Joint Consideration of Inhibitory Control and Irritability in Young Children: Contributions to Emergent Psychopathology

Irritability, Negative Life Events and the Course of Anxiety and Depressive Symptoms in a Clinical Sample of Youth: A Longitudinal Study

Objective

Irritability, the tendency to react with anger, and the experience of negative life events (NLE) have independently been associated with the emergence of anxiety and depression. Here, we investigate how irritability and cumulative effects of NLE interactively predict the course of anxiety and depression in the context of common psychiatric disorders.

Method

432 youth with no psychiatric diagnosis, or a diagnosis of an anxiety disorder, Attention-Deficit/ Hyperactivity Disorder (ADHD), or Disruptive Mood Dysregulation Disorder (DMDD), participated in this study. At baseline, we assessed NLE, parent and youth reports of irritability and anxiety, and youth reports of depression. Symptoms were annually reassessed for up to four years.

Results

In youth without psychiatric diagnoses but with elevated baseline irritability, the presence of NLE predicted decreasing anxiety, while the absence of NLE predicted increasing anxiety. In youth with an anxiety disorder, elevated baseline irritability predicted decreasing anxiety independent of NLE, while a large cumulative effect of NLE predicted increasing depression. NLE predicted persisting mild anxiety in ADHD and persisting mild depressive symptoms in DMDD.

Conclusion

Our findings suggest that, particularly in non-referred samples, NLE might moderate the relationship between irritability and future anxiety such that irritability/ anger in the context of NLE can positively affect the course of anxiety. Future work replicating this finding while repeatedly measuring NLE and rigorously controlling for potentially confounding effects of treatment, is warranted.

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.

Editorial: Neuropsychological Correlates of Irritability Accompanying Symptoms of Attention-Deficit/Hyperactivity Disorder: Clues and Pitfalls

Attention-deficit/hyperactivity disorder (ADHD) is one of the most common neurodevelopmental disorders and is characterized by developmentally inappropriate, pervasive, and impairing symptoms of inattention and/or hyperactivity/impulsivity.1 Although not listed among the core symptoms, irritability, reduced tolerance to frustration, and labile mood are considered features associated with ADHD.1,2 Irritability refers to a tendency to get angry quickly and/or easily at a lower threshold of frustration and respond disproportionately to triggers.3 Almost two-thirds of youth with ADHD may display impairing irritability, while rates of ADHD may be elevated among youth with clinically significant irritability.2 Irritability and impulsivity are thought to share neurobiological mechanisms that may overlap with executive and self-regulatory functions such as inhibitory control.3-5 The nature and developmental stability of these associations are still debated. Areas of controversy include the role of emotion regulation problems in positive vs negative emotions for impairment6; relations between those problems and risk-taking behavior, hyperactive-impulsive symptoms, and disruptive behavior problems2-5; and the nature of emotion regulation problems (ie, as core symptoms, as a feature of a variant of ADHD, or as a characteristic of specific comorbidities such as depression).2.

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.