationale for and organization of large-scale neuroimaging studies of anxiety disorders

Anxiety disorders are highly prevalent and disabling but seem particularly tractable to investigation with translational neuroscience methodologies. Neuroimaging has informed our understanding of the neurobiology of anxiety disorders, but research has been limited by small sample sizes and low statistical power, as well as heterogenous imaging methodology. The ENIGMA-Anxiety Working Group has brought together researchers from around the world, in a harmonized and coordinated effort to address these challenges and generate more robust and reproducible findings. This paper elaborates on the concepts and methods informing the work of the working group to date, and describes the initial approach of the four subgroups studying generalized anxiety disorder, panic disorder, social anxiety disorder, and specific phobia. At present, the ENIGMA-Anxiety database contains information about more than 100 unique samples, from 16 countries and 59 institutes. Future directions include examining additional imaging modalities, integrating imaging and genetic data, and collaborating with other ENIGMA working groups. The ENIGMA consortium creates synergy at the intersection of global mental health and clinical neuroscience, and the ENIGMA-Anxiety Working Group extends the promise of this approach to neuroimaging research on anxiety disorders.

Mega-analysis methods in ENIGMA: The experience of the generalized anxiety disorder working group

The ENIGMA group on Generalized Anxiety Disorder (ENIGMA-Anxiety/GAD) is part of a broader effort to investigate anxiety disorders using imaging and genetic data across multiple sites worldwide. The group is actively conducting a mega-analysis of a large number of brain structural scans. In this process, the group was confronted with many methodological challenges related to study planning and implementation, between-country transfer of subject-level data, quality control of a considerable amount of imaging data, and choices related to statistical methods and efficient use of resources. This report summarizes the background information and rationale for the various methodological decisions, as well as the approach taken to implement them. The goal is to document the approach and help guide other research groups working with large brain imaging data sets as they develop their own analytic pipelines for mega-analyses.

Phasic Versus Tonic Irritability: Differential Associations With Attention-Deficit/Hyperactivity Disorder Symptoms

OBJECTIVE

Irritability is a multifaceted construct in pediatric psychopathology. It has been conceptualized as having a phasic dimension and a tonic dimension. Disruptive mood dysregulation disorder is defined by the presence of both dimensions. Severe irritability, or disruptive mood dysregulation disorder, is highly comorbid with attention-deficit/hyperactivity disorder (ADHD). However, it is unknown whether the presence of ADHD modulates the expression of phasic and tonic irritability.

METHOD

A data-driven, latent variable approach was used to examine irritability and ADHD symptoms in a transdiagnostic pediatric sample (N = 489) with primary disruptive mood dysregulation disorder, ADHD, subclinical irritability symptoms, or no diagnosis. Using latent profile analyses, we identified 4 classes: high levels of both irritability and ADHD symptoms, high levels of irritability and moderate levels of ADHD symptoms, moderate levels of irritability and high levels of ADHD symptoms, and low levels of both irritability and ADHD symptoms. Confirmatory factor analysis operationalized phasic irritability and tonic irritability.

RESULTS

As expected, the 2 latent classes characterized by high overall irritability exhibited the highest levels of both phasic and tonic irritability. However, between these 2 high irritability classes, highly comorbid ADHD symptoms were associated with significantly greater phasic irritability than were moderately comorbid ADHD symptoms. In contrast, the 2 high irritability groups did not differ on levels of tonic irritability.

CONCLUSION

These findings suggest that phasic, but not tonic, irritability has a significant association with ADHD symptoms and that phasic and tonic might be distinct, though highly related, irritability dimensions. Future research should investigate potential mechanisms underlying this differential association.

Cortical and subcortical brain structure in generalized anxiety disorder: findings from 28 research sites in the ENIGMA-Anxiety Working Group

The goal of this study was to compare brain structure between individuals with generalized anxiety disorder (GAD) and healthy controls. Previous studies have generated inconsistent findings, possibly due to small sample sizes, or clinical/analytic heterogeneity. To address these concerns, we combined data from 28 research sites worldwide through the ENIGMA-Anxiety Working Group, using a single, pre-registered mega-analysis. Structural magnetic resonance imaging data from children and adults (5-90 years) were processed using FreeSurfer. The main analysis included the regional and vertex-wise cortical thickness, cortical surface area, and subcortical volume as dependent variables, and GAD, age, age-squared, sex, and their interactions as independent variables. Nuisance variables included IQ, years of education, medication use, comorbidities, and global brain measures. The main analysis (1020 individuals with GAD and 2999 healthy controls) included random slopes per site and random intercepts per scanner. A secondary analysis (1112 individuals with GAD and 3282 healthy controls) included fixed slopes and random intercepts per scanner with the same variables. The main analysis showed no effect of GAD on brain structure, nor interactions involving GAD, age, or sex. The secondary analysis showed increased volume in the right ventral diencephalon in male individuals with GAD compared to male healthy controls, whereas female individuals with GAD did not differ from female healthy controls. This mega-analysis combining worldwide data showed that differences in brain structure related to GAD are small, possibly reflecting heterogeneity or those structural alterations are not a major component of its pathophysiology.

A computational network perspective on pediatric anxiety symptoms

BACKGROUND

While taxonomy segregates anxiety symptoms into diagnoses, patients typically present with multiple diagnoses; this poses major challenges, particularly for youth, where mixed presentation is particularly common. Anxiety comorbidity could reflect multivariate, cross-domain interactions insufficiently emphasized in current taxonomy. We utilize network analytic approaches that model these interactions by characterizing pediatric anxiety as involving distinct, inter-connected, symptom domains. Quantifying this network structure could inform views of pediatric anxiety that shape clinical practice and research.

METHODS

Participants were 4964 youths (ages 5-17 years) from seven international sites. Participants completed standard symptom inventory assessing severity along distinct domains that follow pediatric anxiety diagnostic categories. We first applied network analytic tools to quantify the anxiety domain network structure. We then examined whether variation in the network structure related to age (3-year longitudinal assessments) and sex, key moderators of pediatric anxiety expression.

RESULTS

The anxiety network featured a highly inter-connected structure; all domains correlated positively but to varying degrees. Anxiety patients and healthy youth differed in severity but demonstrated a comparable network structure. We noted specific sex differences in the network structure; longitudinal data indicated additional structural changes during childhood. Generalized-anxiety and panic symptoms consistently emerged as central domains.

CONCLUSIONS

Pediatric anxiety manifests along multiple, inter-connected symptom domains. By quantifying cross-domain associations and related moderation effects, the current study might shape views on the diagnosis, treatment, and study of pediatric anxiety.

Rationale and validation of a novel mobile application probing motor inhibition: Proof of concept of CALM-IT

Identification of behavioral mechanisms underlying psychopathology is essential for the development of novel targeted therapeutics. However, this work relies on rigorous, time-intensive, clinic-based laboratory research, making it difficult to translate research paradigms into tools that can be used by clinicians in the community. The broad adoption of smartphone technology provides a promising opportunity to bridge the gap between the mechanisms identified in the laboratory and the clinical interventions targeting them in the community. The goal of the current study is to develop a developmentally appropriate, engaging, novel mobile application called CALM-IT that probes a narrow biologically informed process, inhibitory control. We aim to leverage the rigorous and robust methods traditionally used in laboratory settings to validate this novel mechanism-driven but easily disseminatable tool that can be used by clinicians to probe inhibitory control in the community. The development of CALM-IT has significant implications for the ability to screen for inhibitory control deficits in the community by both clinicians and researchers. By facilitating assessment of inhibitory control outside of the laboratory setting, researchers could have access to larger and more diverse samples. Additionally, in the clinical setting, CALM-IT represents a novel clinical screening measure that could be used to determine personalized courses of treatment based on the presence of inhibitory control deficits.

Attention bias to negative versus non-negative faces is related to negative affectivity in a transdiagnostic youth sample

This study identified a shared pathophysiological mechanism of pediatric anxiety and irritability. Clinically, anxiety and irritability are common, co-occurring problems, both characterized by high-arousal negative affective states. Behaviorally, anxiety and irritability are associated with aberrant threat processing. To build on these findings, we examined eye-tracking measures of attention bias in relation to the unique and shared features of anxiety and irritability in a transdiagnostic sample of youth (n = 97, 58% female, M_age = 13.03, SD_age = 2.82). We measured attention bias to negative versus non-negative emotional faces during a passive viewing task. We employed bifactor analysis to parse the unique and shared variance of anxiety and irritability symptoms from self- and parent-report questionnaires. Negative affectivity is the derived latent factor reflecting shared variance of anxiety and irritability. We found that higher negative affectivity was associated with looking longer at negative versus non-negative faces, reflecting a shared mechanism of anxiety and irritability. This finding suggests that modification of elevated attention to negative emotional faces may represent a common potential treatment target of anxiety and irritability.

Maladaptive Fearlessness: An Examination of the Association Between Subjective Fear Experience and Antisocial Behaviors Linked With Callous Unemotional Traits

The centrality of a fearless temperament as it relates to the construct of psychopathy remains an area of controversy, with some researchers arguing that the relationship between fearless temperament and psychopathy (and associated antisocial behavior) can be explained by shared associations with other core affective and interpersonal traits of psychopathy such as callous-unemotional (CU) traits. The authors investigated real-world subjectively experienced fear in 306 individuals with varying levels of CU traits and antisocial behavior and found that at low levels of subjective fear experience, decreases in subjective fear were associated with greater antisociality. Even after controlling for the positive relationship between CU traits and antisocial behavior, reduced subjectively experienced fear remained a significant predictor of antisocial behavior. These results provide evidence that experienced fear is related to antisocial behavior at lower than average levels of subjectively experienced fear and that this relationship persists after controlling for CU traits.

Bilateral amygdala damage linked to impaired ability to predict others' fear but preserved moral judgements about causing others fear

The amygdala is a subcortical structure implicated in both the expression of conditioned fear and social fear recognition. Social fear recognition deficits following amygdala lesions are often interpreted as reflecting perceptual deficits, or the amygdala's role in coordinating responses to threats. But these explanations fail to capture why amygdala lesions impair both physiological and behavioural responses to multimodal fear cues and the ability to identify them. We hypothesized that social fear recognition deficits following amygdala damage reflect impaired conceptual understanding of fear. Supporting this prediction, we found specific impairments in the ability to predict others' fear (but not other emotions) from written scenarios following bilateral amygdala lesions. This finding is consistent with the suggestion that social fear recognition, much like social recognition of states like pain, relies on shared internal representations. Preserved judgements about the permissibility of causing others fear confirms suggestions that social emotion recognition and morality are dissociable.

Converging Multi-modal Evidence for Implicit Threat-Related Bias in Pediatric Anxiety Disorders

This report examines the relationship between pediatric anxiety disorders and implicit bias evoked by threats. To do so, the report uses two tasks that assess implicit bias to negative-valence faces, the first by eye-gaze and the second by measuring body-movement parameters. The report contrasts task performance in 51 treatment-seeking, medication-free pediatric patients with anxiety disorders and 36 healthy peers. Among these youth, 53 completed an eye-gaze task, 74 completed a body-movement task, and 40 completed both tasks. On the eye-gaze task, patients displayed longer gaze duration on negative relative to non-negative valence faces than healthy peers, F(1, 174) = 8.27, p = .005. In contrast, on the body-movement task, patients displayed a greater tendency to behaviorally avoid negative-valence faces than healthy peers, F(1, 72) = 4.68, p = .033. Finally, implicit bias measures on the two tasks were correlated, r(38) = .31, p = .049. In sum, we found an association between pediatric anxiety disorders and implicit threat bias on two tasks, one measuring eye-gaze and the other measuring whole-body movements. Converging evidence for implicit threat bias encourages future research using multiple tasks in anxiety.

Reduced Multivoxel Pattern Similarity of Vicarious Neural Pain Responses in Psychopathy

Psychopathy is a personality construct characterized by interpersonal callousness, boldness, and disinhibition, traits that vary continuously across the population and are linked to impaired empathic responding to others' distress and suffering. Following suggestions that empathy reflects neural self-other mapping-for example, the similarity of neural responses to experienced and observed pain, measurable at the voxel level-we used a multivoxel approach to assess associations between psychopathy and empathic neural responses to pain. During fMRI scanning, 21 community-recruited participants varying in psychopathy experienced painful pressure stimulation and watched a live video of a stranger undergoing the same stimulation. As total psychopathy, coldheartedness, and self-centered impulsivity increased, multivoxel similarity of vicarious and experienced pain in the left anterior insula decreased, effects that were not observed following an empathy prompt. Our data provide preliminary evidence that psychopathy is characterized by disrupted spontaneous empathic representations of others' pain that may be reduced by instructions to empathize.

Activation in bed nucleus of the stria terminalis (BNST) corresponds to everyday helping

Everyday prosociality includes helping behaviors such as holding doors or giving directions that are spontaneous and low-cost and are performed frequently by the average person. Such behaviors promote a wide array of positive outcomes that include increased well-being, trust, and social capital, but the cognitive and neural mechanisms that support these behaviors are not yet well understood. Whereas costly altruistic responding to others' distress is associated with elevated reactivity in the amygdala, we hypothesized that everyday prosociality would be more closely associated with activation in the bed nucleus of the stria terminalis (BNST), a region of the extended amygdala known for its roles in maintaining vigilance for relevant socio-affective environmental cues and in supporting parental care. One previous study of the neural correlates of everyday prosociality highlighted a functional cluster identified as the septal area but which overlapped with established coordinates of BNST. We used an anatomical mask of BNST (Torrisi et al., 2015) to evaluate the association of BNST activation and daily helping in a sample of 25 adults recruited from the community as well as 23 adults who had engaged in acts of extraordinary altruism. Results found that activation in left BNST during an empathy task predicted everyday helping over a subsequent 14-day period in both samples. BNST activation most strongly predicted helping strangers and proactive helping. We conclude that beyond facilitating care for offspring, activation in BNST may provide a basis for the motivation to engage in a broad array of everyday helping behaviors.

Advancing clinical neuroscience through enhanced tools: Pediatric social anxiety as an example

BACKGROUND

Clinical researchers face challenges when trying to quantify diverse processes engaged during social interactions. We report results from two studies, each demonstrating the potential utility of tools for examining processes engaged during social interactions.

METHOD

In the first study, youth (n = 57) used a smartphone-based tool to rate mood and responses to social events. A subset (n = 20) completed the second, functional magnetic resonance imaging study. This second study related anxiety to error-evoked brain responses in two social conditions-while being observed and when alone. We also combined these tools to bridge clinical, social-contextual, and neural levels of measurement.

RESULTS

Results from the first study showed an association between negatively-perceived social experiences and a range of negative emotions. In the second study there was a positive correlation during error monitoring between social-anxiety severity and context-specific activation of the pregenual anterior cingulate cortex. Finally, during imaging, the perceived quality of peer interactions as assessed using the smartphone-based tool, interacted with social context to predict levels of activation in the hippocampus and superior frontal gyrus.

CONCLUSIONS

By improving measurement, enhanced tools may provide new means for studying relationships among anxiety, brain function, and social interactions.

Callous and uncaring traits are associated with reductions in amygdala volume among youths with varying levels of conduct problems

BACKGROUND

The emergence of callous unemotional (CU) traits, and associated externalizing behaviors, is believed to reflect underlying dysfunction in the amygdala. Studies of adults with CU traits or psychopathy have linked characteristic patterns of amygdala dysfunction to reduced amygdala volume, but studies in youths have not thus far found evidence of similar amygdala volume reductions. The current study examined the association between CU traits and amygdala volume by modeling CU traits and externalizing behavior as independent continuous variables, and explored the relative contributions of callous, uncaring, and unemotional traits.

METHODS

CU traits and externalizing behavior problems were assessed in 148 youths using the Inventory of Callous Unemotional Traits (ICU) and the Child Behavior Checklist (CBCL). For a subset of participants (n = 93), high-resolution T1-weighted images were collected and volume estimates for the amygdala were extracted.

RESULTS

Analyses revealed that CU traits were associated with increased externalizing behaviors and decreased bilateral amygdala volume. These results were driven by the callous and uncaring sub-factors of CU traits, with unemotional traits unrelated to either externalizing behaviors or amygdala volume. Results persisted after accounting for covariation between CU traits and externalizing behaviors. Bootstrap mediation analyses indicated that CU traits mediated the relationship between reduced amygdala volume and externalizing severity.

CONCLUSIONS

These findings provide evidence that callous-uncaring traits account for reduced amygdala volume among youths with conduct problems. These findings provide a framework for further investigation of abnormal amygdala development as a key causal pathway for the development of callous-uncaring traits and conduct problems.

Extraordinary Altruists Exhibit Enhanced Self-Other Overlap in Neural Responses to Distress

Shared neural representations during experienced and observed distress are hypothesized to reflect empathic neural simulation, which may support altruism. But the correspondence between real-world altruism and shared neural representations has not been directly tested, and empathy's role in promoting altruism toward strangers has been questioned. Here, we show that individuals who have performed costly altruism (donating a kidney to a stranger; n = 25) exhibit greater self-other overlap than matched control participants ( n = 27) in neural representations of pain and threat (fearful anticipation) in anterior insula (AI) during an empathic-pain paradigm. Altruists exhibited greater self-other correspondence in pain-related activation in left AI, highlighting that group-level overlap was supported by individual-level associations between empathic pain and firsthand pain. Altruists exhibited enhanced functional coupling of left AI with left midinsula during empathic pain and threat. Results show that heightened neural instantiations of empathy correspond to real-world altruism and highlight limitations of self-report.

Externalizing behavior severity in youths with callous-unemotional traits corresponds to patterns of amygdala activity and connectivity during judgments of causing fear

Callous-unemotional (CU) traits characterize a subgroup of youths with conduct problems who exhibit low empathy, fearlessness, and elevated externalizing behaviors. The current study examines the role of aberrant amygdala activity and functional connectivity during a socioemotional judgment task in youths with CU traits, and links these deficits to externalizing behaviors. Functional magnetic resonance imaging was used to compare neural responses in 18 healthy youths and 30 youths with conduct problems and varying levels of CU traits as they evaluated the acceptability of causing another person to experience each of several emotions, including fear. Neuroimaging analyses examined blood oxygenation level dependent responses and task-dependent functional connectivity. High-CU youths exhibited left amygdala hypoactivation relative to healthy controls and low-CU youths primarily during evaluations of causing others fear. CU traits moderated the relationship between externalizing behavior and both amygdala activity and patterns of functional connectivity. The present data suggest that CU youths' aberrant amygdala activity and connectivity affect how they make judgments about the acceptability of causing others emotional distress, and that these aberrations represent risk factors for externalizing behaviors like rule breaking and aggression. These findings suggest that reducing externalizing behaviors in high-CU youths may require interventions that influence affective sensitivity.

The Reliability and Validity of the Inventory of Callous Unemotional Traits: A Meta-Analytic Review

In the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders, a Limited Prosocial Emotions specifier was added to the conduct disorder diagnostic criteria to designate a subgroup of children who exhibit callous unemotional (CU) traits. The Inventory of Callous Unemotional Traits (ICU) is the only dedicated measure of CU traits and was influential in the development of the Limited Prosocial Emotions specifier. Despite its role in the research and diagnosis of CU traits, some questions have persisted regarding the internal consistency and validity of the ICU and its three subscales: callous, uncaring, and unemotional. Results of a meta-analysis revealed acceptable internal consistency and external validity for total ICU, callous, and uncaring scores, but not unemotional scores. These results support the utility of the total ICU, callous, and uncaring scales, but indicate weaknesses in the scale or construct of unemotionality as it relates to interpersonal callousness, uncaring, and antisociality.

Amygdala-midbrain connectivity indicates a role for the mammalian parental care system in human altruism

Costly altruism benefitting a stranger is a rare but evolutionarily conserved phenomenon. This behaviour may be supported by limbic and midbrain circuitry that supports mammalian caregiving. In rodents, reciprocal connections between the amygdala and the midbrain periaqueductal grey (PAG) are critical for generating protective responses toward vulnerable and distressed offspring. We used functional and structural magnetic resonance imaging to explore whether these regions play a role in supporting costly altruism in humans. We recruited a rare population of altruists, all of whom had donated a kidney to a stranger, and measured activity and functional connectivity of the amygdala and PAG as altruists and matched controls responded to care-eliciting scenarios. When these scenarios were coupled with pre-attentive distress cues, altruists' sympathy corresponded to greater activity in the left amygdala and PAG, and functional connectivity analyses revealed increased coupling between these regions in altruists during this epoch. We also found that altruists exhibited greater fractional anisotropy within the left amygdala-PAG white matter tract. These results, coupled with previous evidence of altruists' increased amygdala-linked sensitivity to distress, are consistent with costly altruism resulting from enhanced care-oriented responses to vulnerability and distress that are supported by recruitment of circuitry that supports mammalian parental care.

The impact of autism spectrum disorder and alexithymia on judgments of moral acceptability

One’s own emotional response toward a hypothetical action can influence judgments of its moral acceptability. Some individuals with autism spectrum disorder (ASD) exhibit atypical emotional processing, and moral judgments. Research suggests, however, that emotional deficits in ASD are due to co-occurring alexithymia, meaning atypical moral judgments in ASD may be due to alexithymia also. Individuals with and without ASD (matched for alexithymia) judged the moral acceptability of emotion-evoking statements and identified the emotion evoked. Moral acceptability judgments were predicted by alexithymia. Crucially, however, this relationship held only for individuals without ASD. While ASD diagnostic status did not directly predict either judgment, those with ASD did not base their moral acceptability judgments on emotional information. Findings are consistent with evidence demonstrating that decision-making is less subject to emotional biases in those with ASD.

This study suggests that typical people base their judgments of the moral acceptability of behavior on their emotional response to that behavior. People with autism spectrum disorder do not seem to use emotional information and may rely more on rules to judge moral acceptability.

Is costly punishment altruistic? Exploring rejection of unfair offers in the Ultimatum Game in real-world altruists

In the Ultimatum Game (UG), incurring a cost to punish inequity is commonly termed altruistic punishment. This behaviour is thought to benefit others if the defector becomes more equitable in future interactions. However, clear connections between punishment in the UG and altruistic behaviours outside the laboratory are lacking. We tested the altruistic punishment hypothesis in a sample of extraordinarily altruistic adults, predicting that if punishing inequity is predictive of altruism more broadly, extraordinary altruists should punish more frequently. Results showed that punishment was not more prevalent in extraordinary altruists than controls. However, a self-reported altruism measure previously linked to peer evaluations but not behaviour, and on which extraordinary altruists and controls did not differ, did predict punishment. These findings support suggestions that altruistic punishment in the UG is better termed costly punishment and may be motivated by social, but not necessarily prosocial, concerns. Results also support prior suggestions that self-reported altruism may not reliably predict altruistic behaviour.

Neural and cognitive characteristics of extraordinary altruists

Altruistic behavior improves the welfare of another individual while reducing the altruist's welfare. Humans' tendency to engage in altruistic behaviors is unevenly distributed across the population, and individual variation in altruistic tendencies may be genetically mediated. Although neural endophenotypes of heightened or extreme antisocial behavior tendencies have been identified in, for example, studies of psychopaths, little is known about the neural mechanisms that support heightened or extreme prosocial or altruistic tendencies. In this study, we used structural and functional magnetic resonance imaging to assess a population of extraordinary altruists: altruistic kidney donors who volunteered to donate a kidney to a stranger. Such donations meet the most stringent definitions of altruism in that they represent an intentional behavior that incurs significant costs to the donor to benefit an anonymous, nonkin other. Functional imaging and behavioral tasks included face-emotion processing paradigms that reliably distinguish psychopathic individuals from controls. Here we show that extraordinary altruists can be distinguished from controls by their enhanced volume in right amygdala and enhanced responsiveness of this structure to fearful facial expressions, an effect that predicts superior perceptual sensitivity to these expressions. These results mirror the reduced amygdala volume and reduced responsiveness to fearful facial expressions observed in psychopathic individuals. Our results support the possibility of a neural basis for extraordinary altruism. We anticipate that these findings will expand the scope of research on biological mechanisms that promote altruistic behaviors to include neural mechanisms that support affective and social responsiveness.

Mediation of the relationship between callous-unemotional traits and proactive aggression by amygdala response to fear among children with conduct problems

IMPORTANCE

Among youths with conduct problems, callous-unemotional (CU) traits are known to be an important determinant of symptom severity, prognosis, and treatment responsiveness. But positive correlations between conduct problems and CU traits result in suppressor effects that may mask important neurobiological distinctions among subgroups of children with conduct problems.

OBJECTIVE

To assess the unique neurobiological covariates of CU traits and externalizing behaviors in youths with conduct problems and determine whether neural dysfunction linked to CU traits mediates the link between callousness and proactive aggression.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional case-control study involved behavioral testing and neuroimaging that were conducted at a university research institution. Neuroimaging was conducted using a 3-T Siemens magnetic resonance imaging scanner. It included 46 community-recruited male and female juveniles aged 10 to 17 years, including 16 healthy control participants and 30 youths with conduct problems with both low and high levels of CU traits.

MAIN OUTCOMES AND MEASURES

Blood oxygenation level-dependent signal as measured via functional magnetic resonance imaging during an implicit face-emotion processing task and analyzed using whole-brain and region of interest-based analysis of variance and multiple-regression analyses.

RESULTS

Analysis of variance revealed no group differences in the amygdala. By contrast, consistent with the existence of suppressor effects, multiple-regression analysis found amygdala responses to fearful expressions to be negatively associated with CU traits (x = 26, y = 0, z = -12; k = 1) and positively associated with externalizing behavior (x = 24, y = 0, z = -14; k = 8) when both variables were modeled simultaneously. Reduced amygdala responses mediated the relationship between CU traits and proactive aggression.

CONCLUSIONS AND RELEVANCE

The results linked proactive aggression in youths with CU traits to hypoactive amygdala responses to emotional distress cues, consistent with theories that externalizing behaviors, particularly proactive aggression, in youths with these traits stem from deficient empathic responses to distress. Amygdala hypoactivity may represent an intermediate phenotype, offering new insights into effective treatment strategies for conduct problems.

Power Plays

Both transient and stable facial cues have evolved as essential features of social communication in humans. Accumulating research links actual and perceived aggression to a higher ratio between the height and bizygomatic width of a person’s face (facial width-to-height ratio [WHR]) and shows that digitally increasing this ratio can alter apparent aggressiveness. We present evidence that facial behaviors associated with anger—the state most closely associated with aggressive intentions—also increase facial WHR, mimicking the facial morphology of aggressive individuals. In Study 1, individuals induced to appear aggressive naturally increased their facial WHR using anger-related facial behaviors. In Study 2, we found that validated anger expressions increased facial WHR and that this change predicts increased attributions of aggressiveness. We also found statistical suggestions that anger-related facial behaviors may serve as cues that overrepresent the expresser’s aggressiveness. Our findings suggest that facial behaviors associated with anger may have emerged to facilitate aggressive encounters.

When psychopathy impairs moral judgments: neural responses during judgments about causing fear

Psychopathy is a disorder characterized by reduced empathy, shallow affect and behaviors that cause victims distress, like threats, bullying and violence. Neuroimaging research in both institutionalized and community samples implicates amygdala dysfunction in the etiology of psychopathic traits. Reduced amygdala responsiveness may disrupt processing of fear-relevant stimuli like fearful facial expressions. The present study links amygdala dysfunction in response to fear-relevant stimuli to the willingness of individuals with psychopathic traits to cause fear in other people. Thirty-three healthy adult participants varying in psychopathic traits underwent whole-brain fMRI scanning while they viewed statements that selectively evoke anger, disgust, fear, happiness or sadness. During scanning, participants judged whether it is morally acceptable to make each statement to another person. Psychopathy was associated with reduced activity in right amygdala during judgments of fear-evoking statements and with more lenient moral judgments about causing fear. No group differences in amygdala function or moral judgments emerged for other emotion categories. Psychopathy was also associated with increased activity in middle frontal gyrus (BA 10) during the task. These results implicate amygdala dysfunction in impaired judgments about causing distress in psychopathy and suggest that atypical amygdala responses to fear in psychopathy extend across multiple classes of stimuli.