Is Irritability a Top Problem in Youth Mental Health Care? A Multi-informant, Multi-method Investigation

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Association of Irritability with Restricted, Repetitive Behaviors and Social Communication Challenges in Autistic Youth

Although affective irritability is a common and concerning problem for autistic youth, limited research has examined relations among core autism characteristics and irritability. Therefore, this study investigated potential associations among types of restricted/repetitive behaviors (RRBs) and social communication challenges and irritability in autistic children and adolescents. Participants were 107 autistic youth recruited from a university-based autism clinical research program. Two hierarchical multiple regressions were conducted with Affective Reactivity Index as the dependent variable. Covariates were entered at step 1, followed by the independent variables of interest at step 2. For the first model, independent variables of interest were Repetitive Behavior Scale-Revised subscales: stereotyped behavior, self-injurious behavior, compulsive behavior, ritualistic behavior, sameness behavior, and restricted behavior. For the second model, independent variables of interest were Social Responsiveness Scale, Second Edition subscales: social awareness, social cognitive, social communication, and social motivation. Irritability was significantly associated with several categories of RRBs (i.e., insistence on sameness, stereotypic behavior, and restricted interests/activities). Nonetheless, irritability was not associated with categories of social communication and interaction challenges in autistic youth. Results from this study indicated differing associations between core autism characteristics and affective irritability. Findings highlight the importance of differentiating types of restricted, repetitive behaviors and social communication and interaction challenges in conceptualizing mental health concerns in autistic youth.

Irritability: associations with real-time affect dynamics, social interactions, and daily substance use in older adolescents

Irritability is a common and clinically significant symptom associated with a wide range of negative outcomes. Ecological Momentary Assessment (EMA) is a valuable tool for capturing experiences, such as emotions, social interactions, and substance use in real-time, and may be useful in understanding how irritability is related to everyday functioning. We investigated cross-sectional associations between a widely used self-report irritability rating scale and affect dynamics, social interactions, and substance use captured with EMA (5 surveys daily for 14 days) in 349 18-year-olds. We also examined the associations of self- and parent-reported irritability at ages 12 and 15 with the age 18 EMA variables to explore whether these relationships persist over time. Youth-reported irritability at age 18 was linked to greater intensity, variability, and inertia of irritability, sadness, and anxiety, less positive and more negative interpersonal experiences, and greater cigarette and drug use. Most effect sizes were in the medium-small range. Associations of youth- and parent-reported irritability at ages 12 and 15 with the age 18 EMA measures were generally similar, although smaller in magnitude. Findings contribute to understanding how irritability is manifested in real-time affect dynamics and interpersonal functioning, as well as daily substance use. Most effects were evident over the course of up to 6 years - that is, early adolescent irritability, reported by both youth and their parents, was associated with similar real-time affect dynamics and interpersonal experiences at age 18. This study contributes to the literature on the developmental psychopathology of irritability by extending findings to everyday functioning.

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.

Parent and Teacher Ratings of Tonic and Phasic Irritability in a Clinical Sample

Research on tonic (persistently angry or grumpy mood) and phasic (temper tantrums/outbursts) irritability in youth has utilized community samples and information from parents and youth. We examined whether tonic and phasic irritability are empirically distinguishable and have similar correlates using teacher, in addition to parent, reports in a clinical sample of children and adolescents. The sample included youth aged 5-18 evaluated at a university outpatient clinic, with complete information from 2481 parents and 2449 teachers. We conducted confirmatory factor analysis (CFA) using items from several parent- and teacher-report inventories and examined concurrent associations with psychopathology and functioning. The CFA supported a two-factor model consistent with tonic and phasic irritability in both parent- and teacher-reports. Parent-reported tonic irritability was associated with higher rates of depression and anxiety disorders, suicidality, and antidepressant medication use. Teacher-reported tonic irritability was associated with elevated rates of depression and antidepressant use. Both parent- and teacher-reported phasic irritability were linked to higher rates of ADHD combined type, oppositional defiant/conduct disorders, and referral for rages. Parent- and teacher-reported tonic and phasic irritability were all associated with impaired social functioning. Parents and teachers can distinguish tonic and phasic irritability, which are associated with internalizing and externalizing problems, respectively. Findings were generally consistent across informants, and with prior studies using community samples.

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.

Peer functioning difficulties may exacerbate symptoms of attention-deficit/hyperactivity disorder and irritability over time: a temporal network analysis

BACKGROUND

Children with attention-deficit/hyperactivity disorder (ADHD) have been consistently found to experience impairments in peer functioning. Irritability is highly prevalent in children with ADHD and may worsen social impairments given the frequent temper outbursts and low frustration tolerance characterizing irritability. However, it is still unclear how ADHD and irritability symptoms interact with peer functioning difficulties over time. Assessing these temporal dynamics using a novel longitudinal approach (i.e., temporal network analysis) may reveal precise targets for intervention.

METHODS

This study investigates the dynamic associations between ADHD symptoms, irritability, and peer functioning in a community sample of 739 children (ages 8-11 years, Mage = 10.06 [SD = 0.59], 47.77% females) assessed at three timepoints, 6 months apart, in a school-based study. Parents reported their child's ADHD symptoms using the Swanson, Nolan, and Pelham Rating Scale (SNAP-IV), and irritability symptoms using the Child Behavior Checklist (CBCL) irritability items. Children's peer functioning (i.e., peer acceptance, peer rejection, number of friendships, and victimization) was measured via peer nomination. To estimate the longitudinal associations between the variables, we built a graphical vector autoregression model for panel data.

RESULTS

The longitudinal network highlighted that poor peer functioning contributed to increases in symptoms over time. Specifically, (1) physical victimization predicted increases in inattention, hyperactivity, and irritability; (2) peer rejection predicted increases in inattention, which in turn predicted increases in irritability; (3) peer acceptance predicted decreases in inattention and irritability; and (4) higher numbers of mutual friendships increased inattention.

CONCLUSIONS

These results suggest that a negative social environment involving physical bullying and rejection may aggravate ADHD and irritability symptoms. Conversely, positive social interactions, such as being liked by peers, may improve inattention and irritability symptoms. Fostering social-emotional skills and positive social interactions and environments in children with ADHD and irritability may be a promising target for future interventions to reduce symptoms.

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.

Validity of the Korean Version of the Brief Irritability Test in Psychiatric Patients

OBJECTIVE

This study aimed to investigate the validity and reliability of the Korean version of the Brief Irritability Test (BITe) and adapt it for Korean patients with psychiatric disorders.

METHODS

A total of 296 patients at the Department of Psychiatry of Hanyang University Guri Hospital completed the BITe, Korean Beck Depression Inventory-II, Korean Beck Anxiety Inventory, the Korean version of the State-Trait Anger Expression Inventory, and Barratt Impulsiveness Scale-11. Construct validity was confirmed through exploratory factor analysis (EFA) and confirmatory factor analysis (CFA). Reliability testing included assessments of internal consistency (Cronbach's α) and item-total correlations. Convergent validity was examined through correlational analyses with variables such as anxiety, depression, anger, and impulsivity.

RESULTS

First, the scale had good internal consistency with a Cronbach's α of 0.88. Second, EFA indicated a single dimensionality of the BITe, and CFA demonstrated a reasonable fit for the single-factor model (comparative fit index=0.97, Tucker-Lewis Index=0.95, normed fit index=0.97, goodness-of-fit index=0.96, root mean square error of approximation=0.12, standardized root mean residual=0.03). Finally, the convergent validity analysis revealed a significant positive correlation with depression, anxiety, and anger, except for anger control, which is a sub-variable of anger.

CONCLUSION

The results showed that the Korean version of the BITe had good psychometric properties, and might serve as a valuable tool for assessing irritability in Korean patients with psychiatric disorders.

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.

Evidence Base Update on the Assessment of Irritability, Anger, and Aggression in Youth

OBJECTIVE

Irritability, anger, and aggression have garnered significant attention from youth mental health researchers and clinicians; however, fundamental challenges of conceptualization and measurement persist. This article reviews the evidence base for assessing these transdiagnostic constructs in children and adolescents.

METHOD

We conducted a preregistered systematic review of the evidence behind instruments used to measure irritability, anger, aggression, and related problems in youth. Searches were conducted in PsycINFO and PubMed, identifying 4,664 unique articles. Eligibility criteria focused on self- and proxy-report measures with peer-reviewed psychometric evidence from studies in English with youths ages 3-18. Additional measures were found through ancillary search strategies (e.g. book chapters, review articles, test publishers). Measures were screened and coded by multiple raters with acceptable reliability.

RESULTS

Overall, 68 instruments met criteria for inclusion, with scales covering irritability (n = 15), anger (n = 19), aggression (n = 45), and/or general overt externalizing problems (n = 27). Regarding overall psychometric support, 6 measures (8.8%) were classified as Excellent, 46 (67.6%) were Good, and 16 (23.5%) were Adequate. Descriptive information (e.g. informants, scales, availability, translations) and psychometric properties (e.g. reliability, validity, norms) are summarized.

CONCLUSIONS

Numerous instruments for youth irritability, anger, and aggression exist with varying degrees of empirical support for specific applications. Although some measures were especially strong, none had uniformly excellent properties across all dimensions, signaling the need for further research in particular areas. Findings promote conceptual clarity while also producing a well-characterized toolkit for researchers and clinicians addressing transdiagnostic problems affecting youth.

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.

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.

Irritability and Temperament: Concurrent and Prospective Relationships in Childhood and Adolescence

OBJECTIVE

Irritability symptoms are closely associated with, and may reflect, temperament traits, particularly negative affectivity (NA). However, there are few empirical data on the relationships between child temperament and irritability symptoms.

METHOD

We investigated cross-sectional and longitudinal relationships between irritability symptoms and temperament traits from age 3-15 in a community sample of 609 children and their parents. Irritability symptoms were assessed through structured interviews with parents at ages 3/6, and inventories completed by parents and youth at ages 12/15. Temperament traits were assessed using parent reports at ages 3/6, and parent and child reports at ages 12/15. Path analysis and structural equation modeling were used to explore longitudinal associations from ages 3-6 and 12-15, respectively.

RESULTS

Higher levels of irritability symptoms at ages 3/6 were concurrently associated with higher levels of NA and lower levels of effortful control (EC). In adolescence, higher irritability symptoms were concurrently associated with higher negative temperament and disinhibition. In longitudinal analyses from age 3-6 and 12-15, irritability symptoms showed modest but significant stability after adjusting for the stability of temperament traits. However, there were significant differences in the stability paths at age 3-6, reflecting lower stability of irritability symptoms. Finally, EC at age 3 predicted increased irritability symptoms at age 6, while irritability symptoms at age 3 predicted increased NA at age 6.

CONCLUSION

Irritability symptoms are robustly associated with both temperamental NA and difficulty regulating attention and behavior. These findings help situate irritability symptoms within widely accepted temperament/personality taxonomies.

Executive function in children with disruptive mood dysregulation disorder compared to attention-deficit/hyperactivity disorder and oppositional defiant disorder, and in children with different irritability levels

Addressing current challenges in research on disruptive mood dysregulation disorder (DMDD), this study aims to compare executive function in children with DMDD, children with attention-deficit/hyperactivity disorder (ADHD), and children with oppositional defiant disorder (ODD). We also explore associations between irritability, a key DMDD characteristic, and executive function in a clinical sample regardless of diagnosis. Our sample include children (6-12 years) referred to child psychiatric clinics. Measures of daily-life (parent-reported questionnaire) and performance-based (neuropsychological tasks) executive function were applied. Identifying diagnoses, clinicians administered a standardized semi-structured diagnostic interview with parents. Irritability was assessed by parent-report. First, we compared executive function in DMDD (without ADHD/ODD), ADHD (without DMDD/ODD), ODD (without DMDD/ADHD) and DMDD + ADHD (without ODD). Second, we analyzed associations between executive function and irritability using the total sample. In daily life, children with DMDD showed clinically elevated and significantly worse emotion control scores compared to children with ADHD, and clinically elevated scores on cognitive flexibility compared to norm scores. Children with DMDD had significantly less working memory problems than those with ADHD. No differences were found between DMDD and ODD. Increased irritability was positively associated with emotional dyscontrol and cognitive inflexibility. For performance-based executive function, no diagnostic differences or associations with irritability were observed. We discuss how, in daily life, children with high irritability-levels get overwhelmed by feelings without accompanying regulatory capacities.

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.

Neural correlates of irritability symptom relief in adolescents pre- and post-trauma-focused cognitive behavioral therapy: A pilot study on reward processing

Despite that Trauma-Focused Cognitive Behavioral Therapy (TF-CBT) is a first-line, evidence-based treatment for youths experiencing trauma-related symptoms, treatment responses vary and it remains unclear for whom and how this treatment works. In this context, we examined pre-treatment neural reward processing and pre- vs. post-treatment changes in neural reward processing, in relation to irritability - a transdiagnostic and dimensional feature present in multiple trauma-related syndromes, following TF-CBT. Adolescents (N = 22) with childhood trauma history completed a child-friendly monetary incentive delay task during fMRI acquisition, prior to and after the treatment, and irritability symptoms were assessed at five time points over the course of the treatment. Individual irritability slopes (i.e., irritability change rate) and intercepts (i.e., initial irritability level), generated by linear growth curve modeling, were integrated with fMRI data. Repeated ANCOVAs demonstrated that both pre-treatment neural response to reward and pre- vs. post-treatment changes in neural reward processing correlated with irritability symptom relief, such that opposite baseline neural reward processing profiles and differential changing patterns were observed in individuals showing irritability symptom relief vs. not. Together, our findings provide proof of concept that integrating brain information with clinical information has the potential to identify predictors and mechanisms of symptom relief.

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.