Parametric modulation of neural activity by emotion in youth with bipolar disorder, youth with severe mood dysregulation, and healthy volunteers

Neural response to vocal emotional intensity in youth

Previous research has identified regions of the brain that are sensitive to emotional intensity in faces, with some evidence for developmental differences in this pattern of response. However, comparable understanding of how the brain tracks linear variations in emotional prosody is limited-especially in youth samples. The current study used novel stimuli (morphing emotional prosody from neutral to anger/happiness in linear increments) to investigate whether neural response to vocal emotion was parametrically modulated by emotional intensity and whether there were age-related changes in this effect. Participants aged 8-21 years (n = 56, 52% female) completed a vocal emotion recognition task, in which they identified the intended emotion in morphed recordings of vocal prosody, while undergoing functional magnetic resonance imaging. Parametric analyses of whole-brain response to morphed stimuli found that activation in the bilateral superior temporal gyrus (STG) scaled to emotional intensity in angry (but not happy) voices. Multivariate region-of-interest analyses revealed the same pattern in the right amygdala. Sensitivity to emotional intensity did not vary by participants' age. These findings provide evidence for the linear parameterization of emotional intensity in angry vocal prosody within the bilateral STG and right amygdala. Although findings should be replicated, the current results also suggest that this pattern of neural sensitivity may not be subject to strong developmental influences.

Neuropsychological mechanisms of social difficulties in disruptive mood dysregulation disorder versus oppositional defiant disorder

Children with Disruptive Mood Dysregulation Disorder (DMDD) or Oppositional Defiant Disorder (ODD) are characterized by irritability and social difficulties. However, the mechanisms underlying these disorders could be different. This study explores differences in social cognition and executive function (EF) across DMDD and ODD and the influence of these factors and their interaction on social problems in both groups. Children with DMDD (n = 53, Mage = 9.3) or ODD (n = 39, Mage = 9.6) completed neuropsychological tasks measuring social cognition (Theory of Mind and Face-Emotion Recognition) and EF (cognitive flexibility, inhibition, and working memory). Parents reported social problems. More than one-third of the children with DMDD and almost two-thirds of those with ODD showed clear difficulties with Theory of Mind. Most children with DMDD (51-64%) or ODD (67-83%) showed difficulties with EF. In children with DMDD, worse EF (β = -.36) was associated with more social problems, whereas in children with ODD, better EF (β = .44) was associated with more social problems. In those with ODD, but not in those with DMDD, the interaction between social cognition and EF contributed to the explained variance of social problems (β = -1.97). Based on the observed interaction pattern, enhanced EF may lead to increased social problems among children with ODD who also exhibit social cognition difficulties. This study suggests the existence of distinct neuropsychological mechanisms underlying the social issues observed in children with DMDD versus those with ODD.

Facial emotion recognition in children and youth with attention-deficit/hyperactivity disorder and irritability

The ability to recognize emotions evident in people's faces contributes to social functioning and might be affected by ADHD and irritability. Given their high co-occurrence, we examined the relative contribution of ADHD and irritability to facial emotion recognition (FER). We hypothesized that irritability but not ADHD traits would predict increased likelihood of misrecognizing emotions as negative, and that FER performance would explain the association of ADHD and irritability traits with social skills. FER was measured using the Reading the Mind in the Eyes Test (RMET) in children (6-14 years old) referred for ADHD assessment (n = 304) and healthy controls (n = 128). ADHD, irritability and social skills were measured using parent ratings. We used repeated measure logistics regression, comparing the effects across emotion valence of images (i.e., neutral/positive/negative). High irritability but not ADHD diagnosis predicted lower RMET accuracy. ADHD traits predicted lower RMET accuracy in younger but not older participants, whereas irritability predicted poorer accuracy at all ages. ADHD traits predicted lower RMET accuracy across all emotion valences, whereas irritability predicted increased probability of misrecognizing neutral and positive but not negative emotions. Irritability did not increase the probability for erroneously recognizing emotions as negative. ADHD and irritability traits fully explained the association between RMET and social skills. ADHD and irritability traits might impact the ability to identify emotions portrayed in faces. However, irritability traits appear to selectively impair recognition of neutral and positive but not negative emotions. ADHD and irritability are important when examining the link between FER and social difficulties.

Mediating effect of amygdala activity on response to fear vs. happiness in youth with significant levels of irritability and disruptive mood and behavior disorders

Introduction

Irritability, characterized by a tendency to exhibit increased anger, is a common clinical problem in youth. Irritability is a significant clinical issue in youth with various psychiatric diagnoses, especially disruptive behavior, and mood disorders (Attention-Deficit/Hyperactivity Disorder, Oppositional Defiant Disorder, Conduct Disorder, and Disruptive Mood Dysregulation Disorder). Although there have been previous studies focusing on functional alteration in the amygdala related to irritability, there is no comprehensive model between emotional, neuronal, and behavioral characteristics.

Methods

Using an functional magnetic resonance imaging (fMRI) procedure, we investigated the relationships between behavioral irritability, selective impairments in processing facial emotions and the amygdala neural response in youth with increased irritability. Fifty-nine youth with disruptive mood and behavior disorder completed a facial expression processing task with an event-related fMRI paradigm. The severity of irritability was evaluated using the Affective Reactivity Index.

Results

In the result of behavioral data, irritability, and reaction time (RT) differences between interpreting negative (fear) and positive (happiness) facial expressions were positively correlated. In the fMRI result, youth showed higher activation in the right cingulate gyrus, bilateral cerebellum, right amygdala, right precuneus, right superior frontal gyrus, right middle occipital gyrus, and middle temporal gyrus, during the happiness condition vs. fear condition. No brain region exhibited greater activation in the fear than in the happiness conditions. In the result of the mediator analysis, increased irritability was associated with a longer RT toward positive vs. negative facial expressions. Irritability was also positively associated with the difference in amygdala blood oxygen level-dependent responses between the two emotional conditions (happiness > fear). This difference in amygdala activity mediated the interaction between irritability and the RT difference between negative and positive facial expressions.

Discussion

We suggest that impairment in the implicit processing of facial emotional expressions with different valences causes distinct patterns of amygdala response, which correlate with the level of irritability. These results broaden our understanding of the biological mechanism of irritability at the neural level and provide information for the future direction of the study.

Systematic Review and Meta-analysis: Task-based fMRI Studies in Youths With Irritability

OBJECTIVE

Childhood irritability, operationalized as disproportionate and frequent temper tantrums and low frustration tolerance relative to peers, is a transdiagnostic symptom across many pediatric disorders. Studies using task-dependent functional magnetic resonance imaging (fMRI) to probe neural dysfunction in irritability have increased. However, an integrated review summarizing the published methods and synthesized fMRI results remains lacking.

METHOD

We conducted a systematic search using irritability terms and task functional neuroimaging in key databases in March 2021, and identified 30 studies for our systematic review. Sample characteristics and fMRI methods were summarized. A subset of 28 studies met the criteria for extracting coordinate-based data for quantitative meta-analysis. Ten activation-likelihood estimations were performed to examine neural convergence across irritability measures and fMRI task domains.

RESULTS

Systematic review revealed small sample sizes (median = 58, mean age range = 8-16 years) with heterogeneous sample characteristics, irritability measures, tasks, and analytical procedures. Meta-analyses found no evidence for neural activation convergence of irritability across neurocognitive functions related to emotional reactivity, cognitive control, and reward processing, or within each domain. Sensitivity analyses partialing out variances driven by heterogeneous tasks, irritability measures, stimulus types, and developmental ages all yielded null findings. Results were compared with a review on irritability-related structural anomalies from 11 studies.

CONCLUSION

The lack of neural convergence suggests a need for common, standardized irritability assessments and more homogeneous fMRI tasks. Thoughtfully designed fMRI studies probing commonly defined neurocognitive functions may be more fruitful to elucidate the neural mechanisms of irritability. Open science practices, data mining in large neuroscience databases, and standardized analytical methods promote meaningful collaboration in irritability research.

Diagnostic instruments for the assessment of disruptive mood dysregulation disorder: a systematic review of the literature

Disruptive mood dysregulation disorder (DMDD) involves non-episodic irritability and frequent severe temper outbursts in children. Since the inclusion of the diagnosis in the DSM-5, there is no established gold-standard in the assessment of DMDD. In this systematic review of the literature, we provide a synopsis of existing diagnostic instruments for DMDD. Bibliographic databases were searched for any studies assessing DMDD. The systematic search of the literature yielded K = 1167 hits, of which n = 110 studies were included. The most frequently used measure was the Kiddie Schedule for Affective Disorders and Schizophrenia DMDD module (25%). Other studies derived diagnostic criteria from interviews not specifically designed to measure DMDD (47%), chart review (7%), clinical diagnosis without any specific instrument (6%) or did not provide information about the assessment (9%). Three structured interviews designed to diagnose DMDD were used in six studies (6%). Interrater reliability was reported in 36% of studies (ranging from κ = 0.6-1) while other psychometric properties were rarely reported. This systematic review points to a variety of existing diagnostic measures for DMDD with good reliability. Consistent reporting of psychometric properties of recently developed DMDD interviews, as well as their further refinement, may help to ascertain the validity of the diagnosis.

Neurocognitive Correlates of Cerebellar Volumetric Alterations in Youth with Pediatric Bipolar Spectrum Disorders and Bipolar Offspring

BACKGROUND

Emerging evidence points towards the involvement of the cerebellum in the processing of emotions and pathophysiology of mood disorders. However, cerebellar and related cognitive alterations in youth with pediatric bipolar disorder (PBD) and those at high risk to develop the disorder, such as bipolar offspring (BD-OFF) are not clearly defined.

OBJECTIVE

To investigate cerebellar gray and white matter volumes, cognition, and their relationship in youth with PBD and BD-OFF.

METHODS

Thirty youth (7 to 17 years, inclusive) with PBD, 30 BD-OFF and 40 healthy controls (HC) were recruited. Study participants underwent a computer-based cognitive battery assessing affective processing, executive function, attention, psychomotor speed, and learning. Three-tesla MRI scan was performed to assess cerebellar white and gray matter volumes. Cerebellar segmentation was performed with FreeSurfer. Statistical analyses include between-group differences in cognitive domains, cerebellar gray, and white matter volumes. Relationships between cerebellar volumes and cognitive domains were examined.

RESULTS

Youth with PBD showed greater cerebellar gray matter volumes than both BD-OFF and HC, whereas no differences were present between BD-OFF and HC. Both youth with PBD and BD-OFF showed altered processing of negative emotions and a bias towards positive emotions. In youth with PBD and BD-OFF, greater impairment in the processing of emotions correlated with greater cerebellar gray matter volumes.

CONCLUSION

The present findings corroborate hypotheses on cerebellar involvement in the processing of emotions and the pathophysiology of PBD. The presence of cerebellar dysfunction in BD-OFF is unclear.

Context-dependent amygdala-prefrontal connectivity during the dot-probe task varies by irritability and attention bias to angry faces

Irritability, defined as proneness to anger, is among the most common reasons youth are seen for psychiatric care. Youth with irritability demonstrate aberrant processing of anger-related stimuli; however, the neural mechanisms remain unknown. We applied a drift-diffusion model (DDM), a computational tool, to derive a latent behavioral metric of attentional bias to angry faces in youth with varying levels of irritability during functional magnetic resonance imaging (fMRI). We examined associations among irritability, task behavior using a DDM-based index for preferential allocation of attention to angry faces (i.e., extra-decisional time bias; Δt₀), and amygdala context-dependent connectivity during the dot-probe task. Our transdiagnostic sample, enriched for irritability, included 351 youth (ages 8-18; M = 12.92 years, 51% male, with primary diagnoses of either attention deficit/hyperactivity disorder [ADHD], disruptive mood dysregulation disorder [DMDD], an anxiety disorder, or healthy controls). Models accounted for age, sex, in-scanner motion, and co-occurring symptoms of anxiety. Youth and parents rated youth's irritability using the Affective Reactivity Index. An fMRI dot-probe task was used to assess attention orienting to angry faces. In the angry-incongruent vs. angry-congruent contrast, amygdala connectivity with the bilateral inferior frontal gyrus (IFG), insula, caudate, and thalamus/pulvinar was modulated by irritability level and attention bias to angry faces, Δt₀, all ts₃₅₀ > 4.46, ps < 0.001. In youth with high irritability, elevated Δt₀ was associated with a weaker amygdala connectivity. In contrast, in youth with low irritability, elevated Δt₀ was associated with stronger connectivity in those regions. No main effect emerged for irritability. As irritability is associated with reactive aggression, these results suggest a potential neural regulatory deficit in irritable youth who have elevated attention bias to angry cues.

Cerebral Blood Flow and Core Mood Symptoms in Youth Bipolar Disorder: Evidence for Region-Symptom Specificity

OBJECTIVE

Building on prior findings in adults, this study investigated regional cerebral blood flow (CBF) in relation to DSM-5 criterion A symptoms of depression and mania in youth with bipolar disorder (BD).

METHOD

The study recruited 81 youths with BD and 75 healthy controls 13-20 years old. CBF was ascertained using pseudocontinuous arterial spin labeling magnetic resonance imaging. Region-of-interest analyses examined the amygdala, anterior cingulate cortex (ACC), middle frontal gyrus, and global gray matter CBF. The association of criterion A depression and mania symptoms with CBF was examined dimensionally in youth with BD in regression analyses with continuous symptom severity scores. Age and sex were included as covariates. False discovery rate (FDR) was used to correct for 28 tests (4 regions by 7 symptoms; α < .0017). CBF for BD and healthy control groups was compared to give context for findings.

RESULTS

In youth with BD, depressed mood inversely correlated with ACC (β = -0.31, p_uncorrected = .004, p_FDR = .056) and global (β = -0.27, p_uncorrected = .013, p_FDR = .09) CBF. The same pattern was observed for anhedonia (ACC CBF: β = -0.33, p_uncorrected = .004, p_FDR = .056; global CBF: β = -0.29, p_uncorrected = .008, p_FDR = .07). There were no significant findings for manic symptoms or in BD vs healthy control contrasts.

CONCLUSION

The present findings, while not significant after correction for multiple testing, highlight the potential value of focusing on ACC in relation to depressed mood and anhedonia, and demonstrate that CBF is sensitive to depression symptom severity in youth. Lack of findings regarding manic symptoms may relate to the exclusion of fully manic participants in this outpatient sample.

Neural Correlates of the Risk for Schizophrenia and Bipolar Disorder: A Meta-analysis of Structural and Functional Neuroimaging Studies

BACKGROUND

Clinical features and genetics overlap in schizophrenia (SCZ) and bipolar disorder (BD). Identifying brain alterations associated with genetic vulnerability for SCZ and BD could help to discover intermediate phenotypes, quantifiable biological traits with greater prevalence in unaffected relatives (RELs), and early recognition biomarkers in ultrahigh risk populations. However, a comprehensive meta-analysis of structural and functional magnetic resonance imaging (MRI) studies examining relatives of patients with SCZ and BD has not been performed yet.

METHODS

We systematically searched PubMed, Scopus, and Web of Science for structural and functional MRI studies investigating relatives and healthy control subjects. A total of 230 eligible neuroimaging studies (6274 SCZ-RELs, 1900 BD-RELs, 10,789 healthy control subjects) were identified. We conducted coordinate-based activation likelihood estimation meta-analyses on 26 structural MRI and 81 functional MRI investigations, including stratification by task type. We also meta-analyzed regional and global volumetric changes. Finally, we performed a meta-analysis of all MRI studies combined.

RESULTS

Reduced thalamic volume was present in both SCZ and BD RELs. Moreover, SCZ-RELs showed alterations in corticostriatal-thalamic networks, spanning the dorsolateral prefrontal cortex and temporal regions, while BD-RELs showed altered thalamocortical and limbic regions, including the ventrolateral prefrontal, superior parietal, and medial temporal cortices, with frontoparietal alterations in RELs of BD type I.

CONCLUSIONS

Familiarity for SCZ and BD is associated with alterations in the thalamocortical circuits, which may be the expression of the shared genetic mechanism underlying both disorders. Furthermore, the involvement of different prefrontocortical and temporal nodes may be associated with a differential symptom expression in the two disorders.

Underlying mechanisms of disruptive mood dysregulation disorder in children: A systematic review by means of research domain criteria

Background

A systematic overview of underlying mechanisms in the new disruptive mood dysregulation disorder (DMDD) diagnosis is needed. The Research Domain Criteria (RDoC) represent a system of six domains of human functioning, which aims to structure the understanding of the nature of mental illnesses. By means of the RDoC framework, the objective of this systematic review is to synthesize available data on children and youths <18 years suffering from DMDD as reported in peer reviewed papers.

Methods

A literature search guided by PRISMA was conducted using Medline, PsychInfo, and Embase, while the RDoC domains were employed to systematize research findings. Risk of bias in the included studies was examined.

Results

We identified 319 studies. After study selection, we included 29 studies. Twenty-one of these had findings relating to >1 RDoC domain. The risk of bias assessment shows limitations in the research foundation of current knowledge on mechanisms of DMDD.

Discussion

Reviewing self-report, behavior and neurocircuit findings by means of RDoC domains, we suggest that DMDD youths have a negative interpretation bias in social processes and valence systems. In occurrence of a negative stimuli interpretation, aberrant cognitive processing may arise. However, current knowledge of DMDD is influenced by lack of sample diversity and open science practices.

Conclusion

We found the six RDoC domains useful in structuring current evidence of the underlying mechanisms of DMDD. Important opportunities for future studies in this field of research are suggested. In clinical practice, this comprehensive summary on DMDD mechanisms can be used in psychoeducation and treatment plans.

Psychiatric comorbidity and social adjustment difficulties in children with disruptive mood dysregulation disorder: A national epidemiological study

BACKGROUND

We examined correlates, psychiatric comorbidities, and social adjustment difficulties in children with disruptive mood dysregulation disorder (DMDD) from a national epidemiological study in Taiwan.

METHODS

The sample consisted of 4816 children, who were 3^rd, 5^th, and 7^th graders from schools randomly chosen based on the urbanization level in a recent national survey of childhood mental disorders. Among the 4816 children (2520 boys, 52.3%) interviewed using the Kiddie epidemiologic version of the Schedule for Affective Disorders and Schizophrenia (K-SADS-E) for the DSM-5, 30 children were diagnosed as DMDD (23 boys, 76.7%). They and their parents also reported on the Social Adjustment Inventory for Children and Adolescents (SAICA). We conducted regressions for survey data that controlled for stratification and clustering.

RESULTS

The weighted prevalence of DMDD was 0.3~0.76% in Taiwanese children. Lower parental educational levels, male predominance, higher psychiatric comorbidities, and worse self-report school functions (e.g., more behavioral problems with peers) were observed in children with DMDD than those without. Additional analyses revealed that oppositional defiant disorder (ODD) but not DMDD was related to conduct disorder. Children with ODD with or without DMDD had more problems regarding attitudes toward school, academic performance, and parent-child interaction at home than those with DMDD-only.

LIMITATIONS

Small sample size of DMDD.

CONCLUSIONS

DMDD is a rare disorder in the community. Children with DMDD had more psychiatric comorbidities, and subjectively experienced more difficulties than those without. DMDD and ODD both resulted in severe impairment yet in different domains.

Face Emotion Processing in Pediatric Irritability: Neural Mechanisms in a Sample Enriched for Irritability With Autism Spectrum Disorder

OBJECTIVE

Characterizing the pathophysiology of irritability symptoms from a dimensional perspective above and beyond diagnostic boundaries is key to developing mechanism-based interventions that can be applied broadly. Face emotion processing deficits are present in youths with elevated levels of irritability. The present study aimed to identify the neural mechanisms of face emotion processing in a sample enriched for irritability by including youths with high-functioning autism spectrum disorder (HF-ASD).

METHOD

Youths (N = 120, age = 8.3-19.2 years) completed an implicit face emotion task during functional magnetic resonance imaging. We evaluated how irritability, measured dimensionally, above and beyond diagnostic group, relates to whole-brain neural activation and amygdala connectivity in response to face emotions.

RESULTS

Both neural activation and amygdala connectivity differed as a function of irritability level and face emotion in the prefrontal cortex. Youths with higher irritability levels had decreased activation in response to both fearful and happy faces in the left middle frontal gyrus and to happy faces in the left inferior frontal gyrus. Furthermore, increased irritability levels were associated with altered right amygdala connectivity to the left superior frontal gyrus when viewing fearful and sad faces.

CONCLUSION

The neural mechanisms of face emotion processing differ in youths with higher irritability compared to their less irritable peers. The findings suggest that these irritability mechanisms may be common to both typically developing and HF-ASD youths. Understanding the neural mechanisms of pediatric irritability symptoms that cut across diagnostic boundaries may be leveraged for future intervention development.

White Matter Microstructure in Pediatric Bipolar Disorder and Disruptive Mood Dysregulation Disorder

OBJECTIVE

Disruptive mood dysregulation disorder (DMDD) codifies severe, chronic irritability. Youths with bipolar disorder (BD) also present with irritability, but with an episodic course. To date, it is not clear whether aberrant white matter microstructure-a well-replicated finding in BD-can be observed in DMDD and relates to symptoms of irritability.

METHOD

We acquired diffusion tensor imaging data from 118 participants (BD = 36, DMDD = 44, healthy volunteers (HV = 38). Images of fractional anisotropy (FA), axial diffusivity (AD), and radial diffusivity (RD) were processed with tract-based spatial statistics controlling for age and sex. The data were also used to train Gaussian process classifiers to predict diagnostic group.

RESULTS

In BD vs DMDD, FA in the corticospinal tract was reduced. In DMDD vs HV, reductions in FA and AD were confined to the anterior corpus callosum. In BD vs HV, widespread reductions in FA and increased RD were observed. FA in the anterior corpus callosum and corticospinal tract was negatively associated with irritability. The Gaussian process classifier could not discriminate between BD and DMDD, but achieved 68% accuracy in predicting DMDD vs HV and 75% accuracy in predicting BD vs HV.

CONCLUSION

Aberrant white matter microstructure was associated with both categorical diagnosis and the dimension of irritability. Alterations in DMDD were regionally discrete and related to reduced AD. In BD, we observed widespread increases in RD, supporting the hypothesis of altered myelination in BD. These findings will contribute to the pathophysiological understanding of DMDD and its differentiation from BD.

CLINICAL TRIAL REGISTRATION INFORMATION

Studies of Brain Function and Course of Illness in Pediatric Bipolar Disorder; https://clinicaltrials.gov/; NCT00025935; Child & Adolescent Bipolar Disorder Brain Imaging and Treatment Study; https://clinicaltrials.gov/; NCT00006177.

Multi-method assessment of irritability and differential linkages to neurophysiological indicators of attention allocation to emotional faces in young children

Facilitated attention toward angry stimuli (attention bias) may contribute to anger proneness and temper outbursts exhibited by children with high irritability. However, most studies linking attention bias and irritability rely on behavioral measures with limited precision and no studies have explored these associations in young children. The present study explores irritability-related attention biases toward anger in young children (N = 128; ages 4-7 years) engaged in a dot-probe task with emotional faces, as assessed with event-related brain potential (ERP) indices of early selective attention and multi-method assessment of irritability. Irritability assessed via semi-structured clinical interview predicted larger anterior N1 amplitudes to all faces. In contrast, irritability assessed via a laboratory observation paradigm predicted reduced P1 amplitudes to angry relative to neutral faces. These findings suggest that altered early attentional processing occurs in young children with high irritability; however, the nature of these patterns may vary with methodological features of the irritability assessments. Future investigations using different assessment tools may provide greater clarity regarding the underlying neurocognitive correlates of irritability. Such studies may also contribute to the ongoing debates about how to best define and measure irritability across the developmental spectrum in a manner that is most informative for linkage to neural processes.

Neural signatures of the risk for bipolar disorder: A meta-analysis of structural and functional neuroimaging studies

OBJECTIVE

Widespread functional and structural alterations in the brain have been extensively reported in unaffected relatives (RELs) of patients with bipolar disorder (BD) who are at genetic risk for BD. A sufficiently powered meta-analysis of structural (sMRI) and functional magnetic resonance imaging (fMRI) alterations in RELs is still lacking.

METHODS

Functional and structural magnetic resonance imaging studies investigating RELs and healthy controls (HCs) published by July 2017 were included in the meta-analyses. Study procedures were conducted in accordance with the Meta-analysis Of Observational Studies in Epidemiology (MOOSE) guidelines. Random-effects coordinate-based meta-analyses were performed across all the studies per imaging modality using Seed-based d Mapping (SDM). For fMRI studies, meta-analyses were calculated for each task type. For sMRI studies, regional volumetric changes-analyses were estimated using R. Finally, multimodal meta-analyses of structural and functional abnormalities were performed.

RESULTS

Sixty-nine imaging studies (2195 RELs and 3169 HCs) were included in the meta-analyses. RELs showed hyperactivation in the fronto-striatal regions as well as parietal hypoactivation during cognition. Also, activation was increased in the amygdala during emotional processing and in the orbitofrontal cortex during reward, respectively. Frontal and superior temporal cortex were hypertrophic in RELs. The right inferior frontal gyrus (rIFG) showed both increased activation during cognitive tasks and greater volume in RELs.

CONCLUSIONS

Our findings demonstrate that increased brain volume and activation are present in RELs and may represent intermediate phenotypes for the disorder. Furthermore, some neural changes including increased rIFG volume may be associated with the resilience to BD.

Humor Appreciation Involves Parametric and Synchronized Activity in the Medial Prefrontal Cortex and Hippocampus

Humor perception is a ubiquitous phenomenon in human societies. In theories of humor perception, three factors, non-seriousness, social context, and incongruity, have been implicated in humor. In another theory, however, elaboration and reinterpretation of contexts are considered to play a role in eliciting humor. Although the neural correlates of humor appreciation have been investigated using neuroimaging methods, only a few studies have conducted such experiments under natural conditions. In the present study, two functional magnetic resonance imaging experiments, using a comedy movie as a stimulus, were conducted to investigate the neural correlates of humor under natural conditions. The subjects' brain activity was measured while watching and enjoying a movie. In experiment 1, a parametric analysis showed that the medial prefrontal cortex (MPFC) and hippocampus/amygdala had a positive relationship with the subjective rating of funniness. In experiment 2, intersubject correlation was analyzed to investigate synchronized activity across all participants. Signal synchronization that paralleled increased funniness ratings was observed in the MPFC and hippocampus. Thus, it appears that both parametric and synchronized activity in the MPFC and hippocampus are important during humor appreciation. The present study has revealed the brain regions that are predominantly involved in humor sensation under natural condition.

Practitioner Review: Definition, recognition, and treatment challenges of irritability in young people

BACKGROUND

Irritability is one of the most common reasons for referral to child and adolescent mental health services and is the main characteristic of the new diagnosis of disruptive mood dysregulation disorder (DMDD). However, the recognition and management of irritability presents a major challenge in clinical practice and may be partly responsible for the dramatic increase in antipsychotic prescribing in recent years.

METHODS

In this review, we provide up-to-date information on the definition and mechanisms underlying irritability, and its assessment in clinical practice. We aim to discuss the latest research on DMDD, and the presence of severe irritability in the context of other disorders, as well as to recommend a treatment algorithm.

RESULTS

Severe irritability is associated with aberrant reward processing and bias toward threatening stimuli. Several measures are available to easily assess irritability. The recent diagnosis of DMDD captures children whose main problem is severe irritability and differ from those with bipolar disorder in longitudinal outcomes, family history, and behavioral and neural correlates. Treatment of irritability might depend on the context it appears. Indirect evidence suggests that parent management training (PMT) and cognitive behavioral therapy (CBT) are the most supported psychological treatments for irritability.

CONCLUSIONS

Irritability, recognized as a mood problem rather than a purely behavioral manifestation, is a common condition for young people. Practitioners should not ignore irritability as it is associated with substantial morbidity and impairment. Although there are no trials with irritability as main outcome, clinicians can apply several existing pharmacological and psychological interventions for its treatment. Also, new promising approaches relying on pathophysiological findings, such as exposure-based cognitive behavioral therapy techniques and interpretation bias training (IBT), are being currently investigated.

Disruptive Mood Dysregulation Disorder (DMDD): An RDoC perspective

In recent years, there has been much debate regarding the most appropriate diagnostic classification of children exhibiting emotion dysregulation in the form of irritability and severe temper outbursts. Most recently, this has resulted in the addition of a new diagnosis, Disruptive Mood Dysregulation Disorder (DMDD) in the DSM 5. The impetus for including this new disorder was to reduce the number of diagnoses that these children would typically receive; however, there is concern that it has only complicated matters rather than simplifying them. For example, a recent epidemiologic study shows that DMDD cannot be differentiated from oppositional defiant disorder (ODD) based on symptoms alone. Thus, these children are an ideal population in which to apply RDoC constructs in order to obtain greater clarity in terms of underlying processes and ultimately, inform nosology and appropriate interventions. The aim of this article is to provide a foundation for future research by examining extant theoretical and empirical evidence for the role of four key RDoC constructs in DMDD.

Pediatric Irritability: A Systems Neuroscience Approach

Irritability, defined as an increased propensity to exhibit increased anger relative to one's peers, is a common clinical problem in youth. Irritability can be conceptualized as aberrant responses to frustration (where frustration is the emotional response to blocked goal attainment) and/or aberrant 'approach' responses to threat. Irritable youth show hyper-reactivity to threat mediated by dysfunction in amygdala, medial prefrontal cortex (mPFC), anterior cingulate cortex (ACC), insula, striatum, and association cortex. Irritable youth also show abnormalities in reward learning, cognitive control, and responses to frustration. These abnormalities are mediated by circuitry that includes the inferior frontal gyrus (iFG), striatum, ACC, and parietal cortex. Effective treatments for irritability are lacking, but pathophysiological research could lead to more precisely targeted interventions.

Association of Irritability and Anxiety With the Neural Mechanisms of Implicit Face Emotion Processing in Youths With Psychopathology

IMPORTANCE

Psychiatric comorbidity complicates clinical care and confounds efforts to elucidate the pathophysiology of commonly occurring symptoms in youths. To our knowledge, few studies have simultaneously assessed the effect of 2 continuously distributed traits on brain-behavior relationships in children with psychopathology.

OBJECTIVE

To determine shared and unique effects of 2 major dimensions of child psychopathology, irritability and anxiety, on neural responses to facial emotions during functional magnetic resonance imaging.

DESIGN, SETTING, AND PARTICIPANTS

Cross-sectional functional magnetic resonance imaging study in a large, well-characterized clinical sample at a research clinic at the National Institute of Mental Health. The referred sample included youths ages 8 to 17 years, 93 youths with anxiety, disruptive mood dysregulation, and/or attention-deficit/hyperactivity disorders and 22 healthy youths.

MAIN OUTCOMES AND MEASURES

The child's irritability and anxiety were rated by both parent and child on the Affective Reactivity Index and Screen for Child Anxiety Related Disorders, respectively. Using functional magnetic resonance imaging, neural response was measured across the brain during gender labeling of varying intensities of angry, happy, or fearful face emotions. In mixed-effects analyses, the shared and unique effects of irritability and anxiety were tested on amygdala functional connectivity and activation to face emotions.

RESULTS

The mean (SD) age of participants was 13.2 (2.6) years; of the 115 included, 64 were male. Irritability and/or anxiety influenced amygdala connectivity to the prefrontal and temporal cortex. Specifically, irritability and anxiety jointly influenced left amygdala to left medial prefrontal cortex connectivity during face emotion viewing (F4,888 = 9.20; P < .001 for mixed model term). During viewing of intensely angry faces, decreased connectivity was associated with high levels of both anxiety and irritability, whereas increased connectivity was associated with high levels of anxiety but low levels of irritability (Wald χ21 = 21.3; P < .001 for contrast). Irritability was associated with differences in neural response to face emotions in several areas (F2, 888 ≥ 13.45; all P < .001). This primarily occurred in the ventral visual areas, with a positive association to angry and happy faces relative to fearful faces.

CONCLUSIONS AND RELEVANCE

These data extend prior work conducted in youths with irritability or anxiety alone and suggest that research may miss important findings if the pathophysiology of irritability and anxiety are studied in isolation. Decreased amygdala-medial prefrontal cortex connectivity may mediate emotion dysregulation when very anxious and irritable youth process threat-related faces. Activation in the ventral visual circuitry suggests a mechanism through which signals of social approach (ie, happy and angry expressions) may capture attention in irritable youth.

Comparing Brain Morphometry Across Multiple Childhood Psychiatric Disorders

OBJECTIVE

In both children and adults, psychiatric illness is associated with structural brain alterations, particularly in the prefrontal cortex (PFC). However, most studies compare gray matter volume (GMV) in healthy volunteers (HVs) to one psychiatric group. We compared GMV among youth with anxiety disorders, bipolar disorder (BD), disruptive mood dysregulation disorder (DMDD), attention-deficit/hyperactivity disorder (ADHD), and HVs.

METHOD

3-Tesla T1-weighted magnetic resonance imaging scans were acquired in 184 youths (39 anxious, 20 BD, 52 DMDD, 20 ADHD, and 53 HV). Voxel-based morphometry analyses were conducted. One-way analysis of variance tested GMV differences with whole-brain familywise error (p < .05) correction; secondary, exploratory whole-brain analyses used a threshold of p < .001, ≥200 voxels. Given recent frameworks advocating dimensional approaches in psychopathology research, we also tested GMV associations with continuous anxiety, irritability, and inattention symptoms.

RESULTS

Specificity emerged in the left dorsolateral PFC (dlPFC), which differed among youth with BD, anxiety, and HVs; GMV was increased in youth with anxiety, but decreased in BD, relative to HVs. Secondary analyses revealed BD-specific GMV decreases in the right lateral PFC, right dlPFC, and dorsomedial PFC, and also anxiety-specific GMV increases in the left dlPFC, right ventrolateral PFC, frontal pole, and right parahippocampal gyrus/lingual gyrus. Both BD and DMDD showed decreased GMV relative to HVs in the right dlPFC/superior frontal gyrus. GMV was not associated with dimensional measures of anxiety, irritability, or ADHD symptoms.

CONCLUSION

Both disorder-specific and shared GMV differences manifest in pediatric psychopathology. Some differences were specific to anxiety disorders, others specific to BD, and others shared between BD and DMDD. Further developmental research might map commonalities and differences of structure and function in diverse pediatric psychopathologies.

Deactivation in anterior cingulate cortex during facial processing in young individuals with high familial risk and early development of depression: fMRI findings from the Scottish Bipolar Family Study

BACKGROUND

Studies have identified perturbations in facial processing in bipolar disorder and major depressive disorder (MDD), but their relationship to genetic risk and early development of illness is unclear.

METHODS

The Scottish Bipolar Family Study is a prospective longitudinal investigation examining young individuals (age 16-25) at familial risk of mood disorder. Participants underwent functional MRI using an implicit facial processing task employing angry and neutral faces. An explicit facial expression recognition task was completed outside the scanner. Clinical outcomes obtained 2 years after the scan were used to categorise participants into controls (n = 54), high-risk individuals who had developed MDD (HR MDD; n = 30) and high-risk individuals who remained well (HR Well, n = 43).

RESULTS

All groups demonstrated activation patterns typically observed during facial processing, including activation of the amygdala, hippocampus, fusiform gyrus and middle frontal regions. Notably, the HR MDD group showed reduced activation of the anterior cingulate gyrus versus both the control and HR Well group for angry faces, and versus the HR Well group for neutral faces. Outside the scanner, the HR MDD group was less accurate in recognising fearful expressions than the HR Well group.

CONCLUSIONS

Here, we demonstrate functional abnormalities of the anterior cingulate cortex alongside facial emotional recognition deficits in high-risk individuals in the early stages of depression compared with both controls and at-risk individuals who remained well. These neural changes were associated with a current or future diagnosis of MDD and were not simply associated with increased familial risk.

Neural Correlates of Irritability in Disruptive Mood Dysregulation and Bipolar Disorders

OBJECTIVE

Bipolar disorder and disruptive mood dysregulation disorder (DMDD) are clinically and pathophysiologically distinct, yet irritability can be a clinical feature of both illnesses. The authors examine whether the neural mechanisms mediating irritability differ between bipolar disorder and DMDD, using a face emotion labeling paradigm because such labeling is deficient in both patient groups. The authors hypothesized that during face emotion labeling, irritability would be associated with dysfunctional activation in the amygdala and other temporal and prefrontal regions in both disorders, but that the nature of these associations would differ between DMDD and bipolar disorder.

METHOD

During functional MRI acquisition, 71 youths (25 with DMDD, 24 with bipolar disorder, and 22 healthy youths) performed a labeling task with happy, fearful, and angry faces of varying emotional intensity.

RESULTS

Participants with DMDD and bipolar disorder showed similar levels of irritability and did not differ from each other or from healthy youths in face emotion labeling accuracy. Irritability correlated with amygdala activity across all intensities for all emotions in the DMDD group; such correlation was present in the bipolar disorder group only for fearful faces. In the ventral visual stream, associations between neural activity and irritability were found more consistently in the DMDD group than in the bipolar disorder group, especially in response to ambiguous angry faces.

CONCLUSIONS

These results suggest diagnostic specificity in the neural correlates of irritability, a symptom of both DMDD and bipolar disorder. Such evidence of distinct neural correlates suggests the need to evaluate different approaches to treating irritability in the two disorders.

The Status of Irritability in Psychiatry: A Conceptual and Quantitative Review

OBJECTIVE

Research and clinical interest in irritability have been on the rise in recent years. Yet several questions remain about the status of irritability in psychiatry, including whether irritability can be differentiated from other symptoms, whether it forms a distinct disorder, and whether it is a meaningful predictor of clinical outcomes. In this article, we try to answer these questions by reviewing the evidence on how reliably irritability can be measured and its validity.

METHOD

We combine a narrative and systematic review and meta-analysis of studies. For the systematic review and meta-analysis, we searched studies in PubMed and Web of Science based on preselected criteria. A total of 163 articles were reviewed, and 24 were included.

RESULTS

We found that irritability forms a distinct dimension with substantial stability across time, and that it is specifically associated with depression and anxiety in longitudinal studies. Evidence from genetic studies reveals that irritability is moderately heritable, and its overlap with depression is explained mainly by genetic factors. Behavioral and neuroimaging studies show that youth with persistent irritability exhibit altered activations in the amygdala, striatum, and frontal regions compared with age-matched healthy volunteers. Most knowledge about the treatment of irritability is based on effects of treatment on related conditions or post hoc analyses of trial data.

CONCLUSION

We identify a number of research priorities including innovative experimental designs and priorities for treatment studies, and conclude with recommendations for the assessment of irritability for researchers and clinicians.

Happy heart syndrome: role of positive emotional stress in takotsubo syndrome

Aims

Takotsubo syndrome (TTS) is typically provoked by negative stressors such as grief, anger, or fear leading to the popular term ‘broken heart syndrome’. However, the role of positive emotions triggering TTS remains unclear. The aim of the present study was to analyse the prevalence and characteristics of patients with TTS following pleasant events, which are distinct from the stressful or undesirable episodes commonly triggering TTS.

Methods and results

Takotsubo syndrome patients with preceding pleasant events were compared to those with negative emotional triggers from the International Takotsubo Registry. Of 1750 TTS patients, we identified a total of 485 with a definite emotional trigger. Of these, 4.1% (n = 20) presented with pleasant preceding events and 95.9% (n = 465) with unequivocal negative emotional events associated with TTS. Interestingly, clinical presentation of patients with ‘happy heart syndrome’ was similar to those with the ‘broken heart syndrome’ including symptoms such as chest pain [89.5% (17/19) vs. 90.2% (412/457), P = 1.0]. Similarly, electrocardiographic parameters, laboratory findings, and 1-year outcome did not differ. However, in a post hoc analysis, a disproportionate higher prevalence of midventricular involvement was noted in ‘happy hearts’ compared with ‘broken hearts’ (35.0 vs. 16.3%, P = 0.030).

Conclusion

Our data illustrate that TTS can be triggered by not only negative but also positive life events. While patient characteristics were similar between groups, the midventricular TTS type was more prevalent among the ‘happy hearts’ than among the ‘broken hearts’. Presumably, despite their distinct nature, happy and sad life events may share similar final common emotional pathways, which can ultimately trigger TTS.

Altered neural function to happy faces in adolescents with and at risk for depression

BACKGROUND

There is accumulating evidence of alterations in neural circuitry underlying the processing of social-affective information in adolescent Major Depressive Disorder (MDD). However the extent to which such alterations are present in youth at risk for mood disorders remains unclear.

METHOD

Whole-brain blood oxygenation level-dependent task responses and functional connectivity using generalized psychophysiological interaction (gPPI) analyses to mild and intense happy face stimuli was examined in 29 adolescents with MDD (MDD; M age, 16.0, S.D. 1.2 years), 38 healthy adolescents at risk of a mood disorder, by virtue of having a parent diagnosed with either Bipolar Disorder (BD) or MDD (Mood-risk; M age 13.4, S.D. 2.5 years) and 43 healthy control adolescents, having parents with no psychiatric disorder (HC; M age 14.6, S.D. 2.2 years).

RESULTS

Relative to HC adolescents, Mood-risk adolescents showed elevated right dorsolateral prefrontal cortex (DLPFC) activation to 100% intensity happy (vs. neutral) faces and concomitant lowered ventral putamen activity to 50% intensity happy (vs. neutral) faces. gPPI analyses revealed that MDD adolescents showed significantly lower right DLPFC functional connectivity with the ventrolateral PFC (VLPFC) compared to HC to all happy faces.

LIMITATIONS

The current study is limited by the smaller number of healthy offspring at risk for MDD compared to BD.

CONCLUSIONS

Because Mood-risk adolescents were healthy at the time of the scan, elevated DLPFC and lowered ventral striatal activity in Mood-risk adolescents may be associated with risk or resiliency. In contrast, altered DLPFC-VLPFC functional connectivity in MDD adolescents may be associated with depressed mood state. Such alterations may affect social-affective development and progression to a mood disorder in Mood-risk adolescents. Future longitudinal follow-up studies are needed to directly answer this research question.

An Open Pilot Study of Training Hostile Interpretation Bias to Treat Disruptive Mood Dysregulation Disorder

OBJECTIVE

Irritability in disruptive mood dysregulation disorder (DMDD) may be associated with a biased tendency to judge ambiguous facial expressions as angry. We conducted three experiments to explore this bias as a treatment target. We tested: 1) whether youth with DMDD express this bias; 2) whether judgment of ambiguous faces can be altered in healthy youth by training; and 3) whether such training in youth with DMDD is associated with reduced irritability and associated changes in brain function.

METHODS

Participants in all experiments made happy versus angry judgments of faces that varied along a happy to angry continuum. These judgments were used to quantify a "balance point," the facial expression at which a participant's judgment switches from predominantly happy to predominantly angry. We first compared balance points in youth with DMDD (n = 63) versus healthy youth (n = 26). We then conducted a double-blind, randomized controlled trial of active versus sham balance-point training in 19 healthy youth. Finally, we piloted open, active balance-point training in 14 youth with DMDD, with 10 completing an implicit functional MRI (fMRI) face-emotion processing task.

RESULTS

Relative to healthy youth, DMDD youth manifested a shifted balance point, expressed as a tendency to classify ambiguous faces as angry rather than happy. In both healthy and DMDD youth, active training is associated with a shift in balance point toward more happy judgments. In DMDD, evidence suggests that active training may be associated with decreased irritability and changes in activation in the lateral orbitofrontal cortex.

CONCLUSIONS

These results set the stage for further research on computer-based treatment targeting interpretation bias of angry faces in DMDD. Such treatment may decrease irritability and alter neural responses to subtle expressions of happiness and anger.

Neural correlates of masked and unmasked face emotion processing in youth with severe mood dysregulation

Reproducibility of results is important in improving the robustness of conclusions drawn from research, particularly in functional magnetic resonance imaging (fMRI). In this study, we aim to replicate a previous study on the neural correlates of face emotion processing above and below awareness level using an independent sample of youth with severe mood dysregulation (SMD) and healthy volunteers (HV). We collected fMRI data in 17 SMD and 20 HV, using an affective priming paradigm with masked (17 ms) and unmasked (187 ms) faces (angry, happy, neutral, blank oval). When processing masked and unmasked angry faces, SMD patients exhibited increased activation in the parahippocampal gyrus (PHG) and superior temporal gyrus relative to HV. When processing masked and unmasked happy faces, SMD patients showed decreased activation in the insula, PHG and thalamus compared with HV. During masked face processing in general across emotions, youth with SMD showed greater ventromedial prefrontal cortex (vmPFC) activation relative to HV. Perturbed activation in emotion processing areas (e.g. insula, PHG, superior temporal gyrus and thalamus) manifests as hyper-sensitivity toward negative emotions and hypo-sensitivity toward positive emotions may be important in the etiology and maintenance of irritability, aggression and depressive symptoms in SMD. vmPFC dysfunction may mediate over-reactivity to face emotions associated with irritability.

Genetic variation in the G72 gene is associated with increased frontotemporal fiber tract integrity

G72 (syn. DAOA, D-amino acid oxidase activator) is a susceptibility gene for both schizophrenia and bipolar disorder. Diffusion tensor imaging studies hint at changes in fiber tract integrity in both disorders. We aimed to investigate whether a G72 susceptibility haplotype causes changes in fiber tract integrity in young healthy subjects. We compared fractional anisotropy in 47 subjects that were either homozygous for the M23/M24 risk haplotype (n = 20) or homozygous for M23(rs3918342)/M24(rs1421292) wild type (n = 27) using diffusion tensor imaging with 3 T. Tract-based spatial statistics, a method especially developed for diffusion data analysis, was used to delineate the major fiber tracts. We found clusters of increased FA values in homozygous risk haplotype carriers in the right periinsular region and in the right inferior parietal lobe (IPL). We did not find clusters indicating decreased FA values. The insula and the IPL have been implicated in both schizophrenia and bipolar pathophysiology. Increased FA values might reflect changes in dendritic morphology as previously described by in vitro studies. These findings further corroborate the hypothesis that a shared gene pool between schizophrenia and bipolar disorder might lead to neuroanatomic changes that confer an unspecific vulnerability for both disorders.

Aberrant amygdala intrinsic functional connectivity distinguishes youths with bipolar disorder from those with severe mood dysregulation

It remains unclear the degree to which youths with episodic mania (bipolar disorder; BD) vs. those with chronic, severe irritability (severe mood dysregulation, SMD) should be placed in similar or distinct diagnostic groups. Addressing this clinically meaningful question requires greater understanding of the neural alterations underlying both disorders. We evaluated resting state functional magnetic resonance imaging data of 53 youths (14 BD, 20 healthy volunteers (HV), and 19 SMD, ages 9-18.5 years). Seed regions of interest were the bilateral basolateral, superficial and centromedial amygdala, defined using the Juelich probabilistic atlas. We found a significant between-group difference in functional connectivity between the left basolateral amygdala and the medial aspect of the left frontal pole plus the posterior cingulate/precuneus. This finding was driven by hyperconnectivity among BD vs. HV or SMD youths. As with earlier data, these findings suggest that the pathophysiology of BD and SMD may differ.

Parametric modulation of neural activity during face emotion processing in unaffected youth at familial risk for bipolar disorder

OBJECTIVES

Both patients with pediatric bipolar disorder (BD) and unaffected youth at familial risk (AR) for the illness show impairments in face emotion labeling. Few studies, however, have examined brain regions engaged in AR youth when processing emotional faces. Moreover, studies have yet to explore neural responsiveness to subtle changes in face emotion in AR youth.

METHODS

Sixty-four unrelated youth, including 20 patients with BD, 15 unaffected AR youth, and 29 healthy comparisons (HC), completed functional magnetic resonance imaging. Neutral faces were morphed with angry or happy faces in 25% intervals. In specific phases of the task, youth alternatively made explicit (hostility) or implicit (nose width) ratings of the faces. The slope of blood oxygenated level-dependent activity was calculated across neutral to angry and neutral to happy face stimuli.

RESULTS

Behaviorally, both subjects with BD (p ≤ 0.001) and AR youth (p ≤ 0.05) rated faces as less hostile relative to HC. Consistent with this, in response to increasing anger on the face, patients with BD and AR youth showed decreased modulation in the amygdala and inferior frontal gyrus (IFG; BA 46) compared to HC (all p ≤ 0.05). Amygdala dysfunction was present across both implicit and explicit rating conditions, but IFG modulation deficits were specific to the explicit condition. With increasing happiness, AR youth showed aberrant modulation in the IFG, which was also sensitive to task demands (all p ≤ 0.05).

CONCLUSIONS

Decreased amygdala and IFG modulation in patients with BD and AR youth may be pathophysiological risk markers for BD, and may underlie the social cognition and face emotion labeling deficits observed in BD and AR youth.

Abnormal deactivation of the inferior frontal gyrus during implicit emotion processing in youth with bipolar disorder: attenuated by medication

Previous neuroimaging studies of youth with bipolar disorder (BD) have identified abnormalities in emotion regulation circuitry. Using data from the Longitudinal Assessment of Manic Symptoms Cohort (a clinical sample recruited for behavioral and emotional dysregulation), we examined the impact of BD and medication on activation in these regions. Functional neuroimaging data were obtained from 15 youth with BD who currently were unmedicated with a mood stabilizer or antipsychotic (U-BD), 19 youth with medicated BD (M-BD), a non-bipolar clinical sample with high rates of disruptive behavioral disorders (non-BD, n = 59), and 29 healthy controls (HC) while they were shown task-irrelevant morphing emotional faces and shapes. Whole brain analysis was used to identify clusters that showed differential activation to emotion vs. shapes across group. To assess pair-wise comparisons and potential confounders, mean activation data were extracted only from clusters within regions previously implicated in emotion regulation (including amygdala and ventral prefrontal regions). A cluster in the right inferior frontal gyrus (IFG) showed group differences to emotion vs. shapes (159 voxels, corrected p < .05). Within this cluster, U-BD youth showed decreased activation relative to HC (p = .007) and non-BD (p = .004) youth. M-BD also showed decreased activation in this cluster relative to HC and non-BD youth, but these differences were attenuated. Results were specific to negative emotions, and not found with happy faces. IFG findings were not explained by other medications (e.g. stimulants) or diagnoses. Compared to both HC and a non-BD sample, U-BD is associated with abnormally decreased right IFG activation to negative emotions.

Filling the gap: relationship between the serotonin-transporter-linked polymorphic region and amygdala activation

The alleged association between the serotonin-transporter-linked polymorphic region (5-HTTLPR) and amygdala activation forms a cornerstone of the common view that carrying the short allele of this polymorphism is a potential risk factor for affective disorders. The authors of a recent meta-analysis showed that this association is statistically significant (Hedges's g = 0.35) but warned that estimates might be distorted because of publication bias. Here, we report a replication study of this relationship in 120 participants. We failed to find an association of 5-HTTLPR variation with amygdala activation during a widely used emotional-face-matching paradigm. Moreover, when we conducted a meta-analysis that included unpublished studies and data from the current study, the pooled meta-analytic effect size was no longer significant (g = 0.20, p = .06). These findings cast doubt on previously reported substantial effects, suggesting that the 5-HTTLPR-amygdala association is either much smaller than previously thought, conditional on other factors, or nonexistent.

The developmental psychopathology of irritability

Chronic, severe irritability is common in childhood and is very impairing. Furthermore, childhood irritability predicts suicidality, social impairment, and depressive and anxiety disorders in adulthood. Focusing on both normative and pathologic development, we review the construct of irritability from its origins in aggression and disruptive behavior research to its contemporary relevance for affective psychopathology. We then describe two broad neurocognitive systems that show promise in differentiating irritable from nonirritable youths: aberrant processing of emotional stimuli and impaired context-sensitive regulation. We suggest behavioral, neurocognitive, and physiologic measures that may aid in studying severe irritability and assessing its therapeutics. Finally, we argue for therapeutic trials targeting severe irritability that address emotional aspects of irritability in addition to the associated disruptive behavior.

Attention bias to threat faces in severe mood dysregulation

BACKGROUND

We used a dot-probe paradigm to examine attention bias toward threat (i.e., angry) and happy face stimuli in severe mood dysregulation (SMD) versus healthy comparison (HC) youth. The tendency to allocate attention to threat is well established in anxiety and other disorders of negative affect. SMD is characterized by the negative affect of irritability, and longitudinal studies suggest childhood irritability predicts adult anxiety and depression. Therefore, it is important to study pathophysiologic connections between irritability and anxiety disorders.

METHODS

SMD patients (N = 74) and HC youth (N = 42) completed a visual probe paradigm to assess attention bias to emotional faces. Diagnostic interviews were conducted and measures of irritability and anxiety were obtained in patients.

RESULTS

SMD youth differed from HC youth in having a bias toward threatening faces (P < .01). Threat bias was positively correlated with the severity of the SMD syndrome and depressive symptoms; degree of threat bias did not differ between SMD youth with and without co-occurring anxiety disorders or depression. SMD and HC youth did not differ in bias toward or away from happy faces.

CONCLUSIONS

SMD youth demonstrate an attention bias toward threat, with greater threat bias associated with higher levels of SMD symptom severity. Our findings suggest that irritability may share a pathophysiological link with anxiety and depressive disorders. This finding suggests the value of exploring further whether attention bias modification treatments that are effective for anxiety are also helpful in the treatment of irritability.

Fronto-limbic-striatal dysfunction in pediatric and adult patients with bipolar disorder: impact of face emotion and attentional demands

BACKGROUND

Research in bipolar disorder (BD) implicates fronto-limbic-striatal dysfunction during face emotion processing but it is unknown how such dysfunction varies by task demands, face emotion and patient age.

METHOD

During functional magnetic resonance imaging (fMRI), 181 participants, including 62 BD (36 children and 26 adults) and 119 healthy comparison (HC) subjects (57 children and 62 adults), engaged in constrained and unconstrained processing of emotional (angry, fearful, happy) and non-emotional (neutral) faces. During constrained processing, subjects answered questions focusing their attention on the face; this was processed either implicitly (nose width rating) or explicitly (hostility; subjective fear ratings). Unconstrained processing consisted of passive viewing.

RESULTS

Pediatric BD rated neutral faces as more hostile than did other groups. In BD patients, family-wise error (FWE)-corrected region of interest (ROI) analyses revealed dysfunction in the amygdala, inferior frontal gyrus (IFG), anterior cingulate cortex (ACC) and putamen. Patients with BD showed amygdala hyperactivation during explicit processing (hostility ratings) of fearful faces and passive viewing of angry and neutral faces but IFG hypoactivation during implicit processing of neutral and happy faces. In the ACC and striatum, the direction of dysfunction varied by task demand: BD demonstrated hyperactivation during unconstrained processing of angry or neutral faces but hypoactivation during constrained processing (implicit or explicit) of angry, neutral or happy faces.

CONCLUSIONS

Findings suggest amygdala hyperactivation in BD while processing negatively valenced and neutral faces, regardless of attentional condition, and BD IFG hypoactivation during implicit processing. In the cognitive control circuit involving the ACC and putamen, BD neural dysfunction was sensitive to task demands.

Neural response during explicit and implicit face processing varies developmentally in bipolar disorder

Both children and adults with bipolar disorder (BD) exhibit face emotion labeling deficits and neural circuitry dysfunction in response to emotional faces. However, few studies have compared these groups directly to distinguish effects of age and diagnosis. Such studies are important to begin to elucidate the developmental trajectory of BD and facilitate its diagnosis, prevention and treatment. This functional magnetic resonance imaging study compares 41 individuals with BD (19 children; 22 adults) and 44 age-matched healthy individuals (25 children; 19 adults) when making explicit or implicit judgments about angry or happy face morphs across a range of emotion intensity. Linear trend analyses revealed that BD patients, irrespective of age, failed to recruit the amygdala in response to increasing angry face. This finding was no longer significant when the group was restricted to euthymic youth or those without comorbid attention deficit hyperactivity disorder although this may reflect low statistical power. Deficits in subgenual anterior cingulate modulation were observed in both patient groups but were related to implicit processing for child patients and explicit processing for adult patients. Abnormalities in face emotion labeling and the circuitry mediating it may be biomarkers of BD that are present across development.

Irritability in children and adolescents: past concepts, current debates, and future opportunities

Irritability is defined as a low threshold to experience anger in response to frustration. It is one of the most common symptoms in youth and is part of the clinical presentation of several disorders. Irritability can present early in life and is a predictor of long-term psychopathology; yet, the diagnostic status of irritability is a matter of intense debate. In the present article, we address two main components of the debate regarding irritability in youth: the misdiagnosis of chronic irritability as pediatric bipolar disorder, and the proposal of a new diagnosis in the DSM-5, disruptive mood dysregulation disorder, whose defining symptoms are chronic irritability and temper outbursts.

Impaired fixation to eyes during facial emotion labelling in children with bipolar disorder or severe mood dysregulation

BACKGROUND

Children with bipolar disorder (BD) or severe mood dysregulation (SMD) show behavioural and neural deficits during facial emotion processing. In those with other psychiatric disorders, such deficits have been associated with reduced attention to eye regions while looking at faces.

METHODS

We examined gaze fixation patterns during a facial emotion labelling task among children with pediatric BD and SMD and among healthy controls. Participants viewed facial expressions with varying emotions (anger, fear, sadness, happiness, neutral) and emotional levels (60%, 80%, 100%) and labelled emotional expressions.

RESULTS

Our study included 22 children with BD, 28 with SMD and 22 controls. Across all facial emotions, children with BD and SMD made more labelling errors than controls. Compared with controls, children with BD spent less time looking at eyes and made fewer eye fixations across emotional expressions. Gaze patterns in children with SMD tended to fall between those of children with BD and controls, although they did not differ significantly from either of these groups on most measures. Decreased fixations to eyes correlated with lower labelling accuracy in children with BD, but not in those with SMD or in controls.

LIMITATIONS

Most children with BD were medicated, which precluded our ability to evaluate medication effects on gaze patterns.

CONCLUSION

Facial emotion labelling deficits in children with BD are associated with impaired attention to eyes. Future research should examine whether impaired attention to eyes is associated with neural dysfunction. Eye gaze deficits in children with BD during facial emotion labelling may also have treatment implications. Finally, children with SMD exhibited decreased attention to eyes to a lesser extent than those with BD, and these equivocal findings are worthy of further study.

Neural circuitry of masked emotional face processing in youth with bipolar disorder, severe mood dysregulation, and healthy volunteers

Youth with bipolar disorder (BD) and those with severe, non-episodic irritability (severe mood dysregulation, SMD) show face-emotion labeling deficits. These groups differ from healthy volunteers (HV) in neural responses to emotional faces. It is unknown whether awareness is required to elicit these differences. We compared activation in BD (N=20), SMD (N=18), and HV (N=22) during "Aware" and "Non-aware" priming of shapes by emotional faces. Subjects rated how much they liked the shape. In aware, a face (angry, fearful, happy, neutral, blank oval) appeared (187 ms) before the shape. In non-aware, a face appeared (17 ms), followed by a mask (170 ms), and shape. A Diagnosis-by-Awareness-by-Emotion ANOVA was not significant. There were significant Diagnosis-by-Awareness interactions in occipital regions. BD and SMD showed increased activity for non-aware vs. aware; HV showed the reverse pattern. When subjects viewed angry or neutral faces, there were Emotion-by-Diagnosis interactions in face-emotion processing regions, including the L precentral gyrus, R posterior cingulate, R superior temporal gyrus, R middle occipital gyrus, and L medial frontal gyrus. Regardless of awareness, BD and SMD differ in activation patterns from HV and each other in multiple brain regions, suggesting that BD and SMD are distinct developmental mood disorders.

Cortical activation deficits during facial emotion processing in youth at high risk for the development of substance use disorders

BACKGROUND

Recent longitudinal studies demonstrate that addiction risk may be influenced by a cognitive, affective and behavioral phenotype that emerges during childhood. Relatively little research has focused on the affective or emotional risk components of this high-risk phenotype, including the relevant neurobiology.

METHODS

Non-substance abusing youth (N=19; mean age=12.2) with externalizing psychopathology and paternal history of a substance use disorder and demographically matched healthy comparisons (N=18; mean age=11.9) were tested on a facial emotion matching task during functional MRI. This task involved matching faces by emotions (angry, anxious) or matching shape orientation.

RESULTS

High-risk youth exhibited increased medial prefrontal, precuneus and occipital cortex activation compared to the healthy comparison group during the face matching condition, relative to the control shape condition. The occipital activation correlated positively with parent-rated emotion regulation impairments in the high-risk group.

CONCLUSIONS

These findings suggest a preexisting abnormality in cortical activation in response to facial emotion matching in youth at high risk for the development of problem drug or alcohol use. These cortical deficits may underlie impaired affective processing and regulation, which in turn may contribute to escalating drug use in adolescence.

Elevated amygdala responses to emotional faces in youths with chronic irritability or bipolar disorder

A major controversy in child psychiatry is whether bipolar disorder (BD) presents in children as severe, non-episodic irritability (operationalized here as severe mood dysregulation, SMD), rather than with manic episodes as in adults. Both classic, episodic BD and SMD are severe mood disorders characterized by deficits in processing emotional stimuli. Neuroimaging techniques can be used to test whether the pathophysiology mediating these deficits are similar across the two phenotypes. Amygdala dysfunction during face emotion processing is well-documented in BD, but little is known about amygdala dysfunction in chronically irritable youth. We compared neural activation in SMD (n = 19), BD (n = 19), and healthy volunteer (HV; n = 15) youths during an implicit face-emotion processing task with angry, fearful and neutral expressions. In the right amygdala, both SMD and BD exhibited greater activity across all expressions than HV. However, SMD and BD differed from each other and HV in posterior cingulate cortex, posterior insula, and inferior parietal lobe. In these regions, only SMD showed deactivation in response to fearful expressions, whereas only BD showed deactivation in response to angry expressions. Thus, during implicit face emotion processing, youth with BD and those with SMD exhibit similar amygdala dysfunction but different abnormalities in regions involved in information monitoring and integration.

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Youths with severe mood dysregulation (SMD), bipolar disorder (BD), controls.

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Implicit face-emotion processing fMRI task with angry, fearful, neutral emotions.

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In R amygdala, SMD and BD had greater activity across all expressions vs controls.

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In whole brain analysis SMD had decreased, BD increased activity vs. other groups.