Roads Diverged: Developmental Trajectories of Irritability From Toddlerhood Through Adolescence

Caregivers' Attention Toward, and Response to, Their Child's Interoceptive Hunger and Thirst Cues

People can use their internal state to determine if they are hungry or thirsty. Although the meaning of some interoceptive cues may be innate (e.g., pain), it is possible that others-including those for hunger and thirst-are acquired. There has been little exploration of this idea in humans. Consequently, we conducted a survey among child caregivers to determine if the basic conditions necessary for interoceptive learning were present. Two-hundred and thirty-five caregivers of children aged 1-12 years were asked if they had recently noticed stomach rumbling, hunger-related irritability, and a dry mouth in their child. They were also asked how they would respond. The impact of several moderating variables, especially caregiver beliefs about the causes of hunger, fullness, and thirst, was also explored. Fifteen percent of caregivers had recently noticed stomach rumbling in their child, 28% hunger-related irritability, and 14% a dry mouth. Forty-four percent of caregivers had noticed at least one of these three cues. Noticing hunger cues was significantly moderated by caregiver beliefs about their cause, by child age, and in one case by temporal context (around vs. outside mealtimes). Key caregiver responses were providing the need (e.g., offer food) and/or asking the child if they had a need (e.g., hungry?). Each type of response could potentially support a different form of interoceptive learning. In conclusion, we suggest the necessary conditions for children to learn interoceptive hunger and thirst cues, are present in many caregiver-offspring dyads.

Neural mechanisms of inhibitory control in preadolescent irritability: Insights from the ABCD study

OBJECTIVE

Elevated pediatric irritability is a transdiagnostic symptom that predicts multiple mental health problems in adolescence and adulthood. Altered top-down regulatory networks, such as inhibitory control networks that suppress an impulse in favor of goal-directed behavior, are thought to contribute to high levels of youth irritability. Nevertheless, little work has examined links between youth irritability and neural processes supporting inhibitory control in large diverse samples, nor have they focused on the key period ramping up to adolescence (i.e., preadolescence).

METHOD

Functional MRI data from 5380 preadolescents (age M=9.97 years, SD=0.62) in the baseline Adolescent Brain and Cognitive Development (ABCD) Study were analyzed. Parents reported on their preadolescent's irritability. The stop signal task (SST) was leveraged to probe successful and failed inhibitory control. Activation and functional connectivity with amygdala, ventral striatum, and prefrontal seed regions were calculated during the SST and used in whole brain and region of interest (ROI) group-level analyses evaluating irritability effects.

RESULTS

Preadolescents with higher levels of irritability displayed decreases in functional connectivity among amygdala, ventral striatum, and prefrontal cortex regions during both successful and failed inhibitory control conditions. These results remained after adjusting for co-occurring anxiety, depression, and attention-deficit/hyperactivity symptoms.

CONCLUSIONS

Findings suggest neural aberrations in inhibitory control play a role in the pathophysiology of preadolescent irritability and associations are not merely due to co-occurring symptoms. Neural mechanisms of inhibitory control associated with irritability may provide novel intervention targets.

Foster Care Leads to Lower Irritability Among Adolescents with a History of Early Psychosocial Deprivation

Irritability reflects a propensity for frustration and anger, and is a transdiagnostic symptom of both externalizing and internalizing psychopathology. While early adverse experiences are associated with higher levels of irritability, experiences of early psychosocial deprivation and whether family-based placements can mitigate the impact on subsequent irritability, remain underexplored. The current study examined irritability in 107 16-year-olds with a history of institutional care from a randomized controlled trial of foster care as an alternative to institutional care and 49 community comparison children. At age 16 years, irritability was assessed using parent- and self-report forms of the Affective Reactivity Index. Compared to community adolescents, those with a history of institutional care exhibited significantly elevated irritability levels. Among those who experienced institutional care, those randomized to foster care had lower levels of irritability compared to participants randomized to the care-as-usual group, and this effect persists after controlling for baseline negative emotionality. These findings suggest a causal link between high-quality foster care and lower irritability following psychosocial deprivation. Additionally, longer duration in institutional care and non-family placement at age 16 years were associated with higher levels of irritability, highlighting the role of caregiving in explaining variation in irritability in adolescence. Policies that support long-term, high-quality family placements for children without regular caregivers should be prioritized.

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.

Irritability across adolescence: Examining longitudinal trajectory, stability, and associations with psychopathology and functioning at age 18

BACKGROUND

Irritability, marked by diminished frustration tolerance, holds significant implications for youth mental health treatment. Despite prior research on irritability trajectories, understanding of individual differences during adolescence remains limited. This study examines the stability and trajectory of irritability across ages 12-18, investigating associations with psychopathology and functioning at age 18.

METHODS

A community sample of families with 3-year-old children (N = 518) was recruited via commercial mailing lists. Irritability was assessed at ages 12, 15, and 18 using the Affective Reactivity Index. Psychopathology at age 18 was evaluated with the Kiddie Schedule for Affective Disorders and Schizophrenia, and functioning was assessed through the UCLA Life Stress Interview. Measurement invariance analyses and latent growth curve modeling were conducted within a structural equation modeling (SEM) framework.

RESULTS

Configural, metric, and scalar invariance models were supported. Elevated irritability at age 12 predicted adverse outcomes at age 18, including increased psychotropic medication use, mental health treatment, suicidal ideation, self-injury, and psychiatric disorders. Importantly, these associations persisted even after accounting for corresponding variables at age 12. The trajectory of irritability during early adolescence significantly predicted heightened risks for various outcomes at age 18, including suicidal ideation, depression, anxiety, disruptive behavior disorders, and impaired interpersonal functioning.

DISCUSSION

Limitations include using only youth-reported data at age 18, limited generalizability from a mostly White, middle-class sample, and insufficient exploration of the broader developmental trajectory of irritability. Nevertheless, the findings emphasize the crucial role of irritability's trajectory in influencing various psychopathological and functional outcomes in late adolescence.

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.

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.

Cross-Sectional and Longitudinal Relations Among Irritability, Attention-Deficit/Hyperactivity Disorder Symptoms, and Inhibitory Control

OBJECTIVE

Irritability and attention-deficit/hyperactivity disorder (ADHD) symptoms frequently co-occur in youth. Although ADHD has been associated with inhibitory control deficits, the literature on irritability and inhibitory control is mixed. Examining how irritability, ADHD symptoms, and inhibitory control interrelate both cross-sectionally and longitudinally across development could shed light on common and distinct mechanisms of youth psychopathology.

METHOD

We utilized a cross-lagged panel model with data from 2 time points (at ages 10 and 12 years) of the Adolescent Brain and Cognitive Development (ABCD) Study (N = 7,444, or ∼63% of the baseline sample with full data at each time point) to test cross-sectional and longitudinal associations among parent-reported irritability and ADHD symptoms and behaviorally assessed inhibitory control. This was performed separately across discovery and replication subsamples, each n = 3,722.

RESULTS

As expected, irritability and ADHD symptoms exhibited strong cross-sectional and reciprocal cross-lagged associations. Higher ADHD symptoms at age 10 years were associated concurrently with poorer inhibitory control and predicted poorer inhibitory control at age 12. Contrary to predictions, inhibitory control was not significantly associated with irritability cross-sectionally, nor was it predictive of later irritability or ADHD symptoms.

CONCLUSION

These findings highlight strong links between irritability and ADHD. Although inhibitory control deficits were linked to ADHD and predictive of its symptom course, inhibitory control had no significant associations with irritability. Future research should investigate other candidate mechanisms of the co-occurrence of irritability and ADHD symptoms and predictors of their developmental trajectories.

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.

Characterizing the spectrum of irritability in preadolescence: Dimensional and pragmatic applications

OBJECTIVES

Characterize the dimensional spectrum of preadolescent (PA) irritability, a robust transdiagnostic vulnerability marker, using the youth version of the Multidimensional Assessment Profiles Temper Loss (MAPS-TL-Youth) scale including common and with developmentally specific items. Based on this, derive and validate a clinically optimized irritability screener to flag psychopathology risk in preadolescents.

METHODS

The normal:abnormal irritability spectrum was modeled using MAPS-TL-Youth data from the Multidimensional Assessment of Preschoolers Study (MAPS) Study PA wave (n = 340) via item response theory. Both cross-cutting core items from the MAPS scales and developmentally specific items were used to generate this dimension. Stepwise logistic regression was then used to optimize MAPS-TL-Youth irritability items in relation to Kiddie Schedule of Affective Disorders and Schizophrenia impairment to generate a clinically optimized irritability screener. Receiver operator characteristic analysis identified the irritability threshold for the screener. For the first time, youth self-report of their own irritability on the MAPS-TL was also modeled via the MAPS-TL-Youth-Self-Report (MAPS-TL-Youth-SR).

RESULTS

Irritability was unidimensional and ranged from mild and common to severe and rare behaviors. Developmentally specific items allowed detection of more severe irritability. Items for the screener were identified in relation to concurrent impairment. These included low frustration tolerance and pathognomonic severe behaviors. The clinically optimized screener demonstrated very good sensitively (87%) and specificity (81%) in regard to concurrent irritability-related DSM disorders. Modeling of the MAPS-TL-Youth-SR yielded similar results.

CONCLUSION

Characterizing the normal: abnormal spectrum of irritability in preadolescence advances application of Research Domain Criteria methods to this developmental period. This foundational work yielded two developmentally specified tools for irritability characterization in preadolescence: a nuanced dimensional scale to precisely characterize the full normal-abnormal irritability spectrum, and a pragmatic, clinically optimized screener suitable for real world use. Future application in mechanistic and clinical studies will be important for establishing validity and incremental utility.

Developmentally specified characterization of the irritability spectrum at early school age: Implications for pragmatic mental health screening

OBJECTIVES

Developmentally specified measures that identify clinically salient irritability are needed for early school-age youth to meaningfully capture this transdiagnostic risk factor for psychopathology. Thus, the current study modeled the normal:abnormal irritability spectrum and generated a clinically optimized screening tool for this population.

METHODS

The irritability spectrum was modeled via the youth version of the Multidimensional Assessment Profile Scales-Temper Loss Scale (MAPS-TL-Youth) in children (n = 474; 6.0-8.9 years) using item response theory (IRT). Both cross-cutting core irritability items from the early childhood version and new developmentally specific items were included. Items uniquely associated with impairment were identified and used to derive a brief, clinically optimized irritability screener. Longitudinal data were then utilized to test the predictive utility of this clinically optimized screener in preadolescence (n = 348; 8.0-12.9 years).

RESULTS

Most children exhibit irritability regularly, but daily occurrence was rare. Of the top 10 most severe items from the IRT analyses, 9 were from the developmentally specific items added for the MAPS-TL Youth version. Two items associated with concurrent impairment were identified for the clinically optimized irritability screener ("Become frustrated easily" and "Act irritable"). The MAPS-TL-Youth clinically optimized screener demonstrated good sensitivity (69%) and specificity (84%) in relation to concurrent DSM 5 irritability-related diagnoses. Youth with elevated scores on the screener at early school age (ESA) had more than 7x greater odds of irritability-related psychopathology at pre-adolescence.

CONCLUSIONS

The MAPS-TL-Youth characterized the developmental spectrum of irritability at ESA and a clinically optimized screener showed promise at predicting psychopathology risk. Rigorous testing of clinical applications is a critical next step.

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.

Editorial: Roads Less Traveled: New Directions for Novel Outcomes in Youth Irritability Research

Road metaphors are ubiquitous in youth mental health. Developmental psychopathology research is described in terms of pathways, trajectories, cascades, and transitions. Children's behavioral concerns are discussed as warning signs and rough spots. Although these metaphors have long been useful abstractions, modern quantitative methods and large-scale longitudinal studies have made it possible to empirically investigate the "roads" traveled by individuals across development. One goal here is to chart the paths most often followed by different subgroups of youth. Another goal involves surveying variables that nudge children toward (or away from) psychopathology and other key outcomes. These 2 goals-finding trajectories and predictors thereof-have important implications for research, intervention, and policy; and some of the most important studies, in our view, accomplish both.