Do we need an irritable subtype of ADHD? Replication and extension of a promising temperament profile approach to ADHD subtyping

Longitudinal network model of the co-development of temperament, executive functioning, and psychopathology symptoms in youth with and without ADHD

Attention-deficit hyperactivity disorder (ADHD) is a common, chronic, and impairing disorder, yet presentations of ADHD and clinical course are highly heterogeneous. Despite substantial research efforts, both (a) the secondary co-occurrence of ADHD and complicating additional clinical problems and (b) the developmental pathways leading toward or away from recovery through adolescence remain poorly understood. Resolving these requires accounting for transactional influences of a large number of features across development. Here, we applied a longitudinal cross-lagged panel network model to a multimodal, multilevel dataset in a well-characterized sample of 488 children (nADHD = 296) to test Research Domain Criteria initiative-inspired hypotheses about transdiagnostic risk. Network features included Diagnostic and Statistical Manual of Mental Disorders symptoms, trait-based ratings of emotional functioning (temperament), and performance-based measures of cognition. Results confirmed that ADHD symptom domains, temperamental irritability, and working memory are independent transdiagnostic risk factors for psychopathology based on their direct associations with other features across time. ADHD symptoms and working memory each had direct, independent associations with depression. Results also demonstrated tightly linked co-development of ADHD symptoms and temperamental irritability, consistent with the possibility that this type of anger dysregulation is a core feature that is co-expressed as part of the ADHD phenotype for some children.

Using ecological momentary assessment to enhance irritability phenotyping in a transdiagnostic sample of youth

Irritability is a transdiagnostic symptom dimension in developmental psychopathology, closely related to the Research Domain Criteria (RDoC) construct of frustrative nonreward. Consistent with the RDoC framework and calls for transdiagnostic, developmentally-sensitive assessment methods, we report data from a smartphone-based, naturalistic ecological momentary assessment (EMA) study of irritability. We assessed 109 children and adolescents (Mage = 12.55 years; 75.20% male) encompassing several diagnostic groups – disruptive mood dysregulation disorder (DMDD), attention-deficit/hyperactivity disorder (ADHD), anxiety disorders (ANX), healthy volunteers (HV). The participants rated symptoms three times per day for 1 week. Compliance with the EMA protocol was high. As tested using multilevel modeling, EMA ratings of irritability were strongly and consistently associated with in-clinic, gold-standard measures of irritability. Further, EMA ratings of irritability were significantly related to subjective frustration during a laboratory task eliciting frustrative nonreward. Irritability levels exhibited an expected graduated pattern across diagnostic groups, and the different EMA items measuring irritability were significantly associated with one another within all groups, supporting the transdiagnostic phenomenology of irritability. Additional analyses utilized EMA ratings of anxiety as a comparison with respect to convergent validity and transdiagnostic phenomenology. The results support new measurement tools that can be used in future studies of irritability and frustrative nonreward.

Phasic Versus Tonic Irritability: Differential Associations With Attention-Deficit/Hyperactivity Disorder Symptoms

OBJECTIVE

Irritability is a multifaceted construct in pediatric psychopathology. It has been conceptualized as having a phasic dimension and a tonic dimension. Disruptive mood dysregulation disorder is defined by the presence of both dimensions. Severe irritability, or disruptive mood dysregulation disorder, is highly comorbid with attention-deficit/hyperactivity disorder (ADHD). However, it is unknown whether the presence of ADHD modulates the expression of phasic and tonic irritability.

METHOD

A data-driven, latent variable approach was used to examine irritability and ADHD symptoms in a transdiagnostic pediatric sample (N = 489) with primary disruptive mood dysregulation disorder, ADHD, subclinical irritability symptoms, or no diagnosis. Using latent profile analyses, we identified 4 classes: high levels of both irritability and ADHD symptoms, high levels of irritability and moderate levels of ADHD symptoms, moderate levels of irritability and high levels of ADHD symptoms, and low levels of both irritability and ADHD symptoms. Confirmatory factor analysis operationalized phasic irritability and tonic irritability.

RESULTS

As expected, the 2 latent classes characterized by high overall irritability exhibited the highest levels of both phasic and tonic irritability. However, between these 2 high irritability classes, highly comorbid ADHD symptoms were associated with significantly greater phasic irritability than were moderately comorbid ADHD symptoms. In contrast, the 2 high irritability groups did not differ on levels of tonic irritability.

CONCLUSION

These findings suggest that phasic, but not tonic, irritability has a significant association with ADHD symptoms and that phasic and tonic might be distinct, though highly related, irritability dimensions. Future research should investigate potential mechanisms underlying this differential association.

Irritability in developmental age: A narrative review of a dimension crossing paediatric psychopathology

OBJECTIVE

Irritability is an important theme in paediatric psychiatry considering its high frequency in developmental age, its association with negative outcomes and consequently significant public health impact. Present as main or associated feature of several psychiatric diagnoses, irritability represents a challenge for clinicians who try to understand its origin and role in developmental psychopathology. In this review we try to: (1) get an overview of this dimension and its relationship with each of the main neuropsychiatric disorders in paediatric population and (2) provide a summary of currently available instruments to assess irritability in children and adolescents.

METHOD

In this narrative review, an overview of irritability in children and adolescents is proposed focusing on selected literature.

RESULTS

Irritability as feature of many paediatric psychiatric conditions has been evaluated by many authors and included in classifications of paediatric psychiatric diseases. Framework of irritability evolved over time and dimension of irritability has been investigated using different tools and methodologies, both qualitative and quantitative. Metrics of irritability as clinical dimension are important in the diagnostic process of paediatric diseases.

CONCLUSION

Investigating the presence of irritability in all children with related disorders is mandatory if we consider the risk for functional impairment and affective and behavioural disorders associated with high levels of irritability. Using rigid threshold in developmental age to differentiate physiological from pathological irritability could lead many children having subthreshold levels of irritability to receive no diagnosis and, consequently, no treatment where instead a dimensional approach to irritability could allow to identify prodromal phase and prevent the evolution towards clinical pathological expressions.

Treatment Response among Preschoolers with Disruptive Behavior Disorders: The Role of Temperament and Parenting

Objective: This study examined associations between temperament (negative affect, effortful control, and surgency) and symptoms of attention-deficit/hyperactivity disorder (ADHD) and oppositional defiant disorder (ODD) within a diverse preschool sample. Interactions between temperament and parenting in the prediction of ADHD/ODD symptoms before and after an 8-week early intervention program (i.e., Summer Treatment Program for Pre-kindergartners; STP-PreK) were also examined.Method: The sample included 215 children (Mage = 5.0, 80.9% male, 84.7% Latinx) with a diagnosis of ADHD and/or ODD who completed the STP-PreK. Temperament was measured via parent report while ADHD/ODD symptoms were assessed via combination of parent and teacher report. Positive and negative parenting were assessed via rating scales and a standardized parent-child interaction observation.Results: Higher surgency was associated with greater symptom severity of ADHD/ODD pre- and post-treatment. Higher negative affect was associated with greater symptom severity of ODD pre- and post-treatment, while higher effortful control was only associated with lower symptom severity of inattention pre-treatment. Positive parenting predicted lower symptom severity of ADHD/ODD post-treatment. Moderation analyses indicated that the benefits of low levels of negative parenting only occurred when paired with low temperament risk for symptoms of hyperactivity and ODD. Additionally, only the combination of high surgency and high observed negative parenting resulted in greater symptom severity of ODD. Finally, decreases in inconsistent discipline predicted decreases across all symptom domains post-treatment.Conclusions: Our findings add to the temperament-based model of ADHD/ODD by highlighting temperament's unique prediction of treatment response as well as important interactions with the caregiving environment.

Temperament Traits Mark Liability for Coexisting Psychiatric Symptoms in Children With Elevated ADHD Symptoms

Objective: Among children with ADHD, coexisting psychiatric disorders are common and associated with greater impairment and symptom persistence. Given that temperament traits are easily measured, developmentally stable, and variable among youth with ADHD, temperament profiles may be clinically useful for predicting liability for coexisting psychiatric symptoms in this population. Methods: Eighty-three children with ADHD symptoms participated. Caregivers rated their child's surgency, negative emotionality, and effortful control, as well as severity of internalizing and externalizing psychiatric symptoms. Hierarchical linear regressions were conducted to estimate associations between temperament traits and psychiatric symptoms, controlling for severity of ADHD. Results: Temperament ratings explained significant variance in psychiatric symptoms above and beyond ADHD symptoms alone. Symptoms of each coexisting psychiatric disorder was associated with a distinct temperament and ADHD symptom profile. Conclusion: Temperament ratings appear to have clinical utility for predicting coexisting psychiatric symptoms in children with elevated ADHD symptoms.

Structural Equation Modeling (SEM): Childhood Aggression and Irritable ADHD Associated with Parental Psychiatric Symptoms

Background: Children with attention deficit hyperactivity disorder (ADHD) co-occurring with Oppositional Defiant Disorder (ODD) further present aggressive behavior and may have a depressive parent. A child with co-occurring ADHD and ODD has differentially higher levels of behavioral and emotional difficulties. Little is known about how the irritable subtype of ADHD in children mediates the development of parental symptomatology. This study aims to elucidate the direct or indirect influence of childhood disruptive ADHD with aggressive behavior on their parental symptom using Structural Equation Modeling (SEM). Methods: A total of 231 ADHD children and their parents completed the Swanson, Nolan, and Pelham Version IV questionnaire for symptoms of ADHD, Oppositional Defiant Disorder (ODD) scale for irritable symptoms, Child Behavior Check List (CBCL) for aggression, and Symptom Checklist (SCL) for parental symptom. Results: The three-factor confirmatory factor analysis (CFA) model found symptoms of inattention, hyperactivity/impulsivity, irritable ODD, and aggression were inter-related. Mediational analyses demonstrated ODD mediates symptoms directly predicting the risk of increasing ADHD severity. Disruptive child symptoms (ADHD + ODD + aggression) may increase the risk of depression-related symptoms in the parent. When the child’s aggression increases by one standard deviation (SD), parental psychiatric symptoms increase by 0.235 SD (p < 0.001). Conclusions: By this SEM pathway analysis, there is the correlation between the disruptive, more aggressive subtype of ADHD in children/adolescents and the existence of psychopathological symptomatology of their parents. ADHD + ODD + aggression in children should be classified as an irritable subtype of ADHD, warranting early diagnosis and intensive treatment.

Increased pupil dilation to happy faces in children with hyperactive/impulsive symptoms of ADHD

Attention-deficit/hyperactivity disorder (ADHD) is associated with disrupted emotional processes including impaired regulation of approach behavior and positive affect, irritability, and anger. Enhanced reactivity to emotional cues may be an underlying process. Pupil dilation is an indirect index of arousal, modulated by the autonomic nervous system and activity in the locus coeruleus-noradrenergic system. In the current study, pupil dilation was recorded while 8- to 12- year old children (n = 71, 26 with a diagnosis of ADHD and 45 typically developing), viewed images of emotional faces. Parent-rated hyperactive/impulsive symptoms were uniquely linked to higher pupil dilation to happy, but not fearful, angry, or neutral faces. This was not explained by comorbid externalizing symptoms. Together, these results suggest that hyperactive/impulsive symptoms are associated with hyperresponsiveness to approach-related emotional cues across a wide range of symptom severity.

Deriving within-person estimates of delta-beta coupling: A novel measure for identifying individual differences in emotion and neural function in childhood

Delta-beta coupling is increasingly used to understand early emotional development. However, little is known about the development of the coupling, limiting its utility for identifying normative or aberrant functioning. We used a prospective longitudinal sample (N = 122) to compare measures of within-person and between-person coupling between ages 3 and 5, track the developmental trajectory of coupling, identify individual differences in patterns of development, and explore emotion-related predictors and outcomes of discrete developmental patterns. Within-person measures, limited in overall utility, were most useful when (1) statistical approaches produced more homogenous groups within the overall sample (extreme groups or latent classes) or (2) the full developmental course was considered. We found two trajectories of change in frontal coupling and three trajectories of change in parietal coupling. Coupling trajectories were predicted by observed fear and approach/avoidance at age 3. In addition, high levels of frontal coupling at age 3 that declined and then levelled out through age 5 were associated with lower levels of internalizing by age 5. This work provides a foundation for understanding normative change in delta-beta coupling across the preschool years and useful insight for the use of this metric in future work.

Chronic Irritability in Youth: A Reprise on Challenges and Opportunities Toward Meeting Unmet Clinical Needs

This commentary focuses on irritability, one subtype of emotion dysregulation. We review literature demonstrating that irritability is not a developmental phenotype of bipolar disorder, but is longitudinally associated with unipolar depression and anxiety and genetically associated with unipolar depression, anxiety, and attention-deficit hyperactivity disorder. We describe how irritability is amenable to translational research, in part because of the relevance of frustrative nonreward, a model developed in rodents, to human irritability. Last, we demonstrate how such research has suggested a novel exposure-based intervention for irritability.

Longitudinal attention-deficit/hyperactivity disorder symptom networks in childhood and adolescence: Key symptoms, stability, and predictive validity

The current study visualized attention-deficit/hyperactivity disorder (ADHD) symptom networks in a longitudinal sample of participants across childhood and adolescence with exploratory examination of age and gender effects. Eight hundred thirty-six children ages 7-13 years were followed annually for 8 years in total. Across parent and teacher report, results suggested "is easily distracted" and "difficulties sustaining attention" as central symptoms across three testing points (i.e., Year 1, Year 3, and Years 5-8 collapsed). "Difficulties following instructions" and "intrudes/interrupts" also emerged as parent-reported central symptoms. Assessment of network structure across the three testing points suggested global robustness of relations among ADHD symptoms from midchildhood into early adolescence. However, relations among symptoms that cause problems in school settings (i.e., being easily distracted) were stronger in teacher-reported than parent-reported networks. When aggregated into a sum score, central symptoms during Year 1 predicted total difficulties related to mental health problems 5 years later just as well as all 18 symptoms. Central symptoms of ADHD may be useful as screeners of future emotional and behavioral difficulties. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Rationale and validation of a novel mobile application probing motor inhibition: Proof of concept of CALM-IT

Identification of behavioral mechanisms underlying psychopathology is essential for the development of novel targeted therapeutics. However, this work relies on rigorous, time-intensive, clinic-based laboratory research, making it difficult to translate research paradigms into tools that can be used by clinicians in the community. The broad adoption of smartphone technology provides a promising opportunity to bridge the gap between the mechanisms identified in the laboratory and the clinical interventions targeting them in the community. The goal of the current study is to develop a developmentally appropriate, engaging, novel mobile application called CALM-IT that probes a narrow biologically informed process, inhibitory control. We aim to leverage the rigorous and robust methods traditionally used in laboratory settings to validate this novel mechanism-driven but easily disseminatable tool that can be used by clinicians to probe inhibitory control in the community. The development of CALM-IT has significant implications for the ability to screen for inhibitory control deficits in the community by both clinicians and researchers. By facilitating assessment of inhibitory control outside of the laboratory setting, researchers could have access to larger and more diverse samples. Additionally, in the clinical setting, CALM-IT represents a novel clinical screening measure that could be used to determine personalized courses of treatment based on the presence of inhibitory control deficits.

Is there any incremental benefit to conducting neuroimaging and neurocognitive assessments in the diagnosis of ADHD in young children? A machine learning investigation

Given the negative trajectories of early behavior problems associated with ADHD, early diagnosis is considered critical to enable intervention and treatment. To this end, the current investigation employed machine learning to evaluate the relative predictive value of parent/teacher ratings, behavioral and neural measures of executive function (EF) in predicting ADHD in a sample consisting of 162 young children (ages 4–7, mean age 5.55, 82.6 % Hispanic/Latino). Among the target measures, teacher ratings of EF were the most predictive of ADHD. While a more extensive evaluation of neural measures, such as diffusion-weighted imaging, may provide more information as they relate to the underlying cognitive deficits associated with ADHD, the current study indicates that measures of cortical anatomy obtained in research studies, as well cognitive measures of EF often obtained in routine assessments, have little incremental value in differentiating typically developing children from those diagnosed with ADHD. It is important to note that the overlap between some of the EF questions in the BRIEF, and the ADHD symptoms could be enhancing this effect. Thus, future research evaluating the importance of such measures in predicting children’s functional impairment in academic and social areas would provide additional insight into their contributing role in ADHD.

Is an irritable ADHD profile traceable using personality dimensions? Replicability, stability, and predictive value over time of data-driven profiles

Pediatric attention deficit/hyperactivity disorder (ADHD) is a heterogeneous condition. In particular, children with ADHD display varying profiles of dispositional traits, as assessed through temperament and personality questionnaires. Previous data-driven community detection analyses based on temperament dimensions identified an irritable profile of patients with ADHD, uniquely characterized by elevated emotional dysregulation symptoms. Belonging to this profile increased the risk of developing comorbid disorders. Here, we investigated whether we could replicate this profile in a sample of 178 children with ADHD, using community detection based on personality dimensions. Stability of the identified profiles, of individual classifications, and clinical prediction were longitudinally assessed over a 1-year interval. Three personality profiles were detected: The first two profiles had high levels of neuroticism, with the first displaying higher ADHD severity and lower openness to experience (profile 1; N = 38), and the second lower agreeableness (profile 2; N = 73). The third profile displayed scores closer to the normative range on all five factors (profile 3; N = 67). The identified profiles did only partially replicate the temperament-based profiles previously reported, as higher levels of neuroticism were found in two of the three detected profiles. Nonetheless, despite changes in individual classifications, the profiles themselves were highly stable over time and of clinical predictive value. Whereas children belonging to profiles 1 and 2 benefited from starting medication, children in profile 3 did not. Hence, belonging to an emotionally dysregulated profile at baseline predicted the effect of medication at follow-up over and above initial ADHD symptom severity. This finding suggests that personality profiles could play a role in predicting treatment response in ADHD.

Maternal Parenting and Toddler Temperament: Predictors of Early School Age Attention-Deficit/Hyperactivity Disorder-Related Behaviors

Detection of early risk for developing childhood attention-deficit/hyperactive disorder (ADHD) symptoms, inattention and hyperactivity, may be critical for prevention and early intervention. Temperament and parenting are two promising areas of risk, representing potential targets for preventive intervention; however, studies have rarely tested these factors longitudinally using multiple methods and reporters. In a longitudinal sample of 312 low-income boys, this study tested the hypothesis that negative emotionality (NE) and effortful control (EC) in toddlerhood (1.5-3.5 years old) would predict mother- and teacher-reported ADHD-related behaviors at school age (5-7 years old). Direct effects of observed warm, supportive and harsh maternal parenting were tested in relation to ADHD-related behaviors and as moderators of associations between NE and EC and ADHD-related behaviors. Several predictions were supported: 1) Greater maternal-reported toddler NE positively predicted mother-reported ADHD behaviors; 2) Greater observed EC was associated with fewer mother- and teacher-reported ADHD-related behaviors; 3) Warm, supportive parenting predicted fewer teacher-reported ADHD-related behaviors, and harsh parenting predicted more ADHD-related behaviors as reported by parents and teachers; 4) Harsh parenting moderated the association between observed EC and mother-reported ADHD-related behaviors. Together, the findings suggest that lower child EC, lower warm/supportive parenting, and greater harsh parenting in toddlerhood independently signal increased risk for later ADHD-related behaviors; further, the association between low EC and ADHD-related behaviors was amplified in the context of high levels of harsh parenting.

Irritability Predicts Hyperactive/Impulsive Symptoms Across Adolescence for Females

Irritability is common in Attention-Deficit Hyperactivity Disorder (ADHD), but little is known about whether irritability predicts the course of ADHD symptoms over time. Adolescence is a dynamic period of emotional development as well as shifts in ADHD symptoms; an important goal is to identify youth at risk of increasing or persisting symptoms. We examined irritability as a longitudinal predictor of change in adolescents' ADHD symptoms, as well as how this link may differ in females versus males. The sample included 108 youth (72 males) age 12-16 years (M = 14.21 years, SD = 1.44 years), 62 of whom met criteria for ADHD. Approximately 18 months later, 80 participants (48 males) were followed up at Time 2. A dimensional approach was used to examine changes over time in parent-reported inattentive and hyperactive/impulsive symptoms. Longitudinal path analysis revealed that irritability at Time 1 predicted higher relative hyperactive/impulsive symptoms at Time 2 after controlling for age and longitudinal stability in all variables. A multiple-group analysis examining moderation by sex/gender revealed that this association was significant only for females. These results suggest that irritability may play a key role in the persistence and worsening of hyperactive/impulsive symptoms across adolescence for females, with potential implications for the diagnosis and treatment of females with ADHD.

The Impact of Persistent Irritability on the Medication Treatment of Paediatric Attention Deficit Hyperactivity Disorder

This study compares the efficacy and tolerability of central nervous system (CNS) stimulants in children with attention deficit hyperactivity disorder (ADHD) with and without prominent irritability (IRR) over the course of 30 months. This is a secondary analysis of a study examining growth patterns in medication naïve children with ADHD subsequently treated with CNS stimulants (predominantly OROS-Methylphenidate, up to 54 mg per day) for 30 months. Participants had to meet full diagnostic criteria for ADHD and been treated with CNS stimulants for under 30 days. Children were classified as IRR if they were rated as pretty much or very much on either of the "often angry" or easily annoyed" items plus "lose temper," items of the Disruptive Behavior Disorders Rating Scale (DBDRS). Structured ratings of ADHD symptoms, impairment, side effects, and symptoms of oppositional defiant disorder (ODD) were collected every 2-12 weeks for the duration of the study. Medication use was measured by pill count and parent report. The IRR group comprised 28% of all participants. The IRR group had significantly higher levels of ADHD and ODD symptoms, impairment, and side effects ratings at baseline. In the IRR group, ODD symptoms, emotional lability, and impairment significantly decreased for participants with higher medication use. Total side effects increased for non-IRR participants with higher medication use. Emotional side effects decreased for IRR participants with higher medication use. Central nervous system stimulants were a tolerable and efficacious treatment in treatment naïve youth with ADHD with irritability. Clinical Trials Registration: NCT01109849.

Resolving heterogeneity in transcranial electrical stimulation efficacy for attention deficit hyperactivity disorder

While the treatment of Attention Deficit Hyperactivity Disorder (ADHD) is dominated by pharmacological agents, transcranial electrical stimulation (tES) is gaining attention as an alternative method for treatment. Most current meta-analyses have suggested that tES can improve cognitive functions that are otherwise impaired in ADHD, such as inhibition and working memory, as well as alleviated clinical symptoms. Here we review some of the promising findings in the field of tES. At the same time, we highlight two factors, which hinder the effective application of tES in treating ADHD: 1) the heterogeneity of tES protocols used in different studies; 2) patient profiles influencing responses to tES. We highlight potential solutions for overcoming such limitations, including the use of active machine learning, and provide simulated data to demonstrate how these solutions could also improve the understanding, diagnosis, and treatment of ADHD.

Development of ADHD: Etiology, Heterogeneity, and Early Life Course

ADHD represents a powerful entry point for developmental approaches to psychopathology due to its major role in early emergence of major life problems. One key issue concerns the role of early environmental risks in etiology and maintenance in the context of genetic liability. Here, psychosocial aspects of development need more attention. A second key issue is that phenotypic heterogeneity requires better resolution if actionable causal mechanisms are to be effectively identified. Here, the interplay of cognition and emotion in the context of a temperament lens is one helpful way forward. A third key issue is the poorly understood yet somewhat striking bifurcation of developmental course in adolescence, when a subgroup seem to have largely benign outcomes, while a larger group continue on a problematic path. A final integrative question concerns the most effective conceptualization of the disorder in relation to broader dysregulation. Key scientific priorities are noted.

Development of ADHD: Etiology, Heterogeneity, and Early Life Course

ADHD represents a powerful entry point for developmental approaches to psychopathology due to its major role in early emergence of major life problems. One key issue concerns the role of early environmental risks in etiology and maintenance in the context of genetic liability. Here, psychosocial aspects of development need more attention. A second key issue is that phenotypic heterogeneity requires better resolution if actionable causal mechanisms are to be effectively identified. Here, the interplay of cognition and emotion in the context of a temperament lens is one helpful way forward. A third key issue is the poorly understood yet somewhat striking bifurcation of developmental course in adolescence, when a subgroup seem to have largely benign outcomes, while a larger group continue on a problematic path. A final integrative question concerns the most effective conceptualization of the disorder in relation to broader dysregulation. Key scientific priorities are noted.

ADHD: Current Concepts and Treatments in Children and Adolescents

Attention deficit hyperactivity disorder (ADHD) is among the most frequent disorders within child and adolescent psychiatry, with a prevalence of over 5%. Nosological systems, such as the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5) and the International Classification of Diseases, editions 10 and 11 (ICD-10/11) continue to define ADHD according to behavioral criteria, based on observation and on informant reports. Despite an overwhelming body of research on ADHD over the last 10 to 20 years, valid neurobiological markers or other objective criteria that may lead to unequivocal diagnostic classification are still lacking. On the contrary, the concept of ADHD seems to have become broader and more heterogeneous. Thus, the diagnosis and treatment of ADHD are still challenging for clinicians, necessitating increased reliance on their expertise and experience. The first part of this review presents an overview of the current definitions of the disorder (DSM-5, ICD-10/11). Furthermore, it discusses more controversial aspects of the construct of ADHD, including the dimensional versus categorical approach, alternative ADHD constructs, and aspects pertaining to epidemiology and prevalence. The second part focuses on comorbidities, on the difficulty of distinguishing between "primary" and "secondary" ADHD for purposes of differential diagnosis, and on clinical diagnostic procedures. In the third and most prominent part, an overview of current neurobiological concepts of ADHD is given, including neuropsychological and neurophysiological researches and summaries of current neuroimaging and genetic studies. Finally, treatment options are reviewed, including a discussion of multimodal, pharmacological, and nonpharmacological interventions and their evidence base.

Electroencephalographic and Neuroimaging Asymmetry Correlation in Patients with Attention-Deficit Hyperactivity Disorder

The present study explores the correlation between electroencephalographic and neuroimaging asymmetry index from EEG-MRI functional connectome and EEG power analysis in inattention, motion, and mixed profile subgroups of ADHD. Sixty-two subjects from Healthy Brain Network Biobank of the Child Mind Institute dataset were selected basing on the quotient score. From both MRI and EEG asymmetry index, Pearson's correlation, ANOVA, and partial least square analysis were performed matching left and right brain parcels and channels. The asymmetry index significantly correlated across subjects between fMRI and power-EEG in the inattention group in frontal and temporal areas for theta and alpha bands, an anticorrelation in the same areas for delta band was found. Significant patterns of hemispheric asymmetry index have been reported, involving EEG bands that underlie cognitive impairments in ADHD. Alpha and theta bands were altered in the inattention group of patients, reflecting widespread deficiency of basic attentional processing.

Toward a Revised Nosology for Attention-Deficit/Hyperactivity Disorder Heterogeneity

Attention-deficit/hyperactivity disorder (ADHD) is among the many syndromes in the psychiatric nosology for which etiological signal and clinical prediction are weak. Reducing phenotypic and mechanistic heterogeneity should be useful to arrive at stronger etiological and clinical prediction signals. We discuss key conceptual and methodological issues, highlighting the role of dimensional features aligned with Research Domain Criteria and cognitive, personality, and temperament theory as well as neurobiology. We describe several avenues of work in this area, utilizing different statistical, computational, and machine learning approaches to resolve heterogeneity in ADHD. We offer methodological and conceptual recommendations. Methodologically, we propose that an integrated approach utilizing theory and advanced computational logic to address targeted questions, with consideration of developmental context, can render the heterogeneity problem tractable for ADHD. Conceptually, we conclude that the field is on the cusp of justifying an emotionally dysregulated subprofile in ADHD that may be useful for clinical prediction and treatment testing. Cognitive profiles, while more nascent, may be useful for clinical prediction and treatment assignment in different ways depending on developmental stage. Targeting these psychological profiles for neurobiological and etiological study to capture different pathophysiological routes remains a near-term opportunity. Subtypes are likely to be multifactorial, cut across multiple dimensions, and depend on the research or clinical outcomes of interest for their ultimate selection. In this context parallel profiles based on cognition, emotion, and specific neural signatures appear to be on the horizon, each with somewhat different utilities. Efforts to integrate such cross-cutting profiles within a conceptual dysregulation framework are well underway.

Heterogeneity and Subtyping in Attention-Deficit/Hyperactivity Disorder-Considerations for Emerging Research Using Person-Centered Computational Approaches

Few if any experts believe that existing psychiatric diagnostic categories included in DSM and ICD are actually discrete disease entities. Attention-deficit/hyperactivity disorder (ADHD) is emblematic of the problems in the existing psychiatric classification system. ADHD symptoms reliably cluster into two correlated dimensions in factor analysis. However, children with ADHD vary considerably in their symptom profiles, symptom trajectories, clinical outcomes, and biological and psychological correlates. Thus, the field has sought alternative approaches that harness the dimensions of emotional, cognitive, and behavioral functioning that underlie ADHD and other existing psychiatric categories to create informative phenotypes that improve clinical prediction and clarify etiology. Within ADHD, cognitive (neuropsychological) and temperament/personality features have received considerable attention. In some cases, subphenotypes based on these features appear to improve on existing classifications and could eventually be translated into clinical practice. This review summarizes findings from subphenotyping efforts in ADHD that use cognitive, emotion-related, and other features to highlight major considerations for research applying person-oriented approaches to inform an improved psychiatric nosology. Considerations related to feature selection, validation of newly proposed divisions, defining populations of interest, and incorporating a developmental perspective are discussed.

Emotion-Cognition Interactions in Attention-Deficit/Hyperactivity Disorder: Increased Early Attention Capture and Weakened Attentional Control in Emotional Contexts

BACKGROUND

Emotion dysregulation is a key dimensional trait in psychopathology. It is of particular interest in attention-deficit/hyperactivity disorder (ADHD) because individual differences in emotion dysregulation predict impairment. Despite growing recognition of its importance, an understanding of emotional functioning in ADHD needs to be better integrated with the well-known nonemotional attentional impairments in the disorder. Here, we assess differences in early, reactive and later, regulatory attention to emotional stimuli, as well as how impairments in attentional control to nonemotional stimuli are affected under different emotional contexts.

METHODS

In all, 130 adolescents (nADHD = 61) completed an emotional go/no-go task while 32-channel electroencephalography data were recorded. Reaction time and accuracy were analyzed using the linear ballistic accumulator model.

RESULTS

The multimethod approach provided convergent evidence of increased early, reactive attention capture and overarousal (faster drift rates, increased P1) by positively valenced stimuli in ADHD, but no differences in later attention to emotional stimuli. Overarousal in positive-valence contexts appeared to exacerbate existing ADHD-related impairments in attentional control to nonemotional stimuli as well (reduced N2 amplitude). In contrast, positive-valence contexts facilitated attentional control to nonemotional stimuli for typically developing adolescents.

CONCLUSIONS

Results highlight the dynamic interaction of emotion with attentional control in ADHD. Distinguishing reactive and regulatory contributions to emotion dysregulation has been informative for clarifying mechanisms and spurring the development of novel interventions in other disorders. It can be informative in ADHD as well.

ADHD and ODD Symptoms in Toddlers: Common and Specific Associations with Temperament Dimensions

The aim of this work was to study the relationship between temperament and signs of psychopathology in typically developing toddlers. More specifically, Attentional Deficit Hyperactivity Disorder (ADHD) and Oppositional Defiant Disorder (ODD) symptoms were analyzed in connection with fine-grained temperament dimensions. The sample was composed of 65 toddlers aged between 18 and 35 months. Bivariate correlations showed that higher levels of negative emotionality and approach tendencies, and lower levels of inhibitory control, were related to more ADHD and ODD manifestations. Bivariate correlations also indicated unique associations: lower levels of soothability were associated with higher ODD symptoms, whereas lower attentional focusing and low-intensity pleasure were related with higher ADHD symptoms. Additionally, regression and path analysis models indicated that ADHD was predominantly associated with attentional focusing and motor activation whereas ODD was most closely related to frustration. Our findings highlight the relevance of studying early correlates of psychopathological manifestations to identify children who could benefit from prevention and early intervention programs.

Development of a Composite Primary Outcome Score for Children with Attention-Deficit/Hyperactivity Disorder and Emotional Dysregulation

Objective: Study goals were to (1) provide a rationale for developing a composite primary outcome score that includes symptom severity for attention-deficit/hyperactivity disorder (ADHD) and emotional dysregulation, plus symptom-induced impairment; (2) demonstrate weighting methods to calculate the composite score using a sample of children diagnosed with ADHD and aggression; and (3) identify the optimal weighting method most sensitive to change, as measured by effect sizes. Methods: We conducted secondary data analyses from the previously conducted Treatment of Severe Childhood Aggression (TOSCA) study. Children aged 6-12 years were recruited through academic medical centers or community referrals. The composite primary outcome comprised the ADHD, oppositional defiant disorder, disruptive mood dysregulation disorder, and peer conflict subscales from the Child and Adolescent Symptom Inventory (CASI), a DSM (Diagnostic and Statistical Manual)-referenced rating scale of symptom severity and symptom-induced impairment. Five weighting methods were tested based on input from senior statisticians. Results: The composite score demonstrated a larger (Cohen's d) effect size than the individual CASI subscales, irrespective of the weighting method (10%-55% larger). Across all weighting methods, effect sizes were similar and substantial: approximately a two-standard deviation symptom reduction (range: -1.97 to -2.04), highest for equal item and equal subscale weighting, was demonstrated, from baseline to week 9, among all TOSCA participants. The composite score showed a medium positive correlation with the Clinical Global Impressions-Severity scores, 0.46-0.47 for all weighting methods. Conclusions: A composite score that included severity and impairment ratings of ADHD and emotional dysregulation demonstrated a more robust pre-post change than individual subscales. This composite may be a more useful indicator of clinically relevant improvement in heterogeneous samples with ADHD than single subscales, avoiding some of the statistical limitations associated with multiple comparisons. Among the five similar weighting methods, the two best appear to be the equal item and equal subscale weighting methods.

The Validity of a Frustration Paradigm to Assess the Effect of Frustration on Cognitive Control in School-Age Children

Irritability refers to a proneness for anger, and is a symptom of internalizing and externalizing psychopathology. Since irritability is associated with significant cross-sectional and longitudinal impairments, research on the behavioral and neural correlates of pediatric irritability in populations at risk for significant irritability is of paramount importance. Irritability can be assessed in the laboratory using behavioral paradigms that elicit frustration. Few behavioral frustration paradigms have been designed to measure the effects of frustration on cognitive control. Therefore, the goal of the present study was to validate a behavioral frustration paradigm for use in school-age children which addressed some of the limitations of prior research. Participants included children, ages 8-12 years, who were either typically developing (TD; n = 38) or diagnosed with attention-deficit/hyperactivity disorder (ADHD; n = 67), which provided a sample of children with a range of baseline irritability. All participants completed the Frustration Go/No-Go (GNG) task, and self-reported irritability was assessed using the Affective Reactivity Index. Results showed that across participants, self-reported frustration, commission error rate, and tau all increased with the addition of frustration, with similar effect sizes in ADHD and TD groups. Further, self-reported irritability, moreso than ADHD symptoms, predicted changes in self-reported frustration during the task. Together, these results support the construct validity of the Frustration GNG task as a means of assessing the effect of frustration on cognitive control. Clinical applications and future directions are discussed.

The Clinician Affective Reactivity Index: Validity and Reliability of a Clinician-Rated Assessment of Irritability

Irritability is impairing in youth and is the core feature of disruptive mood dysregulation disorder (DMDD). Currently, there are no established clinician-rated instruments to assess irritability in pediatric research and clinical settings. Clinician-rated measures ensure consistency of assessment across patients and are important specifically for treatment research. Here, we present data on the psychometric properties of the Clinician Affective Reactivity Index (CL-ARI), the first semistructured interview focused on pediatric irritability. The CL-ARI was administered to a transdiagnostic sample of 98 youth (M age = 12.66, SD = 2.47; 41% female). With respect to convergent validity, CL-ARI scores were (a) significantly higher for youth with DMDD than for any other diagnostic group, and (b) showed uniquely strong associations with other clinician-, parent-, and youth-report measures of irritability compared to measures of related constructs, such as anxiety. The three subscales of the CL-ARI (temper outbursts, irritable mood, impairment) showed excellent internal consistency. Test-retest reliability of the CL-ARI was adequate. These data support that irritability can be feasibly, validly, and reliably assessed by clinicians using the CL-ARI. A validated, gold-standard assessment of pediatric irritability is critical in advancing research and treatment efforts.

Evaluating chronic emotional dysregulation and irritability in relation to ADHD and depression genetic risk in children with ADHD

BACKGROUND

A central nosological problem concerns the etiological relationship of emotional dysregulation with ADHD. Molecular genetic risk scores provide a novel method for informing this question.

METHODS

Participants were 514 community-recruited children of Northern European descent age 7-11 defined as ADHD or non-ADHD by detailed research evaluation. Parents-rated ADHD on standardized ratings and child temperament on the Temperament in Middle Childhood Questionnaire (TMCQ) and reported on ADHD and comorbid disorders by semi-structured clinical interview. Categorical and dimensional variables were created for ADHD, emotional dysregulation (implicating disruption of regulation of both anger-irritability and of positive valence surgency-sensation seeking), and irritability alone (anger dysregulation). Genome-wide polygenic risk scores (PRS) were computed for ADHD and depression genetic liability. Structural equation models and computationally derived emotion profiles guided analysis.

RESULTS

The ADHD PRS was associated in variable-centered analyses with irritability (β = .179, 95% CI = 0.087-0.280; ΔR²  = .034, p < .0002), but also with surgency/sensation seeking (B = .146, 95%CI = 0.052-0.240, ΔR² =.022, p = .002). In person-centered analysis, the ADHD PRS was elevated in the emotion dysregulation ADHD group versus other ADHD children (OR = 1.44, 95% CI = 1.03-2.20, Nagelkerke ΔR²  = .013, p = .033) but did not differentiate irritable from surgent ADHD profiles. All effects were independent of variation in ADHD severity across traits or groups. The depression PRS was related to oppositional defiant disorder but not to ADHD emotion dysregulation.

CONCLUSIONS

Irritability-anger and surgency-sensation seeking, as forms of negative and positively valenced dysregulated affect in ADHD populations, both relate principally to ADHD genetic risk and not mood-related genetic risk.

Rationale and design of an international randomized placebo-controlled trial of a 36-ingredient micronutrient supplement for children with ADHD and irritable mood: The Micronutrients for ADHD in Youth (MADDY) study

Background

Attention-Deficit/Hyperactivity Disorder (ADHD) is a chronic neurodevelopmental disorder affecting up to 9% of children and substantial numbers of adults. Existing pharmacologic treatments often improve symptoms, but concerns exist over side effects, stigma, potential long-term health effects, and residual irritability, often treated with adjunctive antipsychotics. To address public and clinician demand for non-pharmacologic evidence-based treatments, this study will examine efficacy of a 36-ingredient micronutrient (vitamin/mineral) supplement as treatment for children with ADHD and irritability.

Methods

An international team of experts in ADHD, mood dysregulation, nutrition, epidemiology, and clinical trials conferred to develop/refine a protocol powered to detect a medium effect. The study will employ a fully-blind randomized controlled trial (RCT) design, comparing the micronutrient supplement to matched placebo in 135 children aged 6-12 with ADHD symptoms and irritability, based on the parent-rated Child and Adolescent Symptom Inventory-5 (CASI-5). Irritability will be measured by at least one symptom of oppositional defiant disorder (ODD) or disruptive mood dysregulation disorder (DMDD). Based on research suggesting an irritable ADHD subtype, the primary outcome will be a composite score comprised of the CASI-5 subscales: ADHD, ODD, DMDD, and the Peer Conflict Scale, which assesses anger and aggression perpetrated towards peers. Participants will provide biological samples (blood, urine, saliva, hair and stool) to explore the micronutrients' mechanisms of action.

Discussion

This study is the first adequately powered RCT in North America to examine both behavioral responses to, and biological mechanisms of, micronutrients for ADHD and irritability in children. If found efficacious, broad-spectrum micronutrients, given at therapeutic doses, may provide an evidence-based alternative to prescription medications for ADHD and associated irritability.

Trial registration

NCT03252522. Registered 26 July 2017.

The relationship between alpha asymmetry and ADHD depends on negative affect level and parenting practices

Atypical frontal alpha asymmetry is associated with the approach/withdrawal and affective processes implicated in many psychiatric disorders. Rightward alpha asymmetry, associated with high approach, is a putative endophenotype for attention deficit/hyperactivity disorder (ADHD). However, findings are inconsistent, likely because of a failure to consider emotional heterogeneity within the ADHD population. In addition, how this putative risk marker interacts with environmental factors known to increase symptom severity, such as parenting practices, has not been examined. The current study examined patterns of alpha asymmetry in a large sample of adolescents with and without ADHD, including the moderating role of negative affect and inconsistent discipline. Resting-state EEG was recorded from 169 well-characterized adolescents (nADHD = 79). Semi-structured clinical interviews and well-validated rating scales were used to create composites for negative affect and inconsistent discipline. The relationship between alpha asymmetry and ADHD diagnosis was moderated by negative affect. Right asymmetry was present only for those with ADHD and low levels of negative affect. In addition, greater right alpha asymmetry predicted severity of ADHD symptoms for those with the disorder, but only in the context of inconsistent parenting practices. Results confirm right alpha asymmetry is a possible endophenotype in ADHD but highlight the need to consider emotional heterogeneity and how biological risk interacts with child environment in order to fully characterize its relationship to disorder liability and severity.