Pediatric Irritability: A Systems Neuroscience Approach

Is irritability multidimensional: Psychometrics of The Irritability and Dysregulation of Emotion Scale (TIDES-13)

Irritability is a common, impairing, and potentially multifaceted manifestation of psychopathology. We designed The Irritability and Dysregulation of Emotion Scale (TIDES-13) to determine whether various expressions of irritability in children and youth form multiple subdimensions with distinct correlates. We administered parent-report (n = 3875, mean age = 8.9) and youth self-report (n = 579, mean age = 15.1) versions of TIDES-13 in a population and community-based sample. We conducted exploratory/confirmatory factor analyses and regression analyses to examine the dimensionality of TIDES-13 and the associations of the scale with age, gender, anxiety, depression, ODD, ADHD traits, and the Affective Reactivity Index (ARI). A higher-order model with a global irritability dimension and four subdimensions, including proneness to anger (PA), internalized negative emotional reactivity (iNER), externalized negative emotional reactivity (eNER), and reactive aggression (RA), showed good to excellent fit in both parent-report and self-report. The global irritability dimension showed excellent internal reliability (⍵Total; parent-report = 0.97, ⍵Total; self-report = 0.95), explained a majority of the item variance (⍵Hierarchical; parent-report = 0.94, ⍵Hierarchical; self-report = 0.90), and was moderately correlated with the ARI (rparent = 0.68, rself = 0.77). Subdimensions PA, eNER, and RA were negatively associated with age in males, whereas iNER was positively associated with age in females. Traits of ODD and ADHD were associated primarily with the global irritability dimension, whereas iNER was strongly associated with anxiety and depression traits over and above the global irritability dimension. Our results support a unidimensional interpretation of irritability in a population sample. However, limited evidence of specific behavioral, age, and sex correlates with particular irritability subdimensions may warrant further investigation.

Oxytocin treatment rescues irritability-like behavior in Cc2d1a conditional knockout mice

Irritability, a state of excessive reactivity to negative emotional stimuli, is common in individuals with autism spectrum disorder (ASD). Although it has a significant negative impact of patients' disease severity and quality of life, the neural mechanisms underlying irritability in ASD remain largely unclear. We have previously demonstrated that male mice lacking the Coiled-coil and C2 domain containing 1a (Cc2d1a) in forebrain excitatory neurons recapitulate numerous ASD-like behavioral phenotypes, including impaired social behaviors and pronounced repetitive behaviors. Here, using the bottle-brush test (BBT) to trigger and evaluate aggressive and defensive responses, we show that Cc2d1a deletion increases irritability-like behavior in male but not female mice, which is correlated with reduced number of oxytocin (OXT)-expressing neurons in the paraventricular nucleus (PVN) of the hypothalamus. Intranasal OXT administration or chemogenetic activation of OXT neurons in the PVN rescues irritability-like behavior in Cc2d1a conditional knockout (cKO) mice. Administration of a selective melanocortin receptor 4 agonist, RO27-3225, which potentiates endogenous OXT release, also alleviates irritability-like behavior in Cc2d1a cKO mice, an effect blocked by a specific OXT receptor antagonist, L-368,899. We additionally identify a projection connecting the posterior ventral segment of the medial amygdala (MeApv) and ventromedial nucleus of the ventromedial hypothalamus (VMHvl) for governing irritability-like behavior during the BBT. Chemogenetic suppression of the MeApv-VMHvl pathway alleviates irritability-like behavior in Cc2d1a cKO mice. Together, our study uncovers dysregulation of OXT system in irritability-like behavior in Cc2d1a cKO mice during the BBT and provide translatable insights into the development of OXT-based therapeutics for clinical interventions.

Early Predictors and Concurrent Correlates of Tonic and Phasic Irritability in Adolescence

Irritability is a common presenting problem in youth mental health settings that is thought to include two components: tonic (e.g., irritable, touchy mood) and phasic (e.g., temper outbursts), each with unique correlates and outcomes, including later internalizing and externalizing problems, respectively. However, we are unaware of any studies of early predictors of tonic and phasic irritability. We utilized data from a longitudinal study of a community sample of 3-year-old children followed to age 15 (n = 444). We conducted confirmatory factor analysis (CFA) of items from several self-report irritability measures at age 15, including the Affective Reactivity Index, the International Personality Item Pool, the Schedule for Non-Adaptive and Adaptive Personality Youth Version, and the Child Depression Inventory, and examined their early childhood predictors. The CFA identified dimensions consistent with tonic and phasic irritability. Tonic irritability at age 15 was uniquely associated with concurrent internalizing disorders and suicidal behavior while phasic irritability was uniquely associated with concurrent externalizing disorders. When adolescent tonic and phasic irritability were examined together, female sex and parental depressive and substance use disorders at age 3 uniquely predicted adolescent tonic irritability. Additionally, male sex, less parental education, greater laboratory-observed anger and impulsivity, ODD symptoms, higher irritability, and no parental substance use history at age 3 uniquely predicted adolescent phasic irritability. Youth-reported tonic and phasic irritability at age 15 appear to be distinguishable constructs with distinct concurrent correlates and early antecedents. Findings have important implications for research on the etiology of irritability and developing effective treatments.

A network approach to the investigation of childhood irritability: probing frustration using social stimuli

BACKGROUND

Self-regulation in early childhood develops within a social context. Variations in such development can be attributed to inter-individual behavioral differences, which can be captured both as facets of temperament and across a normal:abnormal dimensional spectrum. With increasing emphasis on irritability as a robust early-life transdiagnostic indicator of broad psychopathological risk, linkage to neural mechanisms is imperative. Currently, there is inconsistency in the identification of neural circuits that underlie irritability in children, especially in social contexts. This study aimed to address this gap by utilizing a functional magnetic resonance imaging (fMRI) paradigm to investigate pediatric anger/frustration using social stimuli.

METHODS

Seventy-three children (M = 6 years, SD = 0.565) were recruited from a larger longitudinal study on irritability development. Caregivers completed questionnaires assessing irritable temperament and clinical symptoms of irritability. Children participated in a frustration task during fMRI scanning that was designed to induce frustration through loss of a desired prize to an animated character. Data were analyzed using both general linear modeling (GLM) and independent components analysis (ICA) and examined from the temperament and clinical perspectives.

RESULTS

ICA results uncovered an overarching network structure above and beyond what was revealed by traditional GLM analyses. Results showed that greater temperamental irritability was associated with significantly diminished spatial extent of activation and low-frequency power in a network comprised of the posterior superior temporal sulcus (pSTS) and the precuneus (p < .05, FDR-corrected). However, greater severity along the spectrum of clinical expression of irritability was associated with significantly increased extent and intensity of spatial activation as well as low- and high-frequency neural signal power in the right caudate (p < .05, FDR-corrected).

CONCLUSIONS

Our findings point to specific neural circuitry underlying pediatric irritability in the context of frustration using social stimuli. Results suggest that a deliberate focus on the construction of network-based neurodevelopmental profiles and social interaction along the normal:abnormal irritability spectrum is warranted to further identify comprehensive transdiagnostic substrates of the irritability.

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.

An investigation of the neural basis of anger attributions in irritable youth

Neurocognitive models of pediatric irritability suggest a prominent role of anger; however, few studies have investigated anger-related biases and their neural correlates. Resting state functional connectivity (rsFC) of the amygdala was examined in relation to anger attribution bias (AAB) in a sample of young children (5-9 years old; N = 60; 55% White, 26.7% Hispanic) with clinically significant irritability characterized by impairing emotional outbursts (IEOs). Children completed a resting state functional magnetic resonance imaging scan as well as the assessment of children's emotional skills (ACES), which yields three measures of AAB in the context of social situations, social behaviors, and facial expressions. ACES scores were entered into a general linear model to examine associations with rsFC of the bilateral amygdalae. Children with IEOs exhibited significant biases in attributing anger to others across all three ACES domains. Greater biases toward attributing anger in social situations were associated with reduced rsFC of the bilateral amygdalae with the fusiform/lingual gyri and lateral occipital cortex. Alternatively, greater biases toward attributing anger to facial expressions positively predicted right amygdala-precuneus rsFC. Greater bias toward attributing anger to others based on their behaviors was associated with heightened rsFC of the right amygdala with the left middle frontal gyrus. Findings extend previous work implicating functional connections among regions of default mode and frontoparietal networks in pediatric irritability. Longitudinal studies are needed to further investigate the putative role of AAB in the etiology and long-term outcomes of pediatric irritability. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

An Expanded Conceptual Framework for Understanding Irritability in Childhood: The Role of Cognitive Control Processes

Children prone to irritability experience significant functional impairments and internalising and externalising problems. Contemporary models have sought to elucidate the underlying mechanisms in irritability, such as aberrant threat and reward biases to improve interventions. However, the cognitive control processes that underlie threat (e.g., attention towards threats) and reward (e.g., attention towards reward-related cues) biases and the factors which influence the differential activation of positive and negative valence systems and thus leading to maladaptive activation of cognitive control processes (i.e., proactive and reactive control) are unclear. Thus, we aim to integrate extant theoretical and empirical research to elucidate the cognitive control processes underlying threat and reward processing that contribute to irritability in middle childhood and provide a guiding framework for future research and treatment. We propose an expanded conceptual framework of irritability that includes broad intraindividual and environmental vulnerability factors and propose proximal 'setting' factors that activate the negative valence and positive valence systems and proactive and reactive cognitive control processes which underpin the expression and progression of irritability. We consider the implications of this expanded conceptualisation of irritability and provide suggestions for future research.

Problems most concerning to parents of children with ADHD and emotional dysregulation in a randomized controlled trial of multinutrients: MADDY secondary analysis

OBJECTIVE

With dual focus on structured, objective quantification of parent observations of child's behavior and identifying behaviors most amenable to change, this report examines Parent Target Problems (PTP) as a secondary outcome in a randomized clinical trial (RCT) of children with attention-deficit/ hyperactivity disorder (ADHD) in which one primary outcome, Clinical Global Impression-Improvement, showed a significant advantage of multinutrients over placebo and the other, Likert-type parent ratings, showed significant improvement in both groups, without significant difference between them.

METHOD

In a multisite 8-week RCT of broad-spectrum micronutrients ("multinutrients"), parents of children ages 6-12 (N = 126, 73% male, 88% white) with ADHD and emotional dysregulation nominated their child's most concerning problem(s) at baseline and quantified them by frequency, duration, impairment, and consequences. At subsequent visits, parents re-quantified the problem(s). Blinded child psychiatrists independently reviewed the PTPs and rated change at two timepoints compared to baseline. PTPs were grouped into 9 categories. Mean ratings were compared between active and placebo groups and explored by category.

RESULTS

By week 8, a significant separation favored multinutrients: 38% of the multinutrient group were "definitely improved" or better, compared to 25% of the placebo group, and ratings of "no change" or "worse" occurred in 35% with placebo versus 23% with multinutrients (p = 0.04). Inattention (72.2%) and emotional dysregulation (69.1%) were the most frequently reported PTP categories. Inattention and internalizing symptoms improved more with multinutrients than placebo (p = 0.01, d = 0.55; p = 0.03, d = 0.80, respectively). The multinutrient advantage was not significant for 7 other symptoms, including hyperactivity/impulsivity, aggression, autistic symptoms, or emotional dysregulation/irritable oppositionality.

CONCLUSIONS

This secondary analysis found that the multinutrients, compared to placebo, were associated with improvements in parental concerns overall, and in two domains specifically: inattention and internalizing symptoms (anxiety/depression), but not in seven domains: hyperactivity/impulsivity, aggression, autistic symptoms or physiological symptoms, peer relationships or emotional dysregulation/irritable oppositionality.

Associations between trauma exposure and irritability within the family unit: a network approach

BACKGROUND

Pediatric irritability is a pervasive psychiatric symptom, yet its etiology remains elusive. While trauma exposure may contribute to the development of irritability, empirical research is limited. This study examined the prevalence of irritability among trauma-exposed children, identified factors that differentiate trauma-exposed children with and without irritability, and employed a network analysis to uncover associations between irritability and trauma exposure in the family unit.

METHODS

Sample included 676 children (56.3% male, mean age = 9.67 ± 3.7 years) and their parents referred by the Connecticut Department of Children and Families to Fathers for Change - a psychotherapy intervention designed to reduce intimate partner violence (IPV) and child maltreatment. Child's trauma exposure, post-traumatic stress disorder (PTSD) symptoms, and irritability were assessed pre-intervention using self- and caregiver-report. Parents self-reported their childhood and adulthood trauma exposures, PTSD symptoms, irritability, psychopathology, and IPV.

RESULTS

Across caregiver- and child-reports, 16%-17% of children exhibited irritability. Irritable children experienced greater trauma exposure, interpersonal violence, emotional abuse, and PTSD severity. They had caregivers, particularly mothers, with greater trauma histories, IPV, and psychopathology. Network analysis revealed 10 nodes directly correlated to child's irritability including child's PTSD severity, parental IPV (specifically psychological violence), and parental psychopathology.

CONCLUSIONS

Results provide initial empirical evidence that pediatric irritability is linked to trauma exposure, suggesting trauma histories be considered in the diagnosis and treatment of irritability. Interventions addressing caregiver trauma, IPV, and psychopathology may ameliorate pediatric irritability. Future studies could benefit from adopting network approaches with longitudinal or time series data to elucidate causality and points of intervention.

Irritability in Youths: A Critical Integrative Review

Irritability, defined as proneness to anger that may impair an individual's functioning, is common in youths. There has been a recent upsurge in relevant research. The authors combine systematic and narrative review approaches to integrate the latest clinical and translational findings and provide suggestions for addressing research gaps. Clinicians and researchers should assess irritability routinely, and specific assessment tools are now available. Informant effects are prominent, are stable, and vary by age and gender. The prevalence of irritability is particularly high among individuals with attention deficit hyperactivity disorder, autism spectrum disorder, and mood and anxiety disorders. Irritability is associated with impairment and suicidality risk independent of co-occurring diagnoses. Developmental trajectories of irritability (which may begin early in life) have been identified and are differentially associated with clinical outcomes. Youth irritability is associated with increased risk of anxiety, depression, behavioral problems, and suicidality later in life. Irritability is moderately heritable, and genetic associations differ based on age and comorbid illnesses. Parent management training is effective for treating psychological problems related to irritability, but its efficacy in treating irritability should be tested rigorously, as should novel mechanism-informed interventions (e.g., those targeting exposure to frustration). Associations between irritability and suicidality and the impact of cultural context are important, underresearched topics. Analyses of large, diverse longitudinal samples that extend into adulthood are needed. Data from both animal and human research indicate that aberrant responses to frustration and threat are central to the pathophysiology of irritability, revealing important translational opportunities.

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.

Neural Responses to Intranasal Oxytocin in Youths With Severe Irritability

OBJECTIVE

The authors investigated the neural impact of intranasal oxytocin on emotion processing areas in youths with severe irritability in the context of disruptive mood and behavior disorders.

METHODS

Fifty-two participants with severe irritability, as measured by a score ≥4 on the Affective Reactivity Index (ARI), with diagnoses of disruptive behavior disorders (DBDs) and/or disruptive mood dysregulation disorder (DMDD) were randomly assigned to treatment with intranasal oxytocin or placebo daily for 3 weeks. Assessments were conducted at baseline and at the end of the trial; the primary outcomes were measures of irritability on the ARI and ratings on the Clinical Global Impressions severity scale (CGI-S) focusing on DBD and DMDD symptoms, and secondary outcomes included the CGI improvement scale (CGI-I) and ratings of proactive and reactive aggressive behavior on the Reactive-Proactive Aggression Questionnaire. Forty-three participants (22 in the oxytocin group and 21 in the placebo group) completed pre- and posttreatment functional MRI (fMRI) scans with the affective Stroop task.

RESULTS

Youths who received oxytocin showed significant improvement in CGI-S and CGI-I ratings compared with those who received placebo. In the fMRI data, blood-oxygen-level-dependent (BOLD) responses to emotional stimuli in the dorsomedial prefrontal cortex and posterior cingulate cortex were significantly reduced after oxytocin compared with placebo. These BOLD response changes were correlated with improvement in clinical severity.

CONCLUSIONS

This study provides initial and preliminary evidence that intranasal oxytocin may induce neural-level changes in emotion processing in youths with irritability in the context of DBDs and DMDD. This may lead to symptom and severity changes in irritability.

Affective Contributions to Instrumental and Reactive Aggression in Middle Childhood: Variable- and Person-Centered Approaches

OBJECTIVE

Research on the role of affect in childhood aggression motives has largely focused on domain-level affective traits. Lower-order affective facets may show more distinct relationships with instrumental and reactive aggression - at both the variable and individual levels - and offer unique insights into whether and how several forms of affect are involved in aggression motives.

METHOD

Caregivers (98% mothers) of 342 children (Mage = 9.81 years, 182 girls, 31% White) reported on children's aggression and affect-relevant personality traits, personality pathology, and callous-unemotional traits.

RESULTS

Both reactive and instrumental aggressions were characterized by higher levels of trait irritability, fear, withdrawal, sadness, and callous-unemotional traits in zero-order analyses. Instrumental aggression was characterized by low trait positive emotions. Reactive aggression was uniquely associated with irritability, fear, withdrawal, and sadness, whereas instrumental aggression was uniquely associated with callous-unemotional traits and (low) positive emotions. Groups identified by latent profile analyses were differentiated only by aggression severity.

CONCLUSIONS

The findings support both the similarity and distinction of reactive and instrumental aggression vis-à-vis their affective phenomenology. Consistent with existing theories, reactive aggression was linked to multiple forms of negative emotionality, whereas instrumental aggression was linked to higher levels of callous-unemotional traits. In a novel finding, instrumental aggression was uniquely characterized by lower positive emotions. The findings highlight the utility of pre-registered approaches employing comprehensive personality-based affective frameworks to organize and understand similarities and differences between aggression functions.

Novel Assessment of the Impact of Irritability on Physiological and Psychological Frustration Responses in Adolescents

OBJECTIVE

Irritability, typically defined as a proneness to anger, particularly in response to frustration, falls at the intersection of emotion and disruptive behavior. Despite well-defined translational models, there are few convergent findings regarding the pathophysiology of irritability. Most studies utilize computer-based tasks to examine neural responses to frustration, with little work examining stress-related responding to frustration in social contexts. The present study is the first to utilize the novel Frustration Social Stressor for Adolescents (FSS-A) to examine associations between adolescent irritability and psychological and physiological responses to frustration.

METHOD

The FSS-A was completed by a predominantly male, racially, ethnically, and socioeconomically diverse sample of 64 12- to 17-year-olds, who were originally recruited as children with varying levels of irritability. Current irritability was assessed using the Multidimensional Assessment Profiles-Temper Loss scale (MAP-TL-Youth). Adolescents rated state anger and anxiety before and after the FSS-A, and usable salivary cortisol data were collected from 43 participants.

RESULTS

Higher MAP-TL-Youth scores were associated with greater increases in anger during the FSS-A, but not increases in anxiety, or alterations in cortisol. Pre-task state anger negatively predicted the slope of the rise in cortisol observed in anticipation of the FSS-A.

CONCLUSIONS

Results provide support for unique associations between adolescent irritability and anger during, and in anticipation of, frustrating social interactions. Such findings lay a foundation for future work aimed at informing physiological models and intervention targets.

A three-dimensional model of neural activity and phenomenal-behavioral patterns

How phenomenal experience and behavior are related to neural activity in physiology and psychopathology represents a fundamental question in neuroscience and psychiatry. The phenomenal-behavior patterns may be deconstructed into basic dimensions, i.e., psychomotricity, affectivity, and thought, which might have distinct neural correlates. This work provides a data overview on the relationship of these phenomenal-behavioral dimensions with brain activity across physiological and pathological conditions (including major depressive disorder, bipolar disorder, schizophrenia, attention-deficit/hyperactivity disorder, anxiety disorders, addictive disorders, Parkinson's disease, Tourette syndrome, Alzheimer's disease, and frontotemporal dementia). Accordingly, we propose a three-dimensional model of neural activity and phenomenal-behavioral patterns. In this model, neural activity is organized into distinct units in accordance with connectivity patterns and related input/output processing, manifesting in the different phenomenal-behavioral dimensions. (1) An external neural unit, which involves the sensorimotor circuit/brain's sensorimotor network and is connected with the external environment, processes external inputs/outputs, manifesting in the psychomotor dimension (processing of exteroception/somatomotor activity). External unit hyperactivity manifests in psychomotor excitation (hyperactivity/hyperkinesia/catatonia), while external unit hypoactivity manifests in psychomotor inhibition (retardation/hypokinesia/catatonia). (2) An internal neural unit, which involves the interoceptive-autonomic circuit/brain's salience network and is connected with the internal/body environment, processes internal inputs/outputs, manifesting in the affective dimension (processing of interoception/autonomic activity). Internal unit hyperactivity manifests in affective excitation (anxiety/dysphoria-euphoria/panic), while internal unit hypoactivity manifests in affective inhibition (anhedonia/apathy/depersonalization). (3) An associative neural unit, which involves the brain's associative areas/default-mode network and is connected with the external/internal units (but not with the environment), processes associative inputs/outputs, manifesting in the thought dimension (processing of ideas). Associative unit hyperactivity manifests in thought excitation (mind-wandering/repetitive thinking/psychosis), while associative unit hypoactivity manifests in thought inhibition (inattention/cognitive deficit/consciousness loss). Finally, these neural units interplay and dynamically combine into various neural states, resulting in the complex phenomenal experience and behavior across physiology and neuropsychiatric disorders.

Future Directions: The Phenomenology of Irritable Mood and Outbursts: Hang Together or Hang Separately1

Recognition of the importance of irritable mood and outbursts has been increasing over the past several decades. This "Future Directions" aims to develop a set of recommendations for future research emphasizing that irritable mood and outbursts "hang together," but have important distinctions and thus also need to "hang separately." Outbursts that are the outcome of irritable mood may be quite different from outbursts that are the trigger or driving force that make youth and his/her environment miserable. What, then, is the relation between irritable mood and outbursts? As the field currently stands, we not only cannot answer this question, but we may also lack the tools to effectively do so. Here, we will propose recommendations for understanding the phenomenology of irritable mood and outbursts so that more directed and clinically useful assessment tools can be designed. We discuss the transdiagnostic and treatment implications that relate to improvements in measurement. We describe the need to do more than repurpose our current assessment tools, specifically interviews and rating scales, which were designed for different purposes. The future directions of the study and treatment of irritable mood and outbursts will require, among others, using universally accepted nomenclature, supporting the development of tools to measure the characteristics of each irritable mood and outbursts, understanding the effects of question order, informant, development and longitudinal course, and studying the ways in which outbursts and irritable mood respond to treatment.

Systematic Review and Meta-Analysis: Early Irritability as a Transdiagnostic Neurodevelopmental Vulnerability to Later Mental Health Problems

OBJECTIVE

Irritability is a transdiagnostic indicator of child and adolescent internalizing and externalizing problems that is measurable from early life. The objective of this systematic review was to determine the strength of the association between irritability measured from 0 to 5 years and later internalizing and externalizing problems, to identify mediators and moderators of these relationships, and to explore whether the strength of the association varied according to irritability operationalization.

METHOD

Relevant studies published in peer-reviewed, English-language journals between the years 2000 and 2021 were sought from EMBASE, PsycINFO, MEDLINE, CINAHL, and ERIC. We synthesized studies that included a measure of irritability within the first 5 years of life and reported associations with later internalizing and/or externalizing problems. Methodological quality was assessed using the JBI-SUMARI Critical Appraisal Checklist.

RESULTS

Of 29,818 identified studies, 98 met inclusion criteria, with a total number of 932,229 participants. Meta-analysis was conducted on 70 studies (n = 831,913). Small, pooled associations were observed between infant irritability (0-12 months) and later internalizing (r = 0.14, 95% CI = 0.09, 0.20) and externalizing symptoms (r = 0.16, 95% CI = 0.11, 0.21) symptoms. For toddler/preschool irritability (13-60 months), small-to-moderate pooled associations were observed for internalizing (r = 0.21, 95% CI = 0.14, 0.28) and externalizing (r = 0.24, 95% CI = 0.18, 0.29) symptoms. These associations were not moderated by the lag between irritability and outcome assessment, although the strength of the associations varied according to irritability operationalization.

CONCLUSION

Early irritability is a consistent transdiagnostic predictor of internalizing and externalizing symptoms in childhood and adolescence. More work is required to understand how to accurately characterize irritability across this developmental period, and to understand mechanisms underlying the relationship between early irritability and later mental health problems.

DIVERSITY & INCLUSION STATEMENT

One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented racial and/or ethnic groups in science. One or more of the authors of this paper self-identifies as living with a disability. We actively worked to promote sex and gender balance in our author group. We actively worked to promote inclusion of historically underrepresented racial and/or ethnic groups in science in our author group.

STUDY PREREGISTRATION INFORMATION

Early irritability as a transdiagnostic neurodevelopmental vulnerability to early onset mental health problems: A systematic review; https://www.crd.york.ac.uk/prospero/; CRD42020214658.

Pharmacological and non-pharmacological interventions for irritability in autism spectrum disorder: a systematic review and meta-analysis with the GRADE assessment

BACKGROUND

Numerous interventions for irritability in autism spectrum disorder (ASD) have been investigated. We aimed to appraise the magnitude of pharmacological and non-pharmacological interventions for irritability in ASD without any restrictions in terms of eligible interventions.

METHODS

We systematically searched PubMed/MEDLINE, Scopus, and Web of Science until April 15, 2023. We included randomized controlled trials (RCTs) with a parallel design that examined the efficacy of interventions for the treatment of irritability in patients of any age with ASD without any restrictions in terms of eligible interventions. We performed a random-effects meta-analysis by pooling effect sizes as Hedges' g. We classified assessed interventions as follows: pharmacological monotherapy, risperidone plus adjuvant therapy versus risperidone monotherapy, non-pharmacological intervention, and dietary intervention. We utilized the Cochrane tool to evaluate the risk of bias in each study and the GRADE approach to assess the certainty of evidence for each meta-analyzed intervention.

RESULTS

Out of 5640 references, we identified 60 eligible articles with 45 different kinds of interventions, including 3531 participants, of which 80.9% were males (mean age [SD] = 8.79 [3.85]). For pharmacological monotherapy, risperidone (Hedges' g - 0.857, 95% CI - 1.263 to - 0.451, certainty of evidence: high) and aripiprazole (Hedges' g - 0.559, 95% CI - 0.767 to - 0.351, certainty of evidence: high) outperformed placebo. Among the non-pharmacological interventions, parent training (Hedges' g - 0.893, 95% CI - 1.184 to - 0.602, certainty of evidence: moderate) showed a significant result. None of the meta-analyzed interventions yielded significant effects among risperidone + adjuvant therapy and dietary supplementation. However, several novel molecules in augmentation to risperidone outperformed risperidone monotherapy, yet from one RCT each.

LIMITATIONS

First, various tools have been utilized to measure the irritability in ASD, which may contribute to the heterogeneity of the outcomes. Second, meta-analyses for each intervention included only a small number of studies and participants.

CONCLUSIONS

Only risperidone, aripiprazole among pharmacological interventions, and parent training among non-pharmacological interventions can be recommended for irritability in ASD. As an augmentation to risperidone, several novel treatments show promising effects, but further RCTs are needed to replicate findings. Trial registration PROSPERO, CRD42021243965.

A New Behavioral Paradigm for Frustrative Nonreward in Juvenile Mice

Background

Irritability, defined as proneness to anger, can reach a pathological extent. It is a defining symptom of disruptive mood dysregulation disorder and one of the most common reasons youths present for psychiatric evaluation and care. Aberrant responses to frustrative nonreward (FNR), the response to omission of expected reward, are central to the pathophysiology of irritability. FNR is a translational construct to study irritability across species. The development of preclinical FNR models would advance mechanistic studies of the important and relatively understudied clinical phenomenon of irritability.

Methods

We used FNR as a conceptual framework to develop a novel mouse behavioral paradigm named alternate poking reward omission. Juvenile mice were exposed to alternate poking reward omission and then examined with a battery of behavioral tests to determine the behavioral effect of FNR.

Results

FNR increased locomotion and aggression regardless of sex. These behavioral changes elicited by FNR resemble the symptoms observed in youth with severe irritability. FNR had no effect on anxiety-like, depression-like, or nonaggressive social behaviors.

Conclusions

Our alternate poking reward omission paradigm effectively elevated aggression and locomotion in juvenile mice. These frustration effects are directly related to behavioral symptoms of youth with severe irritability. Our novel behavioral paradigm lays the groundwork for further mechanistic studies of frustration and irritability in rodents.

Temporal dynamics of neurobehavioral hormone sensitivity in a scaled-down experimental model of early pregnancy and parturition

The hormonal changes of pregnancy and parturition can trigger robust changes in affective state, particularly among patients with a history of postpartum depression. However, more work is needed to elucidate the temporal dynamics of symptom emergence. The current study explored how quickly hormone-sensitive (HS+) individuals can be differentiated from hormone-insensitive (HS-) controls in the context of a tightly controlled experimental hormone manipulation, and which symptoms demonstrate the most rapid, consistent, and largest response during this protocol. Participants were female, non-pregnant, and euthymic, with a history of DSM-5 major depressive episode with peripartum onset (n = 15) or parous healthy controls with no psychiatric history (n = 15). Perinatal hormonal changes were simulated by inducing hypogonadism, adding back estradiol (E2) and progesterone (P4) to reach first-trimester levels for 8 weeks, and then subsequently withdrawing both hormones. Those reporting a 30% or greater increase during addback or withdrawal on select subscales of the Inventory of Depression and Anxiety Symptoms (IDAS) were identified as HS+. Participants provided daily ratings of symptoms throughout the study via the Daily Record of Severity of Problems. Results indicated that HS+ participants could be differentiated from HS- participants early in the hormone protocol, with many symptoms showing significantly greater change from baseline within the first week of addback. Notably, the most rapid symptom increases were observed for Anger/Irritability, Mood Swings, Overwhelm, Lethargy, Increased Appetite, Joint and Muscle Pain, and Breast Tenderness, reaching 50% of peak group contrast within the first week of hormone addback. The largest group effects were observed for Anger/Irritability, followed by Fatigue and Anxiety, and the most consistent group effects were observed for Anger/Irritability, Interpersonal Conflict, Overwhelm, and Hopelessness. Findings support the role of reproductive hormones in the onset of perinatal affective disorders. The rapid emergence of anger and irritability in HS+ participants suggests that these symptoms may be early indicators of perinatal hormone sensitivity.

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.

Irritability: A concept analysis

Irritability is a term used to describe feelings of anger, annoyance and impatience, and is commonly experienced by individuals in daily life. However, there are diverse conceptualizations of irritability in public and clinical research, which often result in confusing irritability with anger and other overlapping concepts. This, in turn, leads to a lack of conceptual clarity. Accordingly, the purpose of this concept analysis was to explore the irritability concept, including its definitions, defining characteristics, antecedents, consequences and empirical referents. The findings showed that irritability is predominantly conceptualized as a psychophysiological concept in the literature. We demonstrated that irritability can be differentiated from overlapping concepts like anger by qualities, such as 'unpredictability and lowered emotion control', 'lowered threshold for negative emotional stimuli', 'being manifested in response to frustrative situations or physiological needs' and 'experience of disproportionate and unjustified emotional irritation'. Importantly, severe irritability prospectively predicts psychiatric disorders and greater impairments in health, financial, educational and social functioning in individuals. Taken together, our analysis showed that one should take into account the context, duration, intensity and importantly outcomes, when assessing irritability in an individual. Considering these findings and the presence of irritability in nursing practice, it is crucial for nurses to recognize and successfully identify this concept in the nursing care they provide within the diverse settings and patient populations.

Categorical and dimensional approaches to the developmental relationship between ADHD and irritability

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) and irritability commonly co-occur, and follow similar developmental trajectories from childhood to adolescence. Understanding of the developmental relationship between these co-occurrences is limited. This study provides a longitudinal assessment of how ADHD diagnostic status and symptom patterns predict change in irritability.

METHODS

A community sample of 337 participants (45.2% ADHD), recruited for the Childhood Attention Project, completed the Affective Reactivity Index (ARI) to measure irritability at baseline (mean age 10.5 years) and follow-up after 18-months. Latent change score models were used to assess how (a) baseline ADHD vs. control group status, (b) baseline symptom domain (inattention, hyperactivity-impulsivity) and (c) longitudinal change in ADHD symptom severity predicted change in irritability.

RESULTS

Irritability was significantly higher among the ADHD group than controls; however, change in irritability over time did not differ between groups. When assessed across the entire cohort, change in irritability was predicted by higher symptom count in the hyperactive-impulsive domain, but not the inattentive domain. Greater declines in ADHD symptoms over time significantly predicted greater declines in irritability. Baseline ADHD symptom severity was found to significantly predict change in irritability; however, baseline irritability did not significantly predict change in ADHD symptoms.

CONCLUSIONS

ADHD symptoms-particularly hyperactive-impulsive symptoms-predict the degree and trajectory of irritability during childhood and adolescence, even when symptoms are below diagnostic thresholds. The use of longitudinal, dimensional and symptom domain-specific measures provides additional insight into this relationship.

Future Directions in Youth Irritability Research

Research on irritability in children and adolescents has proliferated over the last 20 years. The evidence shows the clinical and developmental significance of irritable mood and behavior in youth, and it has led to significant changes in mental health classification, diagnosis, and services. At the same time, this research (including our own) has led to relatively little new in terms of practical, empirically based guidance to improve interventions and outcomes. In this article, we briefly summarize some of these developments and current evidence-based practices. We then put forth two key substantive challenges (the "whats") for future research to address: (a) the need for more effective treatments, especially evaluating and adapting evidence-based treatments that are already well-established for problems related to irritability (e.g., cognitive-behavioral therapies for internalizing and externalizing problems); and (b) the need for a better mechanistic understanding of irritability's phenomenology (e.g., phasic vs. tonic irritability, how frustration unfolds) and putative underlying mechanisms (e.g., cognitive control, threat and reward dysfunction). Lastly, we suggest three methodological approaches (the "hows") that may expedite progress in such areas: (a) ecological momentary assessment, (b) digital health applications, and (c) leveraging existing datasets. We hope this article will be useful for students and early-career researchers interested in tackling some of these important questions to better meet the needs of severely irritable youth.

Associations between childhood irritability and neural reactivity to maternal feedback in adolescence

Early irritability, a transdiagnostic vulnerability for psychopathology, is associated with alterations in neural reactivity to emotional stimuli and reward; however, associations between childhood irritability and neural markers of risk may be mitigated by the quality of caregiving youth receive. We examined longitudinal relationships between irritability in childhood and young adolescents' neural activity of regions typically associated with emotion regulation and reward processing during processing of maternal feedback and tested whether these associations were moderated by youth's perceptions of the parent-child relationship quality. Eighty-one adolescents (Mage = 11.1 years) listened to maternal critical and praising feedback while undergoing functional magnetic resonance imaging. Age 3 irritability, assessed observationally, was negatively associated with age 11 neural reactivity to maternal criticism in a cluster in the right dorsolateral prefrontal cortex (dlPFC), particularly for youths who reported more positive maternal parenting. Given the role of the dlPFC activation in the effortful processing of emotional stimuli, decreased activation may reflect disengagement from negatively valenced interpersonal feedback in the context of a positive caregiving environment, thereby mitigating psychopathology risk associated with irritability.

Is the distinction between tonic and phasic irritability meaningful in 3-year-old children?

Irritability encompasses both normative misbehavior in early childhood and clinically significant problems across development. Recent studies have distinguished between tonic (i.e., persistently angry or grumpy mood) and phasic (i.e., temper tantrums or outbursts) forms of irritability and shown that they have different implications for psychopathology and functioning. However, data on this distinction in young (i.e., preschool aged) children are nonexistent. We utilized data from a longitudinal study of a community sample of 462 3-year-olds followed to age 15. We conducted confirmatory factor analysis (CFA) using items from a diagnostic interview and several parent-report inventories and examined concurrent and prospective associations with clinically relevant variables. The CFA identified dimensions consistent with tonic and phasic irritability. Tonic irritability was independently associated with concurrent parent-reported temperamental negative affectivity and surgency, and depressive and oppositional defiant (ODD) disorders, and predicted higher rates of disruptive behavior disorders (DBD) and suicidal behavior in later childhood and adolescence. Phasic irritability was independently associated with concurrent laboratory observations of child impulsivity, parent-reported temperamental negative affectivity, surgency, and low effortful control, maladaptive parenting, and generalized anxiety disorder (GAD), attention-deficit hyperactivity disorder (ADHD), and ODD, but it did not predict later psychopathology. Tonic and phasic irritability are separable in 3-year-old children, but their correlates and outcomes are not as distinct as in older youth. This may reflect the greater difficulty characterizing normative and pathological irritability in the preschool period.

Intranasal Oxytocin in Pediatric Populations: Exploring the Potential for Reducing Irritability and Modulating Neural Responses: A Mini Review

Endogenous neuropeptide Oxytocin (OXT) plays a crucial role in modulating pro-social behavior and the neural response to social/emotional stimuli. Intranasal administration is the most common method of delivering OXT. Intranasal OXT has been implemented in clinical studies of various psychiatric disorders with mixed results, mainly related to lack of solid pharmacodynamics and pharmacokinetics model. Due to intranasal OXT's mechanism of reducing the activation of neural areas implicated in emotional responding and emotion regulation, a psychopathology with this target mechanism could be potentially excellent candidate for future clinical trial. In this regard, irritability in youth may be a very promising target for clinical studies of intranasal OXT. Here we provide a mini-review of fifteen randomized controlled trials in pediatric patients with diagnoses of autism spectrum disorder (ASD), Prader-Willi syndrome (PWS), or Phelan-McDermid syndrome (PMS). Most studies had small sample sizes and varying dosages, with changes in irritability, mainly as adverse events (AEs). Neuroimaging results showed modulation of the reward processing system and the neural areas implicated in social-emotional information processing by intranasal OXT administration. Further research is needed to determine the most effective dose and duration of OXT treatment, carefully select target psychopathologies, verify target engagement, and measure adverse event profiles.

Network analysis of ecological momentary assessment identifies frustration as a central node in irritability

BACKGROUND

Irritability presents transdiagnostically, commonly occurring with anxiety and other mood symptoms. However, little is known about the temporal and dynamic interplay among irritability-related clinical phenomena. Using a novel network analytic approach with smartphone-based ecological momentary assessment (EMA), we examined how irritability and other anxiety and mood symptoms were connected.

METHODS

Sample included 152 youth ages 8-18 years (M ± SD = 12.28 ± 2.53; 69.74% male; 65.79% White) across several diagnostic groups enriched for irritability including disruptive mood dysregulation disorder (n = 34), oppositional defiant disorder (n = 9), attention-deficit/hyperactivity disorder (n = 47), anxiety disorder (n = 29), and healthy comparisons (n = 33). Participants completed EMA on irritability-related constructs and other mood and anxiety symptoms three times a day for 7 days. EMA probed symptoms on two timescales: "since the last prompt" (between-prompt) versus "at the time of the prompt" (momentary). Irritability was also assessed using parent-, child- and clinician-reports (Affective Reactivity Index; ARI), following EMA. Multilevel vector autoregressive (mlVAR) models estimated a temporal, a contemporaneous within-subject and a between-subject network of symptoms, separately for between-prompt and momentary symptoms.

RESULTS

For between-prompt symptoms, frustration emerged as the most central node in both within- and between-subject networks and predicted more mood changes at the next timepoint in the temporal network. For momentary symptoms, sadness and anger emerged as the most central node in the within- and between-subject network, respectively. While anger was positively related to sadness within individuals and measurement occasions, anger was more broadly positively related to sadness, mood lability, and worry between/across individuals. Finally, mean levels, not variability, of EMA-indexed irritability were strongly related to ARI scores.

CONCLUSIONS

This study advances current understanding of symptom-level and temporal dynamics of irritability. Results suggest frustration as a potential clinically relevant treatment target. Future experimental work and clinical trials that systematically manipulate irritability-related features (e.g. frustration, unfairness) will elucidate the causal relations among clinical variables.

A New Behavioral Paradigm for Frustrative Non-reward Reveals a Global Change in Brain Networks by Frustration

Background

Irritability, defined as proneness to anger, can reach a pathological extent. It is a defining symptom of Disruptive Mood Dysregulation Disorder (DMDD) and one of the most common reasons youth presents for psychiatric evaluation and care. Aberrant responses to frustrative non-reward (FNR, the response to omission of expected reward) are central to the pathophysiology of irritability. FNR is a translational construct to study irritability across species. The development of preclinical FNR models would advance mechanistic studies of the important and relatively understudied clinical phenomenon of irritability.

Methods

We used FNR as a conceptual framework to develop a novel mouse behavioral paradigm named Alternate Poking Reward Omission (APRO). After APRO, mice were examined with a battery of behavioral tests and processed for whole brain c-Fos imaging. FNR increases locomotion and aggression in mice regardless of sex. These behavioral changes resemble the symptoms observed in youth with severe irritability. There is no change in anxiety-like, depression-like, or non-aggressive social behaviors. FNR increases c-Fos+ neurons in 13 subregions of thalamus, iso-cortex and hippocampus including the prelimbic, ACC, hippocampus, dorsal thalamus, cuneiform nucleus, pons, and pallidum areas. FNR also shifts the brain network towards a more global processing mode.

Conclusion

Our novel FNR paradigm produces a frustration effect and alters brain processing in ways resembling the symptoms and brain network reconfiguration observed in youth with severe irritability. The novel behavioral paradigm and identified brain regions lay the groundwork for further mechanistic studies of frustration and irritability in rodents.

Behavioral self-regulation in pediatric bipolar disorder and healthy offspring of bipolar patients

OBJECTIVES

This study investigated behavioral self-regulation problems using the Children's Hostility Inventory (CHI) in pediatric bipolar disorder (PBD), healthy offspring of bipolar disorder patients (HOBD), and healthy controls (HC) without previous history of psychiatric disorders.

METHODS

The CHI was administered to 41 consecutive children and adolescents diagnosed with PBD, to 16 HOBD, and to 22 HC. The inventory assessed irritability, expression, hostility, and aggression and was completed by the children with the help of their mothers. Adolescents and their respective parents were interviewed separately using the Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present and Lifetime Version (K-SADS-PL).

RESULTS

All subscales of the CHI presented statistically significant differences, except for the subscale assessing feelings of suspicion. Pairwise comparisons revealed consistently significant differences between the PBD group and controls, indicating more self-regulation difficulties in the PBD group, represented by high levels of hostility and aggressive behavior. There were no significant differences between the PBD and HOBD groups.

CONCLUSIONS

Future studies should further investigate if such behavior is state-dependent or a trait of bipolar juvenile expression. Expression of hostility and irritability should be considered relevant targets in psychosocial approaches addressing this population.

Neural correlates of peer evaluation in irritable adolescents: Linking anticipation to receipt of social feedback

Elevated irritability during adolescence predicts mental health issues in adulthood. Social interactions commonly elicit symptoms of irritability. Prior research has traditionally examined neural activity during the anticipation of, and immediate reaction to, social feedback separately in irritable adolescents. However, studies suggest that irritable adolescents demonstrate altered brain activation when anticipating feedback, and these alterations may have downstream effects on the neural activity when actually presented with feedback. Thus, the goal of this study was to characterize the influence of irritability on the relationship between brain function during anticipation and receipt of social feedback. We leveraged the Virtual School task to mimic social interactions using dynamic stimuli. Parallel region of interest (ROI) analyses tested effects of anticipatory bilateral amygdala (or dorsal anterior cingulate cortex; dACC) activation on the dACC (or bilateral amygdala) activation during receipt of peer feedback. Parallel exploratory whole-brain analyses were conducted to identify the effects of anticipatory bilateral amygdala or dACC activation on other regions during receipt of peer feedback. In ROI analyses, more vs. less irritable adolescents showed distinct relationships between anticipatory bilateral amygdala activation and dACC activation when receiving predictably mean feedback. Across both whole-brain analyses, anticipatory bilateral amygdala and dACC activation were separately associated with activation in socioemotional regions of the brain during subsequent feedback. These relationships were modulated by irritability, and the valence and predictability of the feedback. This suggests that irritable adolescents may engage in altered emotion processing and regulation strategies, depending on the valence and predictability of social feedback.

Dysfunction in differential reward-punishment responsiveness in conduct disorder relates to severity of callous-unemotional traits but not irritability

BACKGROUND

Conduct disorder (CD) has been associated with dysfunction in reinforcement-based decision-making. Two forms of affective traits that reflect the components of CD severity are callous-unemotional (CU; reduced guilt/empathy) traits and irritability. The form of the reinforcement-based decision-making dysfunction with respect to CD and CU traits remains debated and has not been examined with respect to irritability in cases with CD. The goals of the current study were to determine the extent of dysfunction in differential (reward v. punishment) responsiveness in CD, and CU traits and irritability in participants with CD.

METHODS

The study involved 178 adolescents [typically developing (TD; N = 77) and cases with CD (N = 101)]. Participants were scanned with fMRI during a passive avoidance task that required participants to learn to respond to (i.e. approach) stimuli that engender reward and refrain from responding to (i.e. passively avoid) stimuli that engender punishment.

RESULTS

Adolescents with CD showed reduced differential reward-punishment responsiveness within the striatum relative to TD adolescents. CU traits, but not irritability, were associated with reduced differential reward-punishment responsiveness within the striatum, rostromedial, and lateral frontal cortices.

CONCLUSIONS

The results suggest CD is associated with reduced differential reward-punishment responsiveness and the extent of this dysfunction in participants with CD is associated with the severity of CU traits but not irritability.

Neural bases of frustration-aggression theory: A multi-domain meta-analysis of functional neuroimaging studies

BACKGROUND

Early evidence suggests that unexpected non-reward may increase the risk for aggressive behaviors. Despite the growing interest in understanding brain functions that may be implicated in aggressive behaviors, the neural processes underlying such frustrative events remain largely unknown. Furthermore, meta-analytic results have produced discrepant results, potentially due to substantial differences in the definition of anger/aggression constructs.

METHODS

Therefore, we conducted a coordinate-based meta-analysis, using the activation likelihood estimation algorithm, on neuroimaging studies examining reward omission and retaliatory behaviors in healthy subjects. Conjunction analyses were further examined to discover overlapping brain activations across these meta-analytic maps.

RESULTS

Frustrative non-reward deactivated the orbitofrontal cortex, ventral striatum and posterior cingulate cortex, whereas increased activations were observed in midcingulo-insular regions. Retaliatory behaviors recruited the left fronto-insular and anterior midcingulate cortices, the dorsal caudate and the primary somatosensory cortex. Conjunction analyses revealed that both strongly activated midcingulo-insular regions.

LIMITATIONS

Spatial overlap between neural correlates of frustration and retaliatory behaviors was conducted using a conjunction analysis. Therefore, neurobiological markers underlying the temporal sequence of the frustration-aggression theory should be interpreted with caution.

CONCLUSIONS

Nonetheless, our results underscore the role of anterior midcingulate/pre-supplementary motor area and fronto-insular cortex in both frustration and retaliatory behaviors. A neurobiological framework for understanding frustration-based impulsive aggression is provided.

Editorial: Early Crying in Infancy: An Indicator of Emotional, Behavioral, and Neurobiological Outcomes in Childhood

Psychiatric disorders contribute to substantial morbidity and mortality among young people. While the majority of clinical diagnoses are still being made in adolescence and young adulthood,¹ underlying susceptibility or vulnerability factors are increasingly being recognized in early life-some as early as infancy. Identifying such factors in children in early stages of development offers an opportunity to intervene and potentially prevent later development of psychiatric disorders. Further, leveraging neuroimaging data associated with early developmental trajectories will improve our understanding of the complex interplay between neurobiological variation and psychiatric morbidity.

Tonic and phasic irritability in 6-year-old children: differential correlates and outcomes

OBJECTIVE

Irritability is a common and clinically important problem in children and adolescents and a risk factor for later psychopathology and impairment. Irritability can manifest in both tonic (e.g., irritable, touchy mood) and phasic (e.g., temper outburst) forms, and recent studies of adolescents suggest that they predict different outcomes. However, no studies have examined whether tonic and phasic irritability are empirically distinguishable in 6-year-old children and whether they have distinct correlates and outcomes.

METHOD

We utilized data from a longitudinal study of an unselected community sample of four hundred fifty-two 6-year-olds followed at 3-year intervals to age 15. We conducted confirmatory factor analysis (CFA) using relevant items from a diagnostic interview and several parent-report inventories.

RESULTS

The CFA identified dimensions that were consistent with tonic and phasic irritability. Tonic irritability was independently associated with concurrent parent-reported temperamental negative affectivity and internalizing and externalizing disorders at age 6 and predicted higher rates of internalizing psychopathology, and suicidal ideation, in adolescence. Phasic irritability was independently associated with concurrent parent-reported temperamental negative affectivity, surgency, and low effortful control, maladaptive parenting styles and practices, and externalizing disorders at age 6, and predicted higher rates of externalizing psychopathology in adolescence.

CONCLUSIONS

Tonic and phasic irritability in 6-year-old children appear to be distinguishable constructs with different temperament and parenting correlates and psychopathological outcomes. Distinguishing these components has implications for research on the etiology and pathophysiology of irritability and developing effective treatments.

Narrative Review: Impairing Emotional Outbursts: What They Are and What We Should Do About Them

OBJECTIVE

Impairing emotional outbursts, defined by extreme anger or distress in response to relatively ordinary frustrations and disappointments, impact all mental health care systems, emergency departments, schools, and juvenile justice programs. However, the prevalence, outcome, and impact of outbursts are difficult to quantify because they are transdiagnostic and not explicitly defined by current diagnostic nosology. Research variably addresses outbursts under the rubrics of tantrums, anger, irritability, aggression, rage attacks, or emotional and behavioral dysregulation. Consistent methods for identifying and assessing impairing emotional outbursts across development or systems of care are lacking.

METHOD

The American Academy of Child and Adolescent Psychiatry Presidential Task Force (2019-2021) conducted a narrative review addressing impairing emotional outbursts within the limitations of the existing literature and independent of diagnosis.

RESULTS

Extrapolating from the existing literature, best estimates suggest that outbursts occur in 4%-10% of community children (preschoolers through adolescents). Impairing emotional outbursts may respond to successful treatment of the primary disorder, especially for some children with attention-deficit/hyperactivity disorder whose medications have been optimized. However, outbursts are generally multi-determined and often represent maladaptive or deficient coping strategies and responses.

CONCLUSION

Evidence-based strategies are necessary to address factors that trigger, reinforce, or excuse the behaviors and to enhance problem-solving skills. Currently available interventions yield only modest effect sizes for treatment effect. More specific definitions and measures are needed to track and quantify outbursts and to design and assess the effectiveness of interventions. Better treatments are clearly needed.

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.

Clarifying the role of Cortico-Cortical and Amygdalo-Cortical brain dysconnectivity associated with Conduct Problems

A recent meta-analysis of resting-state functional connectivity studies revealed that individuals exhibiting antisocial behaviors or conduct problems may show disrupted brain connectivity in networks underpinning socio-affective and attentional processes. However, studies included in the meta-analysis generally rely on small sample sizes and substantially differ in terms of psychometric scales and neuroimaging methodologies. Therefore, we aimed to identify reliable functional brain connectivity alterations associated with severity of conduct problems using a large sample of adolescents and two measures of conduct problems. In a sample of 1416 children and adolescents, mass-univariate analyses of connectivity measures between 333 cortical parcels were conducted to examine the relationship between resting-state functional cortical-cortical connectome and the severity of conduct problems using the Child Behavior Checklist (CBCL) and the Strengths and Difficulties Questionnaire (SDQ). At a liberal threshold, results showed that the functional brain connectivity significantly associated with conduct problems largely differ between the two scales. Indeed, only 21 pairs of brain regions overlapped between the CBCL and SDQ. Permutation feature importance of these 21 brain connectivity measures revealed that connectivity between precentral/postcentral gyri and lateral prefrontal cortex (both ventral and dorsal) were the most important features in explaining variance in conduct problems. The current study highlights that psychometric measures may yield distinct functional connectivity results. Moreover, severity of conduct problems in children and adolescents was mainly associated with deficient functional connectivity of somatomotor and ventral attention networks indicating potential alterations in motor, cognitive and reward processes.

Irritability and its relationship with psychosocial symptoms and quality of life in adolescents with epilepsy receiving levetiracetam therapy: A case-control study

BACKGROUND

Levetiracetam, a widely used anticonvulsant drug in children and adolescents, has been associated with irritability, psychosocial symptoms, and low quality of life, which are also influenced by other epilepsy variables.

PURPOSE

The objective of this study was to investigate the level of treatment-related irritability in adolescents receiving levetiracetam, and to evaluate the relationship between irritability levels and psychosocial symptoms, and quality of life.

METHODS

A cross-sectional, case-control study was conducted. Consecutive adolescent patients with epilepsy aged 11-17 years with partial or generalized seizures, treated with either levetiracetam or valproic acid for at least 6 months, and healthy controls were recruited. The Affective Reactivity Index parent report and self-report, Strengths and Difficulties Questionnaire, and Pediatric Quality of Life Inventory-Psychosocial subscale were utilized to assess irritability, psychosocial symptoms, and functioning.

RESULTS

A total of 120 participants were analyzed; 33 patients in the LEV group, 45 patients in the VPA group, and 42 healthy controls. Both self and parent report irritability levels of the LEV group were found to be significantly higher than those of healthy controls. The irritability levels of the LEV and VPA groups were not statistically different, but still the LEV group had higher irritability levels on both scales. In the LEV group, irritability was positively correlated with behavioral, emotional, and attention/hyperactivity problems, and also negatively correlated with psychosocial quality of life.

CONCLUSION

Adolescents with epilepsy using LEV have a high level of irritability and this is associated with some psychosocial symptoms and poor quality of life.

Developmental patterning of irritability enhances prediction of psychopathology in preadolescence: Improving RDoC with developmental science

The transdiagnostic importance of irritability in psychopathology has been demonstrated. However, the contribution of developmentally unfolding irritability patterns to specific clinical and neural outcomes remains an important and unanswered question. To address this gap in the literature, irritability patterns of 110 youth from a large, diverse cohort were assessed at preschool age and again at early school age (∼2.5 years later) with a dimensional irritability scale designed to capture the normal:abnormal spectrum. At preadolescence (∼6 years later), clinical outcomes (internalizing/externalizing symptoms) derived from a semistructured clinical interview and neural outcomes (characterized as gray-matter-volume abnormalities) were assessed. For clinical outcomes, preschool-age irritability alone was a transdiagnostic predictor of internalizing and externalizing symptoms at preadolescence. However, in a model including both preschool and early school age, irritability provided greater specificity, suggesting that higher irritability at early school age related to elevated preadolescent externalizing but not internalizing symptoms. In terms of neural outcomes, elevated preschool irritability did not predict preadolescent gray-matter-volume abnormality; however, irritability at early school age demonstrated an interactive effect among regions, with reduced volume in preadolescence emotional regions (e.g., amygdala, medial orbitofrontal cortex) and increased volume in other regions (e.g., cerebellum). These complex patterns highlight the contribution of a developmentally informed approach, the National Institute of Mental Health's Research Domain Criteria (RDoC) approach, to yield transdiagnostic phenotypes and multiple units of analysis. Capturing these individual differences and developmental heterogeneity can provide critical insight into the unfolding of mechanisms underlying emerging psychopathology. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Convergent neural correlates of prenatal exposure to air pollution and behavioral phenotypes of risk for internalizing and externalizing problems: Potential biological and cognitive pathways

Humans are ubiquitously exposed to neurotoxicants in air pollution, causing increased risk for psychiatric outcomes. Effects of prenatal exposure to air pollution on early emerging behavioral phenotypes that increase risk of psychopathology remain understudied. We review animal models that represent analogues of human behavioral phenotypes that are risk markers for internalizing and externalizing problems (behavioral inhibition, behavioral exuberance, irritability), and identify commonalities among the neural mechanisms underlying these behavioral phenotypes and the neural targets of three types of air pollutants (polycyclic aromatic hydrocarbons, traffic-related air pollutants, fine particulate matter < 2.5 µm). We conclude that prenatal exposure to air pollutants increases risk for behavioral inhibition and irritability through distinct mechanisms, including altered dopaminergic signaling and hippocampal morphology, neuroinflammation, and decreased brain-derived neurotrophic factor expression. Future studies should investigate these effects in human longitudinal studies incorporating complex exposure measurement methods, neuroimaging, and behavioral characterization of temperament phenotypes and neurocognitive processing to facilitate efforts aimed at improving long-lasting developmental benefits for children, particularly those living in areas with high levels of exposure.

Differential associations of conduct disorder, callous-unemotional traits and irritability with outcome expectations and values regarding the consequences of aggression

BACKGROUND

Previous work has examined the association of aggression levels and callous-unemotional traits with outcome expectations and values regarding the consequences of aggression. Less work has examined the outcome expectations and values regarding the consequences of aggression of adolescents with Conduct Disorder (CD). Also, no studies have examined links between irritability (a second socio-affective trait associated with CD) and these social cognitive processes despite the core function of anger in retaliatory aggression and establishing dominance.

METHOD

The current study, investigating these issues, involved 193 adolescents (typically developing [TD; N = 106], 87 cases with CD [N = 87]). Participants completed an adaptation of the Outcomes Expectations and Values Questionnaire and were assessed for CU traits and irritability via the Inventory of Callous-Unemotional traits and the Affective Reactivity Index.

RESULTS

While CD was associated with atypical outcome expectations this was not seen within statistical models including CU traits and irritability. CU traits were associated with decreased expectation that aggression would result in feelings of remorse and victim suffering, as well as decreased concern that aggressive acts would result in punishment and victim suffering. Irritability was associated with increased expectations and concern that aggression would result in dominance and forced respect.

CONCLUSIONS

The results suggest that CU traits and irritability, often present in youth with CD, are associated with different forms of maladaptive outcome expectations and values regarding the consequences of aggression. This suggests that the atypical social cognitive processes underlying aggressive behavior among youth exhibiting CU traits may differ from those exhibiting problems regulating anger.

Associations of Irritability With Functional Connectivity of Amygdala and Nucleus Accumbens in Adolescents and Young Adults With ADHD

OBJECTIVE

Irritability is a common characteristic in ADHD. We examined whether dysfunction in neural connections supporting threat and reward processing was related to irritability in adolescents and young adults with ADHD.

METHOD

We used resting-state fMRI to assess connectivity of amygdala and nucleus accumbens seeds in those with ADHD (n = 34) and an age- and gender-matched typically-developing comparison group (n = 34).

RESULTS

In those with ADHD, irritability was associated with atypical functional connectivity of both seed regions. Amygdala seeds showed greater connectivity with right inferior frontal gyrus and caudate/putamen, and less connectivity with precuneus. Nucleus accumbens seeds showed altered connectivity with middle temporal gyrus and precuneus.

CONCLUSION

The irritability-ADHD presentation is associated with atypical functional connectivity of reward and threat processing regions with cognitive control and emotion processing regions. These patterns provide novel evidence for irritability-associated neural underpinnings in adolescents and young adults with ADHD. The findings suggest cognitive and behavioral treatments that address response to reward, including omission of an expected reward and irritability, may be beneficial for ADHD.

Prefrontal modulation of frustration-related physiology in preschool children ranging from low to severe irritability

Limbic-prefrontal connectivity during negative emotional challenges underpins a wide range of psychiatric disorders, yet the early development of this system is largely unknown due to difficulties imaging young children. Functional Near-Infrared Spectroscopy (fNIRS) has advanced an understanding of early emotion-related prefrontal activation and psychopathology, but cannot detect activation below the outer cortex. Galvanic skin response (GSR) is a sensitive index of autonomic arousal strongly influenced by numerous limbic structures. We recorded simultaneous lateral prefrontal cortex (lPFC) activation via fNIRS and GSR in 73 3- to 5-year-old children, who ranged from low to severe levels of irritability, during a frustration task. The goal of the study was to test how frustration-related PFC activation modulated psychophysiology in preschool children, and whether associations were moderated by irritability severity. Results showed lPFC activation significantly increased, and GSR levels significantly decreased, as children moved from frustration to rest, such that preschoolers with the highest activation had the steepest recovery. Further, this relation was moderated by irritability such that children with severe irritability showed no association between lPFC activation and GSR. Results suggest functional connections between prefrontal and autonomic nervous systems are in place early in life, with evidence of lPFC down-regulation of frustration-based stress that is altered in early psychopathology. Combining fNIRS and GSR may be a promising novel approach for inferring limbic-PFC processes that drive early emotion regulation and psychopathology.

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Low to high irritable preschoolers tolerated simultaneous fNIRS and GSR recording.

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Frustration-related lPFC activation predicted steeper GSR recovery.

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Irritability moderated the association between lPFC activation and GSR recovery.

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Preschoolers with high irritability showed no lPFC-GSR association.

Hypothalamic syndrome

Hypothalamic syndrome (HS) is a rare disorder caused by disease-related and/or treatment-related injury to the hypothalamus, most commonly associated with rare, non-cancerous parasellar masses, such as craniopharyngiomas, germ cell tumours, gliomas, cysts of Rathke's pouch and Langerhans cell histiocytosis, as well as with genetic neurodevelopmental syndromes, such as Prader-Willi syndrome and septo-optic dysplasia. HS is characterized by intractable weight gain associated with severe morbid obesity, multiple endocrine abnormalities and memory impairment, attention deficit and reduced impulse control as well as increased risk of cardiovascular and metabolic disorders. Currently, there is no cure for this condition but treatments for general obesity are often used in patients with HS, including surgery, medication and counselling. However, these are mostly ineffective and no medications that are specifically approved for the treatment of HS are available. Specific challenges in HS are because the syndrome represents an adverse effect of different diseases, and that diagnostic criteria, aetiology, pathogenesis and management of HS are not completely defined.

Understanding Phasic Irritability: Anger and Distress in Children's Temper Outbursts

Pediatric irritability can be highly impairing and is implicated in adverse outcomes. The phasic component, characterized by temper outbursts, is a frequent impetus to seek treatment. This study tested whether a previously described anger-distress model of tantrums applies to an outpatient sample of school-age children with clinically impairing temper outbursts (TO; 5.0-9.9 years; N = 86), and examined the clinical relevance of resulting factors through associations with measures of psychopathology, and differences between children with TO and two groups without: children with ADHD (n = 60) and healthy controls (n = 45). Factor analyses established a three-factor model: High Anger, Low Anger, Distress. These factors had unique associations with measures of irritability, externalizing problems, and internalizing problems in the TO group. Additionally, an interaction between groups and outburst factors emerged. Results provide evidence for the presence and clinical utility of the anger-distress model in children's outbursts and suggest avenues for future pediatric irritability research.

Investigating the associations between irritability and hot and cool executive functioning in those with ADHD

BACKGROUND

Irritability is especially pertinent to those with Attention Deficit Hyperactivity Disorder (ADHD) as it is highly prevalent and associated with a more severe clinical presentation and poorer longitudinal outcomes. Preliminary evidence suggests that top-down cognitive processes taking place in emotional contexts (i.e., hot executive functions) as opposed to those evoked in abstract scenarios (i.e., cool executive functions) may be relevant to the presentation of irritability in ADHD. This study explored the cognitive mechanisms underlying irritability in young people with ADHD, hypothesising that irritability would be associated with hot, but not cool, executive function impairments.

METHODS

Our sample included 219 individuals with ADHD. A composite irritability score was derived extracting items from a parent interview, with scores ranging from 0 to 5. Associations were investigated using linear regression analyses, between irritability and four hot tasks measuring sensitivity to risk, risk-taking behaviour following reward or punishment, acceptance of reward delay and reaction to unfair behaviour from others, and two cool tasks measuring set-shifting and motor inhibition.

RESULTS

As hypothesised, there were no significant associations between irritability and cool executive functions in those with ADHD; however, contrary to expectations, there was also no significant evidence that hot executive functions were associated with irritability.

CONCLUSIONS

These results, in a large well characterised sample and using a comprehensive task battery, suggest that the variation in irritability in those with ADHD may not be associated with differences in hot or cool executive function performance.

Characterizing the Neural Correlates of Response Inhibition and Error Processing in Children With Symptoms of Irritability and/or Attention-Deficit/Hyperactivity Disorder in the ABCD Study®

Attention-deficit/hyperactivity disorder (ADHD), characterized by symptoms of inattention and/or hyperactivity and impulsivity, is a neurodevelopmental disorder associated with executive dysfunctions, including response inhibition and error processing. Research has documented a common co-occurrence between ADHD and pediatric irritability. The latter is more characterized by affective symptoms, specifically frequent temper outbursts and low frustration tolerance relative to typically developing peers. Shared and non-shared neural correlates of youths with varied profiles of ADHD and irritability symptoms during childhood remain largely unknown. This study first classified a large sample of youths in the Adolescent Brain Cognitive Development (ABCD) study at baseline into distinct phenotypic groups based on ADHD and irritability symptoms (N = 11,748), and then examined shared and non-shared neural correlates of response inhibition and error processing during the Stop Signal Task in a subset of sample with quality neuroimaging data (N = 5,948). Latent class analysis (LCA) revealed four phenotypic groups, i.e., high ADHD with co-occurring irritability symptoms (n = 787, 6.7%), moderate ADHD with low irritability symptoms (n = 901, 7.7%), high irritability with no ADHD symptoms (n = 279, 2.4%), and typically developing peers with low ADHD and low irritability symptoms (n = 9,781, 83.3%). Latent variable modeling revealed group differences in the neural coactivation network supporting response inhibition in the fronto-parietal regions, but limited differences in error processing across frontal and posterior regions. These neural differences were marked by decreased coactivation in the irritability only group relative to youths with ADHD and co-occurring irritability symptoms and typically developing peers during response inhibition. Together, this study provided initial evidence for differential neural mechanisms of response inhibition associated with ADHD, irritability, and their co-occurrence. Precision medicine attending to individual differences in ADHD and irritability symptoms and the underlying mechanisms are warranted when treating affected children and families.

Does irritability predict attention biases toward threat among clinically anxious youth?

Aberrant threat processing is a known cognitive characteristic of anxiety disorders and irritability. Youth with more severe symptomatology show greater allocation of attention towards threat relative to neutral stimuli. Although irritability contributes to poorer outcomes among anxious youths, irritability has not been considered as a contributing factor to threat processing in anxiety disorders. Thus, the current study examined the role of irritability in predicting attention biases for threat among clinically anxious youth. Our study included 84 clinically anxious youth (M = 9.31 years old, SD = 2.44) who completed a dot-probe task to determine attention biases. Anxiety disorders were assessed using semi-structured diagnostic interviews. Well validated measures were used to assess the severity of anxiety and irritability symptoms via child- and parent-report, respectively. Findings indicated that more severe irritability predicted greater attention biases toward threat among clinically anxious youth, covarying for age, anxiety severity, and the number of comorbid diagnoses. At a trend-level, anxiety severity also predicted attention bias for threat. Among clinically anxious youth, irritability severity was the strongest predictor of attention bias toward threat. Findings point to the salience of irritability, and to some extent anxiety severity, in relation to threat processing among youth with clinical anxiety disorders.