The Affective Side of Disruptive Behavior: Toward Better Understanding, Assessment, and Treatment

ABSTRACT

Historically, much of the progress made in youth mental health research can be classified as focusing on externalizing problems, characterized by disruptive behavior (e.g. aggression, defiance), or internalizing problems, characterized by intense negative affect (e.g. depression, anxiety). Until recently, however, less attention has been given to topics that lie somewhere in between these domains, topics that we collectively refer to as the affective side of disruptive behavior. Like the far side of the moon, the affective side of disruptive behavior captures facets of the phenomenon that may be less obvious or commonly overlooked, but are nonetheless critical to understand. This affective side clarifies socially disruptive aspects of traditionally “externalizing” behavior by elucidating proximal causation via intense negative affect (traditionally “internalizing”). Such problems include irritability, frustration, anger, temper loss, emotional outbursts, and reactive aggression. Given a recent explosion of research in these areas, efforts toward integration are now needed. This special issue was developed to help address this need. Beyond the present introductory article, this collection includes 4 empirical articles on developmental psychopathology topics, 4 empirical articles on applied treatment/assessment topics, 1 evidence base update review article on measurement, and 2 future directions review articles concerning outbursts, mood, dispositions, and youth psychopathology more broadly. By deliberatively investigating the affective side of disruptive behavior, we hope these articles will help bring about better understanding, assessment, and treatment of these challenging problems, for the benefit of youth and families.

The Far Side of the Moon

For most observers, only one side of the moon can ever be seen. This near side of the moon faces Earth in an unvaryingly fixed direction due to tidal locking. As the moon orbits the Earth, light from the sun makes varying aspects of this near side of the moon’s surface differentially visible. Throughout all phases of the lunar cycle, we continue to see only this side of the moon. This phenomenon is displayed in Figure 1, across the four major lunar phases (panels a–d), where it clearly shows the same topography, but with different parts lit up at different times. The near side of the moon (panel e) has been visible in this way throughout human history. Expectations generated by common descriptions, enhanced by pareidolia, have led to perceptions of, and myths about, a “man in the moon” in global societies over millennia. In short, we feel very familiar with the moon as represented by its near side (NASA, 2023).

Figure 1. Sides and phases of the moon.

Note. Images are from Wikimedia Commons by Tomruen (a–d; public domain) and NASA/GSFC/Arizona State University (e–j; used in accordance with citation policy). https://commons.wikimedia.org/wiki/File:Lunar_libration_with_phase_Oct_2007.gif; http://lroc.sese.asu.edu/news/index.php?/archives/790-A-Unique-View-Of-The-Moon.html; https://www.lroc.asu.edu/posts/242; https://www.lroc.asu.edu/posts/237.

In contrast, we have only just begun to get acquainted with the far side of the moon (see Figure 1, panel f). The “dark side of the moon” is a misnomer for this far side, the side not visible to Earth-bound observers. In this context, “dark” represents an absence of knowledge rather than an absence of light. Indeed, the far side is almost entirely unknown to humankind. It was only in the late 1950s and 1960s that early Soviet and American space missions caught their first glimpses of it through satellite photography and manned flybys. In the more than half-century since then, we have made incremental progress toward understanding the moon from its far side and related vantage points (see Figure 1, panels g–j), slowly contributing to a better understanding of the moon as a whole. Having set foot on the near side more than 50 years ago, it is only in the last 5 years that humans have landed unmanned crafts in the moon’s lesser-known regions. Future explorations of the far side are thought to hold great potential, from building lunar telescopes to peer into corners of space not visible to earthbound astronomers (Dinner, 2023), to the discovery of water in the polar regions (Reach et al., 2023), to mining helium-3 isotopes as a potential clean source of nuclear energy that could power society in the years to come (Simko & Gray, 2014). These are exciting far-side possibilities.

The Affective Side of Disruptive Behavior

Why talk about lunar science in this special issue of the Journal of Clinical Child and Adolescent Psychology (JCCAP)? We do so because the history of human engagement with the moon is a useful metaphor for the history of characterizing disruptive behavior problems in youth mental health research.¹ People are very familiar with the near side of these phenomena—with the manifest presentations, diagnoses, and symptoms of Oppositional Defiant Disorder (ODD), Conduct Disorder (CD), Attention-Deficit/Hyperactivity Disorder (ADHD), as well as with other systematic descriptions of externalizing problems (e.g., aggressive behavior, bullying, rule-breaking, delinquency). Similar to the near side of the moon, the behavioral aspects of these phenomena are salient, readily observed, familiar, and even at times expected by the observer. When they occur, they command the observer’s attention. They typically exert a powerful impact on the environment. For instance, overt disruptive behavior problems are among the most common reasons for visits to outpatient clinics (Olfson et al., 2014), emergency departments (Benarous et al., 2019), inpatient units (Rice et al., 2002), and day programs (Martin et al., 2017), as well as for school disciplinary referrals (Spaulding et al., 2010) and juvenile arrests (Puzzanchera et al., 2022). Externalizing problems are also some of the most highly prevalent conditions in the population (Merikangas et al., 2010; Polanczyk et al., 2015), irrespective of whether or not the individuals affected by them receive any clinical attention. Their lifetime impact on public health and service sectors is enormous.

Table 1. Terms used to describe internalizing vs. externalizing problems and disorders.

Internalizing	Externalizing
Emotional	Disruptive
Over-controlled	Under-controlled
Manifested inward	Manifested outward
Self-directed	Other-directed
Inhibited	Disinhibited
Withdrawal	Approach
Avoidant	Antisocial

For example, consider results from the National Comorbidity Survey – Adolescent Supplement. As shown in Table 2, externalizing disorders were found to be quite common and impairing in the population, with adolescent lifetime prevalence estimates of 8.7% for ADHD, 12.6% for ODD, and 6.8% for CD (Merikangas et al., 2010). The same study found that 59.8% of adolescents with ADHD and 45.4% of those with either ODD or CD received disorder-specific mental health treatment in their lifetime, higher than the corresponding rates for mood or anxiety disorders (Merikangas et al., 2011). Taken together, these findings suggest that roughly 2.2–6.8% of adolescents in the population are treated for at least one externalizing disorder in their lifetime, rates greater than anxiety disorders (0.5–1.3%) and comparable to major depressive disorders (4.6%; see Table 2). In other words, externalizing problems are not only common, but also commonly get noticed in a manner that leads to referrals and services at greater rates than other kinds of problems.² Much like the near side of the moon, the manifest behaviors of externalizing problems are familiar, salient, and perhaps more readily acted upon than the other kinds of phenomena or other aspects of the same phenomenon.

Table 2. Youth mental health prevalence and service use estimates from the NCS-A study.

	Lifetime disorder prevalence in the population (%)^a		Lifetime disorder-specific mental health service use among those with disorder (%)^b	Lifetime prevalence of disorder-specific service use in the population (%)^c
	Overall	With severe impairment		Overall	With severe impairment
Internalizing disorders
Generalized anxiety disorder	2.2	0.9	43.8	1.0	0.4
Social phobia	9.1	1.3	12.1	1.1	0.2
Specific phobia	19.3	0.6	6.5	1.3	<0.1
Separation anxiety disorder	7.6	0.6	6.9	0.5	<0.1
Major depressive disorder^d	11.7	8.7	39.4	4.6	3.4
Externalizing disorders
ADHD	8.7	4.2	59.8	5.2	2.5
Oppositional defiant disorder	12.6	6.5	53.8	6.8	3.5
Conduct disorder	6.8	2.2	32.3	2.2	0.7

Note. NCS-A = National Comorbidity Survey – Adolescent Supplement, ADHD = Attention-Deficit/Hyperactivitiy Disorder. ^aLifetime disorder prevalence estimates are drawn from Merikangas et al. (2010), Table 2. ^bLifetime service use estimates from Merikangas et al. (2011), Table 1. ^cLifetime prevalence of service use estimates were computed as the product of the prevalence rate and the service use rate. ^dIncludes dysthymia.

Also similar to the moon, scientific study has led to a refinement of the understanding of disruptive behavior. Understandably, earlier efforts to describe the landscape of disruptive behavior aimed to draw coherence from what could be seen at the time. For instance, moral defect (Still, 1902) was a unified description of impulsivity, hyperactivity, callousness, oppositionality, theft, deficient affective responding, tantrums, and other observed behaviors. Later, Levy (1955) presented a model of negativism that suggested a fundamental behavioral commonality underlying defiance in childhood, anorexia nervosa in adolescence, and catatonic schizophrenia in adulthood. Similarly, prior to the adoption of modern diagnostic categories like ADHD, Specific Learning Disorder, and ODD, the term minimal brain dysfunction was used to represent a syndrome variously characterized by such features as specific learning deficits, hyperactivity, inattention, impulsivity, emotional lability, and perceptual-motor deficits (Clements & Peters, 1962). Over time, scientific exploration has left these broad and overwhelming descriptions behind. We have traded in low-resolution images for sharper and surer maps of the behavioral landscape, arguably serving to guide more effective treatment efforts and bring relief to individuals and families.

As another testament to the near-side nature of disruptive behavior, the methods used for assessing youth externalizing problems rely heavily on externally observable, objective behavioral indicators. Many of the instruments for assessing ODD, CD, and ADHD (e.g., Pelham et al., 1992; Swanson et al., 2012) map directly onto their observable diagnostic criteria (Burke et al., 2024). Perhaps it is no surprise that, given their objective behavioral indicators, ODD, CD, and ADHD are some of the most reliably diagnosed mental health conditions, with interrater reliability estimates consistently falling in the “good” range or higher in DSM-5 and ICD-11 field trials (Regier et al., 2013; Robles et al., 2022). To be sure, these are distinct diagnostic categories with large literatures and recent developments that are beyond the scope of this article and special issue (for some recent “state of the science” overviews, see Fairchild et al., 2019; Faraone et al., 2024; Hawes et al., 2023). Still, it can be said that a great deal has been learned about the assessment, treatment, phenomenology, and course of disruptive behavior problems. Much like the near side of the moon, we have accumulated a considerable amount of knowledge through study of these directly observable behaviors.

But there is still much to learn. As with the far side of the moon, we contend that there is a “far side” to externalizing problems, which we refer to as the affective side of disruptive behavior. This concept draws attention to facets of negative affect reliably associated with manifest disruptive behaviors. For our purposes, the far side represents patterns of intense negative affect dysregulation that often underlies disruptive behavior problems, including irritability, frustration, anger, temper loss, emotional outbursts, and reactive aggression, as some common examples.

It is of course not particularly novel to note the correspondence between disruptive behavior and these kinds of affective experiences. Historically, researchers, clinicians, parents, and teachers have tended to view these problems as a relatively undifferentiated part of the heterogenous spectrum of externalizing concerns, with predominant distinctions emphasizing the external environment—i.e., whether the problems were overt vs. covert, or destructive vs. nondestructive (Frick et al., 1993)—instead of the underlying drivers. For example, the touchy-angry-temper symptoms have been a core part of the ODD criteria since DSM-III-R in 1987, squarely lumped in among other overt oppositional behaviors such as arguing and defying. Thus, negative affect is clearly and empirically an important aspect of the overt externalizing spectrum, even where the focus is primarily on behavioral indicators. And given that a child’s affect is different (e.g., less obvious) than their behavior, and it is measured with different instruments, we may not notice it as readily, or we may view it as a correlate rather than as part of the whole.

If there is a novel aspect to our effort, it is to push for refinement in the study of this landscape that avoids some pitfalls that seem evident to us, and which arguably have restricted the clarity in any maps to guide treatment and explanation of the affective side of disruptive behavior. It is precisely because of this obfuscation, not in spite of it, that we find such great promise in the scientific exploration of the affective side. Research over the last 2 decades—on topics like irritability (Leibenluft et al., 2024), emotion dysregulation (Sheppes et al., 2015), and higher-order models of psychopathology (Kotov et al., 2021)—have all made laudable progress toward describing the nature of negative affect in disruptive behavior problems.

The potential pitfalls that concern us relate to efforts that seem to prioritize either one of these aspects in ways that obscure rather than clarify the landscape. For example, the concept of masked depression suggested that overactivity, pyromania, school problems in children, and antisocial behavior in adolescents were indicators of an underlying depression (e.g., Modai et al., 1982), even when no dysphoric mood, anhedonia nor other symptoms of depression were reported.³ The term masked depression may be out of fashion, but assertions about prioritizing—even presuming—affective disorders while disregarding manifest disruptive behavior remain common (e.g., Beltrán et al., 2021; Cavanagh et al., 2017). Clinicians in particular appear at risk to assume that aversive childhood experiences explain ODD, even if symptoms of post-traumatic stress disorder are not present (Becker-Haimes et al., 2023). The science that is needed moving forward will not make a priori assumptions favoring a particular etiological or ontological explanation of youth psychopathology (Burke et al., 2022).

Another pitfall we wish to avoid is the unwarranted reification of existing categories and the advancement of untested presumptions about this particular landscape. For example, historic confounding in measures related to this area (e.g., an item such as “I got angry and hit something”) do not provide sufficient clarity to probe whether, in reality, getting angry and hitting may include one without the other. Study designs should also be developed at the construct level so as to characterize any distinctions between affective experiences and disruptive behaviors—or indeed to confirm that there are none. The reality could ultimately be that there is no utility to distinguishing any “splits” within the “lump” of externalizing behavior, but these determinations should be made based on empirical probing rather than a priori assumptions.

Like the far side of the moon, studying the far side of disruptive behavior may seem challenging, and it is not how we are accustomed to looking at things. But, in our view, the promise and possibilities are worth the effort.

Zooming In: The Case of Chronic Irritability

In this section, we explore the implications of the “far side” by adjusting our telescopic lens to zoom in on some particular regions of craters, crags, and stretches of smooth regolith in the example of chronic irritability; then, in the following section, we zoom out to survey the near and far sides of externalizing problems amidst the larger system including internalizing problems and other neighboring bodies.

Although recent work has begun to shed light on different facets of the affective side of disruptive behavior, the developments have stirred up some amount of controversy and disconnect as we have struggled to find agreement regarding what we are looking at. In particular, the increased attention on irritability has evolved along two tracks, one focusing on chronic irritability as a dimension of ODD symptoms (Burke et al., 2021), and another focusing on chronic irritability as a syndrome of mood dysregulation to show its distinctiveness from bipolar disorder (Leibenluft, 2011). These, in turn, led to nosological formulations, ODD with chronic irritability in ICD-11 (Evans et al., 2017) and Disruptive Mood Dysregulation Disorder (DMDD) in DSM-5 (Roy et al., 2014). These developments have met with some criticism (e.g., Axelson et al., 2011; Fristad, 2021) and continue to pose open questions that will need to be resolved in future diagnostic classification systems (Leibenluft et al., 2024).

Of note, DSM-5 classified chronic irritability as a depressive disorder (DMDD), highlighting its mood-related features and making it diagnostically exclusive from ODD. In contrast, ICD-11 classified chronic irritability as a dimension of ODD, a disruptive behavior disorder. Clinical care for DMDD (as a depressive disorder) has been linked to increased prescription of antidepressants and other off-label medications to youth (Findling et al., 2022), while other research (e.g., Kircanski et al., 2018) has focused on irritability’s associations with anxiety. Indeed, longitudinal studies and meta-analyses clearly show that chronic irritability predicts both internalizing and externalizing problems across development (Finlay-Jones et al., 2024; Vidal-Ribas et al., 2016). Clinically, however, the picture may be less clear. For example, one study found that when irritability was identified as a “top problem” among treatment-referred youths, it was distinctly associated with higher anger, dysregulation, and externalizing problems, but not with internalizing problems (Evans et al., 2023). Indeed, clinical presentations of chronic irritability appear to be empirically and phenomenologically aligned with the externalizing spectrum (Evans et al., 2017), defined by frustration, anger, and aggression (Brotman et al., 2017), and characterized by an approach response rather than the withdrawal response that characterizes anxiety and depression (Vidal-Ribas et al., 2016). Hence, it seems reasonable to think about chronic irritability as part of the affective side of disruptive behavior.

According to this view, chronic irritability and disruptive behaviors (at least certain variations of them) could be said to be two sides of the same phenomenon. Thus, it arguably does not make sense to instantiate chronic irritability as a new, freestanding diagnostic entity, as was done with DMDD (Fristad, 2021). More than 10 years after DMDD was introduced, the first-line treatment recommendation continues to be psychosocial intervention, particularly behavioral parent training and cognitive-behavioral program (Evans et al., 2023; Kalvin et al., 2024; Leibenluft et al., 2024; Waxmonsky et al., 2021)—very much like the treatment approaches that would be used for ODD, anger, and aggression (Kaminski & Claussen, 2017; Sukhodolsky et al., 2016)—while specific medications are advised only in specific clinical circumstances, with caution, and in combination with or following after psychosocial intervention (Leibenluft et al., 2024; Orsolini et al., 2024; Vaudreuil et al., 2021).

If continued scientific exploration confirms that chronic irritability manifests clinically and responds to treatment in ways that are consistent with disruptive behavior disorders, then it seems reasonable that chronic irritability would be mapped in the externalizing terrain: the affective side of disruptive behavior. But, to adjust our telescope lens again, this special issue was not intended to focus on irritability specifically. Nor are we arguing that irritability should be considered exclusively from an externalizing perspective. There is value in pursuing this important work from a variety of perspectives, disciplines, and methods. What seems needed now is an integration of these diverse threads of research. Accordingly, the goal of this issue is to serve as a forum to help piece together a more complete picture of the affective side of disruptive behavior. In service of this goal, it is helpful to zoom out and consider irritability, negative affect, and disruptive in the broader context of externalizing and internalizing psychopathology.

Zooming Out: Internalizing and Externalizing Psychopathology

As the preceding section illustrates, one of the intriguing and challenging aspects of irritability is that it appears to lie at the intersection of internalizing and externalizing psychopathology. This vantage point warrants some attention. The existence of higher-order internalizing and externalizing symptom dimensions (Table 1) is one of the most enduring findings in psychopathology research (Achenbach, 2020; Kotov et al., 2021). Externalizing problems comprise a heterogenous set of features (e.g., hitting others, annoying others, staying out past curfew, being notably loud and messy). The externalizing dimension is reliably found to be empirically distinct from (though correlated with) an internalizing dimension, which includes symptoms of depressive and anxiety disorders (Achenbach, 2020; Kotov et al., 2021). This framework has permeated nearly all aspects of research, assessment, intervention, prevention, services, training, and specialization in youth mental health. Much of JCCAP’s contents are organized thusly, according to internalizing interests (e.g., Weersing et al., 2017) or externalizing interests (Kaminski & Claussen, 2017). This organization makes sense; it reflects the advances seen in science in practice, while facilitating further advances. When research institutions (journals, funding agencies, societies, training programs, clinics, etc.) share a common framework of the problems laying before them, this can help facilitate a research agenda for “normal science” in youth mental health (Sonuga‐Barke, 2020, referencing Thomas Kuhn).

However, if misconstrued or overstated, the internalizing-externalizing dichotomy poses challenges for the affective side of disruptive behavior and for youth mental health research more broadly. For example, the term “emotional disorders” is sometimes used to identify internalizing conditions, anxiety and depressive disorders. A potential misinterpretation of this nomenclature is that internalizing problems (perhaps only these problems) are emotional, not behavioral, in nature; and conversely, that externalizing problems (perhaps only these problems) are behavioral, not emotional, in nature. Of course, this is not the case. Anxiety and depressive disorders, while partly characterized by emotional markers, are also defined by behavioral markers, such as avoidance and withdrawal, and effectively treated with behavioral strategies, like exposure and behavioral activation. Likewise, externalizing forms of psychopathology, such as ODD, CD, and ADHD, while most saliently represented by disruptive behaviors (the near side), are also defined by intense negative affect (e.g., irritability, anger). Even if not taken to these semantic extremes, the convention of using emotional interchangeably with internalizing, and behavioral with externalizing, could lead the scientific exploration of externalizing problems to continue to emphasize the near side and to deemphasize, disregard, or misidentify the far side.

The internalizing-externalizing typology provides a useful reminder that nosology is descriptive in nature. Rather than characterizing the “true” nature of problem in an ontological sense, these concepts simply capture patterns of covariation in behavior, affect, and symptoms as seen from the perspective of one or more individuals. While the goal of any classification is to model the real world, it is also true that any such model is a poor representation of the real world. As statistician George Box said, “all models are wrong, but some are useful.” Similarly for mental health, nosological models will intrinsically bear a poor correspondence to reality, and they require ongoing examination and revision. But they are useful in application. Clinically, the goal of diagnoses should be to describe problems, not to categorize people. Accordingly, the science required to explore the affective side of behavioral disorders must be strong, flexible, and driven by a value of improving the lives of those suffering due to these phenomena.

A related challenge is that of comorbidity in internalizing and externalizing problems. The “rule of halves” suggests that among children with any one disorder, approximately one-half have two disorders, of which approximately one-half have a third, and so on (Caspi & Moffitt, 2018). Regardless of whether one adopts a categorical or dimensional perspective, individuals with an externalizing problem are also likely to experience an internalizing problem, and vice versa. In their review of the literature, Achenbach et al. (2016, p. 651), concluded that internalizing and externalizing problems are typically highly correlated with one another, at correlations of around 0.45 to 0.54 in clinical and community samples. Thus, a strict bifurcation of these conceptual dimensions does not reflect empirical, clinical, or public health realities. By this logic, occurrences of comorbidity should not be especially remarkable, nor an indictment of the model itself. Rather, comorbidities provide useful information about (a) how problems show up for people in the real world, in a way that can aid in addressing those problems; and (b) where to consider making potential refinements to the model.

Within the realm of externalizing problems, the history of research has focused in proportion to the scope or severity of manifest behavioral aspects and consequences of CD and ADHD. Location-bound observers could see their obvious features (e.g., hyperactive behaviors, aggression) of the visible face of the landscape. Some less conspicuous features required a closer look to help observers look past preconceptions. The idea, for example, of “capturing the fledgling psychopath in a nomological net” (Lynam, 1997) may seem unduly hyperbolic nowadays. But these were pioneering early missions that increased the salience of these features for many who would not otherwise see them. The subsequent accumulation of a substantial body of evidence (e.g., Frick et al., 2014) demonstrated the useful clarity of limited prosocial emotions and allowed for debates about whether and how features of psychopathy should be organized (e.g., Salekin, 2017). Only more recently has attention been given to the affective aspects of ODD and CD. In light of the context and history described above, affective elements tend to be viewed from a secondary or epiphenomenal perspective (e.g., Cavanagh et al., 2017). Likewise, DMDD exemplifies this in that the affective component of chronic irritability is suggested to exist entirely separately from the behavioral component of ODD.

Finally, advancing science in this area will have to surmount the inherent human problem of reification in prevailing thoughts. As human beings, we cannot help but perceive a man in the moon or a face on Mars. It often takes someone pointing out different features or being shown a similar picture with different lighting. Similarly, mental health nosologies are heavily influenced by their temporal context, and the viewing and description of these phenomena are the products of humans. The presence of circularity in description and measurement can be easily overlooked. For example, even in describing the origins of the internalizing-externalizing framework, Achenbach (1966, p. 4) noted:

[t]he psychiatrists constructing the rating scales as well as those making the symptom ratings were likely to have been trained to expect certain symptoms to occur in the presence of certain other symptoms and to be more alert to the occurrence of symptoms which coincided with the categories to which they were accustomed.

Indeed, looking at the statistical products of the work and the resultant internalizing-externalizing organization, one could easily lose sight of the point of Achenbach’s quote above. The source material being fed into the factor models came from psychiatric records. Those records were the product of human beings who were naturally heavily influenced by the expectations and beliefs about what should and should not be considered among the landscape they were measuring. To avoid being fooled by our biases, to sidestep pulls toward a reification of our expectations, we have to thoughtfully use science

In sum, the historical separation of internalizing and externalizing problems has shown marked and highly laudable utility. The value of this framework in description and translation to real-world improvements is clear. On the other hand, it has arguably contributed to the view of externalizing presentations as behavioral in ways that have obscured the emotional elements of those phenomena. But this may be changing. As discussed below, and as illustrated by this special issue, research groups are now doing exciting and productive work on certain types of affective disturbance (e.g., irritability, anger, aggression, and dysregulation) within the youth externalizing spectrum. It is critical that this work collectively probes, prods and pushes from within and outside of existing ontological, clinical, and measurement expectations to the extent possible. These papers engage with important questions of measurement, theoretical definition, and nomothetical organization, with important implications for the utility and validity of varying representations of affective difficulties in the externalizing context.

Need for the Special Issue

Substantial efforts have been made to elucidate the affective side of disruptive behavior problems. To focus on only journal collections, more than a dozen special issues, sections, and collections have crossed our radar in the years leading up to and during the preparation of this volume. See Table 3 for an incomplete list. Although an adequate summary is beyond the scope of this article, it is worth emphasizing that many of these efforts have led to changes in the domains of diagnosis, measurement, and classification of psychopathology. Established categories like ODD and CD and ADHD are now accompanied by problems like DMDD in DSM-5 (Roy et al., 2014) and by a subtype for ODD with chronic irritability-anger in ICD-11 (Evans et al., 2017). Further initiatives are currently underway, such as a new diagnostic code for explosive emotional outbursts (Carlson et al., 2023) and an empirically derived construct for impulsive/reactive aggression (AIR) for clinical research (Stepanova et al., 2023).

Table 3. Recent special collections related to youth irritability, anger, and aggression.

Relevant Citation	Journal	Topic	Type
Drabick and Kendall (2010)	Clinical Psychology: Science & Practice	Youth mental health comorbidity	Issue
Stringaris et al. (2012)	Journal of Child Psychology and Psychiatry	Mood dysregulation	Issue
Carlson (2016)	Journal of Child and Adolescent Psychopharmacology	Disruptive mood dysregulation disorder	Issue
Beauchaine and Cicchetti (2019)	Development and Psychopathology	Emotion dysregulation	Issue
Roy and Comer (2020)	Behavior Therapy	Pediatric irritability	Issue
Dalgleish et al. (2020)	Journal of Consulting and Clinical Psychology	Transdiagnostic approaches	Section
Moehler et al. (2022)	Frontiers in Psychiatry	Emotion dysregulation	Series
Carlson et al. (2021) and Singh and Carlson (2021)	Child and Adolescent Psychiatric Clinics of North America	Dysregulation and outbursts	Issue (x2)
Carlson et al. (2023) (edited by Dickstein, Althoff, & Novins)	Journal of the American Academy of Child & Adolescent Psychiatry	Reviews related to youth emotion dysregulation	Series
Wiggins et al. (2023)	International Journal of Research in Psychiatric Methods	Measurement of affective dimensions of behavior	Issue
Forbes et al. (2023)	Journal of Psychopathology and Clinical Science	Symptoms, signs, and mechanisms of psychopathology	Section
Findling et al. (2023)	JAACAP Open	Aggressive behavior	Series
Zheng and Goulter (2024)	Research on Child and Adolescent Psychopathology	Intensive longitudinal studies of externalizing psychopathology	Issue

All such efforts face a familiar challenge that Hyman (2011) referred to as “repairing a plane while it is flying” (p. 11). In other words, as recognition of emotion in disruptive behavior grows, the options for advancing science and practice in this area can only be pursued (or repaired) in the context of existing frameworks that have largely focused on the behavioral manifestations of externalizing problems, with less attention to affect. Of course, diagnostic categories are only one type of framework, and there is value in pursuing this work from a dimensional non-diagnostic (or transdiagnostic) perspective. The simultaneously dimensional and categorical nature of psychopathology has long been appreciated (Rutter, 2011); it also aligns with current initiatives like RDOC (Cuthbert & Insel, 2013) and HITOP (Kotov et al., 2021)—not as a replacement to diagnoses, but as complementary frameworks, serving different purposes, and collectively pushing clinical science forward (Beauchaine & Hinshaw, 2020; Clark et al., 2017). Taken together, these developments suggest there is unlikely any single framework that will clearly and completely elucidate the affective side of disruptive behavior. Instead, different frameworks contribute different values and strengths. The challenge facing us now is to adopt a broad, inclusive, and cross-cutting approach that weaves together different frameworks and threads of evidence to move clinical science forward.

For example, to define and measure irritability is to rely heavily upon closely related concepts like anger and aggression, which in turn require their own overlapping definitions and measurements (Evans et al., 2024, this issue). As clinical symptoms, these problems are distinct yet related, clustering together as overt externalizing problems (Frick et al., 1993) while also cropping up in more than a dozen other mental disorder categories (Evans et al., 2023). This is a fundamental challenge to defining the affective side of disruptive behavior: it is difficult to characterize any one of these constructs without invoking the others. Clearly, there is work to be done to better conceptualize, measure, and model these phenomena while also acknowledging the similarities and differences among them. Accordingly, this special issue was conceptualized broadly, based on phenomenology rather than terminology, to cover irritability, anger, and aggression, as well as related diagnostic constructs like ODD, CD, and DMDD.

Considering the literature reviewed above, we hope that the need for this special issue is now clear. The explosion of research on topics related to the affective side of disruptive behavior now makes integration and synthesis necessary in order to move forward. Much of the relevant research has been carried out with a rather circumscribed focus on a particular category or construct (e.g., ODD, ADHD, DMDD, reactive aggression, anger). While prior special issues are relevant (Table 3), they have tended to focus on one particular problem (e.g., irritability, outbursts, DMDD), contributing more to the depth of understanding on a specific topic and highlighting the need for further bridging across topics.

The various topics in this space appear to stem, at least in part, from work occurring across different disciplines, methodological approaches, and substantive backgrounds. Moreover, the natural evolution of research tends to involve more splitting (digging deeper into variable of interest) and less lumping (integrative work to bridge gaps across variables). In certain respects, then, the present questions are not surprising; they may be positive signs reflecting scientific progress. But in other respects, youths and families are likely better served when youth mental health clinicians and research work together to tackle the hard problems families face—which generally do not fall into the specialized bins that characterize our research. Thus, it seems that an integrative look at the affective side of disruptive behaviors could help foster advances in research and practice. We hope that the current special issue helps achieve this goal.

Overview of Special Issue Articles

The current issue compiles a diverse collection of new research investigating affect, emotion, and mood in the context of youth disruptive behavior problems. Its contributions were invited to not merely arrange different studies on closely related phenomena alongside each other, but rather to tackle issues of overlap head-on, in the interest of resolving some of the major boundaries and conceptual challenges facing the field. As summarized in Table 4, these submissions are broadly organized to provide balanced coverage of developmental psychopathology perspectives (4 empirical articles) and applied assessment/treatment perspectives (4 empirical articles and 1 evidence base update review article), and 2 future directions review articles. Below we discuss each of these articles in turn.

Table 4. Overview of the 12 articles included in the special issue.

Citation	Article type	Classification	Summary of major finding
Present article	Introduction/review	Integrative	Introduction and orientation to special issue.
Silver et al. (2024)	Original empirical	Psychopathology, longitudinal	Irritability may not be a facet of temperament, but rather shows distinct associations with effortful control, disinhibition, and negative affect from early childhood to adolescence.
Shields et al. (2024)	Original empirical	Psychopathology, phenomenological	Reactive aggression was linked to multiple forms of negative emotionality, whereas instrumental aggression was linked to higher callous-unemotional traits and lower positive emotions.
Perhamus et al. (2024)	Original empirical	Psychopathology, longitudinal	In a multi-informant school sample, irritability predicted higher physical and relational aggression at a between-person level, but there were no associations at a within-person level.
Derella et al. (2024)	Original empirical	Psychopathology, phenomenological	During behavioral frustration, children with chronic irritability showed greater persisting frustration and inhibitory control difficulties, partly linked to co-occurring psychopathology.
Ferrara et al. (2024)	Original empirical	Applied/clinical, assessment	Findings support the novel Frustration Social Stressor for Adolescents (FSS-A) for assessing adolescents’ frustration in terms of state anger, anxiety, and cortisol response.
Evans et al. (2024)	Evidence base update review	Applied/clinical, assessment	This systematic review summarizes the evidence behind 68 instruments for measuring irritability, anger, and/or aggression in children and adolescents via self- or proxy-report.
Wakschlag et al. (2024)	Original empirical	Applied/clinical, assessment	Using early irritability and adverse childhood experiences, demographics, a risk calculator predicted which youths are likely to develop future internalizing and externalizing disorders.
Parent et al. (2024)	Original empirical	Applied/clinical, intervention	In a behavioral parent training randomized trial, technology enhancements led to greater improvements for children with externalizing and co-occurring internalizing symptoms.
Naim et al. (2024)	Original empirical	Applied/clinical, intervention	A multiple-baseline trial of a novel cognitive-behavioral therapy for youths with severe irritability provided initial support for the intervention’s acceptability, feasibility, and efficacy.
Carlson et al. (2024)	Future directions review	Integrative	Authors provide specific recommendations for the field to advance understanding, measurement, and care for two distinct but closely related problems: irritable mood and outbursts.
Lahey (2024)	Future directions review	Integrative	A limited set of dispositions (negative emotionality, prosociality, daring), orthogonal to psychopathology, can help shed light on the causes of internalizing and externalizing problems broadly.

Note: See References section for the full citations. Classification is a rough grouping assigned by the editors to provide some organization.

On the affective side of disruptive behavior, basic questions of phenomenology and conceptualization persist. For example, it seems reasonable to ask: Is irritability just negative affect? Silver et al. (2024) analyzed longitudinal data to investigate this question. Although irritability was correlated with negative affect cross-sectionally and longitudinally, irritability appeared to be a distinct phenomenon, independent from negative affect, with distinct patterns of associations with broader regulatory variables (e.g., effortful control, disinhibition) from early childhood through adolescence.

Turning to aggression, Shields et al. (2024) found that 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. And while these results indicate that different functions of aggression are linked to different patterns of affect, other analyses simultaneously underscore the importance of overall aggression and the high correlation between the proactive and reactive types. In another study focused on the alternative typology of relational vs. physical aggression, Perhamus et al. (2024) leveraged a large, three-wave, multi-informant school sample. At a between-person level, youths with higher irritability tended to have persistently higher physical aggression and initially higher relational aggression, but no within-person effects were detected. Taken together, these two studies highlight distinct and common aspects of dimensions of aggression, all bearing some association to irritability.

Two studies in the special issue leverage the strengths of direct behavioral paradigms. First, on the phenomenology side, Derella et al. (2024) had children with and without chronic irritability complete frustrative go/no-go and mirror tracing persistence tasks. Notably, the children with chronic irritability did not demonstrate more intense frustration during either task, but they showed persisting frustration and inhibitory control difficulties afterward, which appeared to be driven by the subgroup with chronic irritability and ADHD. Second, from the assessment side, Ferrara et al. (2024) used the Frustration Social Stressor for Adolescents (FSS-A) to examine youths’ psychological and physiological responses to frustration. Results provided support for the FSS-A and showed that irritability was associated with increased state anger before and during frustrating social interactions.

Moving to rating scales and questionnaires, Evans et al. (2024) conducted a systematic review of self- or proxy-report measures focused on irritability, anger, and/or aggression in youth. The result was 68 instruments, characterized in terms of strength of psychometric evidence and descriptive information. But these tools only scratch the surface of what could be done with them. For example, Wakschlag et al. (2024) built a risk calculator that demonstrates proof of principle. Using only measures of early irritability, adverse childhood experiences, and demographics, these authors predicted predicted which preschoolers would likely to develop internalizing or externalizing disorders by preadolescence.

Two studies in the special issue report new empirical results concerning the treatment of youth on the affective side of disruptive behavior problems. First, Parent et al. (2024) drew from a randomized controlled trial of behavioral parent training with vs. without a technology-enhanced component to test a question at the internalizing/externalizing divide. Their results showed that technology enhancements led to greater improvements, compared to standard parent training, in positive parenting and child compliance for children with co-occurring internalizing and externalizing symptoms, speaking to the promise of established treatments, personalization, and technological enhancements. Second, Naim et al. (2024) publish the first results from a multiple-baseline trial testing a novel therapy for irritability involving exposure-based cognitive-behavioral techniques with integrated parent management skills. Results provided initial support for the intervention’s acceptability, feasibility, and preliminary efficacy, laying the groundwork for future tests of effectiveness and mechanisms.

Finally, we are fortunate to include two invited Future Directions articles in this collection. First, the piece by Carlson et al. (2024) provides several specific recommendations for the field to advance understanding, measurement, and care for two distinct but closely related problems: irritable mood and outbursts. Second, Lahey (2024) zooms back out to internalizing and externalizing problems broadly, showing that a limited set of dispositions (negative emotionality, prosociality, daring), orthogonal to psychopathology, can help shed light on etiology. It is our hope that these Future Directions articles can enrich conceptualizations of the affective side of disruptive behavior at the critical intersections of internalizing and externalizing, emotional and behavioral, broad and narrow, basic and applied.

Conclusion

Having charted the salient behaviors on the near side of externalizing psychopathology, the field is currently sending back sharper images of the intense negative affect that lies on the far side. However, this less familiar landscape side remains distant. And all sides of the phenomenon are obscured by shadows that overtake it at regular intervals. Despite all the progress made since those early beliefs of past centuries, it is still not clear how these modern images should be pieced together to form a more definitive model of youth psychopathology. Until that picture comes into better focus, the mission remains as clear as ever: to advance knowledge and practice, through science, for the benefit of youth and families.

Acknowledgments

We thank the researchers who contributed their time and efforts to the special issue as authors and reviewers.

Disclosure Statement

No potential conflict of interest was reported by the author(s).

Data Availability Statement

This is a review paper that has no data associated with it.

Additional information

Funding

This project was not specifically associated with any source of funding.

Notes

¹ Throughout this paper, we generally use the terms “disruptive behavior” and “externalizing” interchangeably, although different connotations and contexts are explored (e.g., their relations to “emotional” and “internalizing,” respectively). See Table 1 for corresponding broadband distinctions that have been used over the years.

² While disruptive behavior disorders are amongst the most prevalent disorders in clinic populations, it is also the case that most individuals with these disorders never engage in treatment. While these features demand attention, prevailing beliefs and expectations about them may negative influence identification, referral and treatment-seeking.

³ The example of externalizing problems being misconstrued as masked depression in youth parallels the more recent example of chronic irritability being misconstrued by some clinicians as pediatric bipolar disorder, an occurrence that contributed to the acceleration of research on youth irritability generally (Leibenluft, 2011).