The dimensional nature of externalizing behaviors in adolescence: evidence from a direct comparison of categorical, dimensional, and hybrid models

Prevalence of externalising disorder comorbidities in adolescents: a systematic review and meta-analysis protocol

INTRODUCTION

Externalising disorders are some of the most prevalent problems in childhood and particularly during adolescence that can change into more severe psychopathology in adulthood if left unattended. In the research literature, these disorders include attention deficit/hyperactivity disorder, oppositional/defiant disorder, conduct disorder and substance use disorders. The comorbidity prevalence of these disorders is significant and cannot be considered a random factor. The dimensional structure of psychopathology has always been studied by researchers to address disorder comorbidities and aetiology. There has always been controversy over the number of spectra and the lower levels. Currently, the new top-down, Hierarchical Taxonomy of Psychopathology model conceptualising psychopathology is being used, which is a dimensional classification system for the different spectra of psychopathology based on a combination of conceptual modelling and factor analysis of symptoms. This systematic review investigates the comorbidity prevalence of spectra of externalising disorders to provide valuable information and feedback on this model.

METHODS AND ANALYSIS

This systematic review will include all the studies conducted from 1/1/1990 to 1/12/2020 to examine the prevalence and comorbidity of each of the externalising disorders in the general population, schools and outpatients using any instrument (questionnaires or interviews). There will be no language restrictions in selecting the studies. The studies are age restricted and must be conducted on adolescents only, but there are no restrictions on the gender and nationality of the participants.

ETHICS AND DISSEMINATION

This systematic review is based on previously published articles and therefore will not require ethical approval. The results of the systematic review will be disseminated as publication in a peer-reviewed journal and conference presentation.

PROSPERO REGISTRATION NUMBER

CRD42022327629.

Conduct problems are associated with accelerated thinning of emotion-related cortical regions in a community-based sample of adolescents

Few studies have examined the association between conduct problems and cerebral cortical development. Herein, we characterize the association between age-related brain change and conduct problems in a large longitudinal, community-based sample of adolescents. 1,039 participants from the IMAGEN study possessed psychopathology and surface-based morphometric data at study baseline (M = 14.42 years, SD = 0.40; 559 females) and 5-year follow-up. Self-reports of conduct problems were obtained using the Strengths and Difficulties Questionnaire (SDQ). Vertex-level linear mixed effects models were implemented using the Matlab toolbox, SurfStat. To investigate the extent to which cortical thickness maturation was qualified by dimensional measures of conduct problems, we tested for an interaction between age and SDQ Conduct Problems (CP) score. There was no main effect of CP score on cortical thickness; however, a significant "Age by CP" interaction was revealed in bilateral insulae, left inferior frontal gyrus, left rostral anterior cingulate, left posterior cingulate, and bilateral inferior parietal cortices. Across regions, follow-up analysis revealed higher levels of CP were associated with accelerated age-related thinning. Findings were not meaningfully altered when controlling for alcohol use, co-occurring psychopathology, and socioeconomic status. Results may help to further elucidate neurodevelopmental patterns linking adolescent conduct problems with adverse adult outcomes.

The Genetic, Environmental, and Cultural Forces Influencing Youth Antisocial Behavior Are Tightly Intertwined

The aggressive and rule-breaking behaviors that constitute youth antisocial behavior (ASB) are shaped by intertwined genetic, developmental, familial, spatial, temporal, cultural, interpersonal, and contextual influences operating across multiple levels of analysis. Genetic influences on ASB, for example, manifest in different ways during different developmental periods, and do so in part as a function of exposure to harsh parenting, delinquent peers, and disadvantaged neighborhoods. There is also clear evidence documenting societal effects, time-period effects, sex-assigned-at-birth effects, and cohort effects, all of which point to prominent (and possibly interconnected) cultural influences on ASB. In short, ASB is shaped by individuals' current and prior environmental experiences, genetic risks, and the time and place in which they live. This review seeks to illuminate already documented instances of interplay among the multilevel etiologic forces impinging on youth ASB, with the goal of facilitating additional research.

Validity and utility of Hierarchical Taxonomy of Psychopathology (HiTOP): III. Emotional dysfunction superspectrum

The Hierarchical Taxonomy of Psychopathology (HiTOP) is a quantitative nosological system that addresses shortcomings of traditional mental disorder diagnoses, including arbitrary boundaries between psychopathology and normality, frequent disorder co-occurrence, substantial heterogeneity within disorders, and diagnostic unreliability over time and across clinicians. This paper reviews evidence on the validity and utility of the internalizing and somatoform spectra of HiTOP, which together provide support for an emotional dysfunction superspectrum. These spectra are composed of homogeneous symptom and maladaptive trait dimensions currently subsumed within multiple diagnostic classes, including depressive, anxiety, trauma-related, eating, bipolar, and somatic symptom disorders, as well as sexual dysfunction and aspects of personality disorders. Dimensions falling within the emotional dysfunction superspectrum are broadly linked to individual differences in negative affect/neuroticism. Extensive evidence establishes that dimensions falling within the superspectrum share genetic diatheses, environmental risk factors, cognitive and affective difficulties, neural substrates and biomarkers, childhood temperamental antecedents, and treatment response. The structure of these validators mirrors the quantitative structure of the superspectrum, with some correlates more specific to internalizing or somatoform conditions, and others common to both, thereby underlining the hierarchical structure of the domain. Compared to traditional diagnoses, the internalizing and somatoform spectra demonstrated substantially improved utility: greater reliability, larger explanatory and predictive power, and greater clinical applicability. Validated measures are currently available to implement the HiTOP system in practice, which can make diagnostic classification more useful, both in research and in the clinic.

Genetic association study of childhood aggression across raters, instruments, and age

Childhood aggressive behavior (AGG) has a substantial heritability of around 50%. Here we present a genome-wide association meta-analysis (GWAMA) of childhood AGG, in which all phenotype measures across childhood ages from multiple assessors were included. We analyzed phenotype assessments for a total of 328 935 observations from 87 485 children aged between 1.5 and 18 years, while accounting for sample overlap. We also meta-analyzed within subsets of the data, i.e., within rater, instrument and age. SNP-heritability for the overall meta-analysis (AGGoverall) was 3.31% (SE = 0.0038). We found no genome-wide significant SNPs for AGGoverall. The gene-based analysis returned three significant genes: ST3GAL3 (P = 1.6E-06), PCDH7 (P = 2.0E-06), and IPO13 (P = 2.5E-06). All three genes have previously been associated with educational traits. Polygenic scores based on our GWAMA significantly predicted aggression in a holdout sample of children (variance explained = 0.44%) and in retrospectively assessed childhood aggression (variance explained = 0.20%). Genetic correlations (rg) among rater-specific assessment of AGG ranged from rg = 0.46 between self- and teacher-assessment to rg = 0.81 between mother- and teacher-assessment. We obtained moderate-to-strong rgs with selected phenotypes from multiple domains, but hardly with any of the classical biomarkers thought to be associated with AGG. Significant genetic correlations were observed with most psychiatric and psychological traits (range [Formula: see text]: 0.19-1.00), except for obsessive-compulsive disorder. Aggression had a negative genetic correlation (rg = ~-0.5) with cognitive traits and age at first birth. Aggression was strongly genetically correlated with smoking phenotypes (range [Formula: see text]: 0.46-0.60). The genetic correlations between aggression and psychiatric disorders were weaker for teacher-reported AGG than for mother- and self-reported AGG. The current GWAMA of childhood aggression provides a powerful tool to interrogate the rater-specific genetic etiology of AGG.

Structural Brain Development and Aggression: A Longitudinal Study in Late Childhood

This longitudinal study examined the neurodevelopmental correlates of aggression in children, focusing on structural brain properties. A community sample of 110 (60 females) children participated at age 8 years and again at age 10 years. Brain structure was assessed by using magnetic resonance imaging (MRI), and parents reported on child aggression using the Child Behavior Checklist. Analyses examined the relationship between aggression and development of volume of subcortical regions, cortical thickness, and subcortical-cortical structural coupling. Females with relatively high aggression exhibited reduced right hippocampal growth over time. Across males and females, aggression was associated with amygdala- and hippocampal-cortical developmental coupling, with findings for amygdala-cortical coupling potentially indicating reduced top-down prefrontal control of the amygdala in those with increasing aggression over time. Findings suggest that aggressive behaviors may be associated with alterations in normative brain development; however, results were not corrected for multiple comparisons and should be interpreted with caution.

COVID Stress Syndrome: Clinical and Nosological Considerations

PURPOSE OF REVIEW

To review the current state of knowledge on the newly proposed COVID Stress Syndrome.

RECENT FINDINGS

The syndrome consists of five inter-correlated elements: (a) fear of SARSCoV2 infection and fear of coming into contact with objects or surfaces contaminated with the coronavirus; (b) fear of socio-economic impacts of the pandemic; (c) fear of foreigners for fear that they are infected; (d) pandemic-related compulsive checking and reassurance-seeking; and (e) pandemic-related traumatic stress symptoms. A severe form of the syndrome, characterized by clinically significant distress and impairment in functioning, is the COVID Stress Disorder, which is regarded as a pandemic-related adjustment disorder. Several treatment options exist but further research is needed. Research during the COVID-19 pandemic has identified a pandemic-related adjustment disorder. The diagnosis of COVID Stress Syndrome should be made only after ruling out other disorders that could potentially account for the pattern of symptoms, such as obsessive-compulsive disorder and posttraumatic stress disorder. Further studies are needed to investigate the long-term course of the syndrome. Similar adjustment disorders may arise in future pandemics. Accordingly, understanding the COVID Stress Syndrome may facilitate efforts to understand and treat psychopathology in future pandemics.

Les progrès dans la réalisation de la classification quantitative de la psychopathologie☆

Shortcomings of approaches to classifying psychopathology based on expert consensus have given rise to contemporary efforts to classify psychopathology quantitatively. In this paper, we review progress in achieving a quantitative and empirical classification of psychopathology. A substantial empirical literature indicates that psychopathology is generally more dimensional than categorical. When the discreteness versus continuity of psychopathology is treated as a research question, as opposed to being decided as a matter of tradition, the evidence clearly supports the hypothesis of continuity. In addition, a related body of literature shows how psychopathology dimensions can be arranged in a hierarchy, ranging from very broad "spectrum level" dimensions, to specific and narrow clusters of symptoms. In this way, a quantitative approach solves the "problem of comorbidity" by explicitly modeling patterns of co-occurrence among signs and symptoms within a detailed and variegated hierarchy of dimensional concepts with direct clinical utility. Indeed, extensive evidence pertaining to the dimensional and hierarchical structure of psychopathology has led to the formation of the Hierarchical Taxonomy of Psychopathology (HiTOP) Consortium. This is a group of 70 investigators working together to study empirical classification of psychopathology. In this paper, we describe the aims and current foci of the HiTOP Consortium. These aims pertain to continued research on the empirical organization of psychopathology; the connection between personality and psychopathology; the utility of empirically based psychopathology constructs in both research and the clinic; and the development of novel and comprehensive models and corresponding assessment instruments for psychopathology constructs derived from an empirical approach.

Examining cognitive control and reward interactions in adolescent externalizing symptoms

During adolescence, rapid development and reorganization of the dopaminergic system supports increasingly sophisticated reward learning and the ability to exert behavioral control. Disruptions in the ability to exert control over previously rewarded behavior may underlie some forms of adolescent psychopathology. Specifically, symptoms of externalizing psychopathology may be associated with difficulties in flexibly adapting behavior in the context of reward. However, the direct interaction of cognitive control and reward learning in adolescent psychopathology symptoms has not yet been investigated. The present study used a Research Domain Criteria framework to investigate whether behavioral and neuronal indices of inhibition to previously rewarded stimuli underlie individual differences in externalizing symptoms in N = 61 typically developing adolescents. Using a task that integrates the Monetary Incentive Delay and Go-No-Go paradigms, we observed a positive association between externalizing symptoms and activation of the left middle frontal gyrus during response inhibition to cues with a history of reward. These associations were robust to controls for internalizing symptoms and neural recruitment during inhibition of cues with no reward history. Our findings suggest that inhibitory control over stimuli with a history of reward may be a useful marker for future inquiry into the development of externalizing psychopathology in adolescence.

The distinction between symptoms and traits in the Hierarchical Taxonomy of Psychopathology (HiTOP)

The Hierarchical Taxonomy of Psychopathology (HiTOP) is an empirically and quantitatively derived dimensional classification system designed to describe the features of psychopathology and, ultimately, to replace categorical nosologies. Among the constructs that HiTOP organizes are "symptom components" and "maladaptive traits," but past HiTOP publications have not fully explicated the distinction between symptoms and traits. We propose working definitions of symptoms and traits and explore challenges, exceptions, and remaining questions. Specifically, we propose that the only systematic difference between symptoms and traits in HiTOP is one of time frame. Maladaptive traits are dispositional constructs that describe persistent tendencies to manifest features of psychopathology, whereas symptoms are features of psychopathology as they are manifest during any specific time period (from moments to days to months). This has the consequence that almost every HiTOP dimension, at any level of the hierarchy, can be assessed as either a trait or a symptom dimension, by adjusting the framing of the assessment. We discuss the implications of these definitions for causal models of the relations between symptoms and traits and for distinctions between psychopathology, normal personality variation, and dysfunction.

Integrating the Hierarchical Taxonomy of Psychopathology (HiTOP) into clinical practice

OBJECTIVE

Diagnosis is a cornerstone of clinical practice for mental health care providers, yet traditional diagnostic systems have well-known shortcomings, including inadequate reliability, high comorbidity, and marked within-diagnosis heterogeneity. The Hierarchical Taxonomy of Psychopathology (HiTOP) is a data-driven, hierarchically based alternative to traditional classifications that conceptualizes psychopathology as a set of dimensions organized into increasingly broad, transdiagnostic spectra. Prior work has shown that using a dimensional approach improves reliability and validity, but translating a model like HiTOP into a workable system that is useful for health care providers remains a major challenge.

METHOD

The present work outlines the HiTOP model and describes the core principles to guide its integration into clinical practice.

RESULTS

Potential advantages and limitations of the HiTOP model for clinical utility are reviewed, including with respect to case conceptualization and treatment planning. A HiTOP approach to practice is illustrated and contrasted with an approach based on traditional nosology. Common barriers to using HiTOP in real-world health care settings and solutions to these barriers are discussed.

CONCLUSIONS

HiTOP represents a viable alternative to classifying mental illness that can be integrated into practice today, although research is needed to further establish its utility. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Can the Social Behavior Questionnaire Help Meet the Need for Dimensional, Transdiagnostic Measures of Childhood and Adolescent Psychopathology?

Abstract. The shift toward transdiagnostic and dimensional approaches to psychopathology research has created a growing need for psychometric assessments that reflect this conceptualization. We aimed to test whether an omnibus measure of psychopathology, the Social Behavior Questionnaire (SBQ), has suitable properties to serve as a dimensional, transdiagnostic assessment. We used an item response theory (IRT) approach to evaluate the reliable ranges of measurement of the psychopathology dimensions measured by the SBQ. For the dimensions of attention-deficit hyperactivity disorder (ADHD), Prosociality, Internalizing, and Externalizing, the SBQ can provide a reliable measure for below average to very high levels in a normative sample.

Comparative responsiveness of generic versus disorder-specific instruments for depression: An assessment in three longitudinal datasets

BACKGROUND

Routine outcome monitoring (ROM) may enhance individual treatment and is also advocated as a means to compare the outcome of different treatment programs or providers. There is debate on the optimal instruments to be used for these separate tasks.

METHODS

Three sets with longitudinal data from ROM were analyzed with correlational analysis and repeated measures ANOVAs, allowing for a head-to-head comparison of measures regarding their sensitivity to detect change. The responsiveness of three disorder-specific instruments, the Beck Depression Inventory, the Inventory of Depressive Symptoms, and the Mood and Anxiety Symptoms Questionnaire, was compared to three generic instruments, the Symptom Checklist (SCL-90), the Outcome Questionnaire (OQ-45), and the Brief Symptom Inventory, respectively.

RESULTS

In two of the three datasets, disorder-specific measures were more responsive compared to the total score on generic instruments. Subscale scores for depression embedded within generic instruments are second best and almost match disorder-specific scales in responsiveness. No evidence of a desynchronous response on outcome measures was found.

LIMITATIONS

The present study compares measures head-to-had, and responsiveness is not assessed against an external criterion, such as clinical recovery.

DISCUSSION

Disorder-specific measures yield the most precise assessment for individual treatment and are recommended for clinical use. Generic measures may allow for comparisons across diagnostic groups and their embedded subscales approach the responsiveness of disorder-specific measures.

Progress in achieving quantitative classification of psychopathology

Shortcomings of approaches to classifying psychopathology based on expert consensus have given rise to contemporary efforts to classify psychopathology quantitatively. In this paper, we review progress in achieving a quantitative and empirical classification of psychopathology. A substantial empirical literature indicates that psychopathology is generally more dimensional than categorical. When the discreteness versus continuity of psychopathology is treated as a research question, as opposed to being decided as a matter of tradition, the evidence clearly supports the hypothesis of continuity. In addition, a related body of literature shows how psychopathology dimensions can be arranged in a hierarchy, ranging from very broad "spectrum level" dimensions, to specific and narrow clusters of symptoms. In this way, a quantitative approach solves the "problem of comorbidity" by explicitly modeling patterns of co-occurrence among signs and symptoms within a detailed and variegated hierarchy of dimensional concepts with direct clinical utility. Indeed, extensive evidence pertaining to the dimensional and hierarchical structure of psychopathology has led to the formation of the Hierarchical Taxonomy of Psychopathology (HiTOP) Consortium. This is a group of 70 investigators working together to study empirical classification of psychopathology. In this paper, we describe the aims and current foci of the HiTOP Consortium. These aims pertain to continued research on the empirical organization of psychopathology; the connection between personality and psychopathology; the utility of empirically based psychopathology constructs in both research and the clinic; and the development of novel and comprehensive models and corresponding assessment instruments for psychopathology constructs derived from an empirical approach.

Measurement framework for the Environmental influences on Child Health Outcomes research program

PURPOSE OF REVIEW

Diverse methodological approaches pose significant challenges to assess environmental exposure effects on child health outcomes. Although transdisciplinary research efforts offer unique opportunities for understanding the complex and multidimensional facets of lifespan health and disease trajectories, a shared measurement strategy is necessary for ensuring cohesion and comprehensibility across disciplines and domains.

RECENT FINDINGS

Exposure science often focuses on one life stage, one primary outcome domain and/or one environmental context without regard for understanding the complexity of exposome pathways and outcomes across a developmental continuum. As part of the National Institutes of Health Environmental influences on Child Health Outcomes Program, the Person Reported Outcomes Core developed a unifying measurement framework that takes a lifespan development approach to assess physical, mental and social health outcomes within the complex matrix of environmental exposure pathways.

SUMMARY

The proposed framework offers a shared methodological approach to health outcome assessment, with a particular emphasis on person-reported outcomes. This framework will be instrumental for future large-scale consortia and transdisciplinary team science efforts by providing a common structure, measurement guidance and consistent terminology.

Validating dimensions of psychosis symptomatology: Neural correlates and 20-year outcomes

Heterogeneity of psychosis presents significant challenges for classification. Between 2 and 12 symptom dimensions have been proposed, and consensus is lacking. The present study sought to identify uniquely informative models by comparing the validity of these alternatives. An epidemiologic cohort of 628 first-admission inpatients with psychosis was interviewed 6 times over 2 decades and completed an electrophysiological assessment of error processing at year 20. We first analyzed a comprehensive set of 49 symptoms rated by interviewers at baseline, progressively extracting from 1 to 12 factors. Next, we compared the ability of resulting factor solutions to (a) account for concurrent neural dysfunction and (b) predict 20-year role, social, residential, and global functioning, and life satisfaction. A four-factor model showed incremental validity with all outcomes, and more complex models did not improve explanatory power. The 4 dimensions-reality distortion, disorganization, inexpressivity, and apathy/asociality-were replicable in 5 follow-ups, internally consistent, stable across assessments, and showed strong discriminant validity. These results reaffirm the value of separating disorganization and reality distortion, are consistent with recent findings distinguishing inexpressivity and apathy/asociality, and suggest that these 4 dimensions are fundamental to understanding neural abnormalities and long-term outcomes in psychosis. (PsycINFO Database Record

Mental disorder comorbidity and treatment utilization

OBJECTIVE

Effective interventions have been developed for myriad common psychological and substance use disorders, though they remain highly underutilized. Previous research has shown that the likelihood of treatment utilization varies across disorder diagnosis. However, studies that focus on individual disorders have resulted in a large, piecemeal literature that neglects the high rates of multivariate comorbidity. The current study investigated the association between treatment utilization and transdiagnostic comorbidity factors.

METHODS

In a nationally representative sample of the United States adult population (N=34,653), we applied the internalizing-externalizing latent comorbidity model to examine its association with lifetime utilization of various treatments for mood, anxiety, and substance use disorders.

RESULTS

Both internalizing and externalizing transdiagnostic factors were positively associated with all forms of treatment utilization. Stronger within-domain domain (e.g., internalizing's association with mood or anxiety treatment) than between-domain (e.g., internalizing's association with substance use disorder treatment) associations were found. Significant antagonistic internalizing-by-externalizing interactions were also observed.

CONCLUSIONS

These results underscore the importance of applying a nuanced approach to modeling comorbidity when predicting treatment utilization. Clinical implications are discussed.

What do clinicians treat: Diagnoses or symptoms? The incremental validity of a symptom-based, dimensional characterization of emotional disorders in predicting medication prescription patterns

BACKGROUND

Although practice guidelines are based on disorders specified in diagnostic manuals, such as the DSM, practitioners appear to follow symptoms when making treatment decisions. Psychiatric medication is generally prescribed in a transdiagnostic manner, further highlighting how symptoms, not diagnoses, often guide clinical practice. A quantitative approach to nosology promises to provide better guidance as it describes psychopathology dimensionally and its organization reflects patterns of covariation among symptoms.

AIM

To investigate whether a quantitative classification of emotional disorders can account for naturalistic medication prescription patterns better than traditional diagnoses.

METHODS

Symptom dimensions and DSM diagnoses of emotional disorders, as well as prescribed medications, were assessed using interviews in a psychiatric outpatient sample (N=318, mean age 42.5years old, 59% female, 81% Caucasian).

RESULTS

Each diagnosis was associated with prescription of multiple medication classes, and most medications were associated with multiple disorders. This was largely due to heterogeneity of clinical diagnoses, with narrow, homogenous dimensions underpinning diagnoses showing different medication profiles. Symptom dimensions predicted medication prescription better than DSM diagnoses, irrespective of whether this was examined broadly across all conditions, or focused on a specific disorder and medication indicated for it.

CONCLUSIONS

Psychiatric medication was prescribed in line with symptoms rather than DSM diagnoses. A quantitative approach to nosology may better reflect treatment planning and be a more effective guide to pharmacotherapy than traditional diagnoses. This adds to a diverse body of evidence about superiority of the quantitative system in practical applications and highlights its potential to improve psychiatric care.

The Phenomenology of Non-Aggressive Antisocial Behavior During Childhood

Although the phenomenology of overt or aggressive antisocial behavior during childhood is well-documented, far less is known about covert or non-aggressive, rule-breaking (RB) antisocial behavior. Gaps in knowledge include issues as basic as RB's typical symptom presentation during childhood and which symptoms differ across sex. The current study sought to fill these gaps in the literature by establishing the prevalence and psychometric properties of specific RB behaviors in a sample of 1022 twin boys and 1010 twin girls between the ages of 6 and 10 years. Legal RB behaviors (e.g., breaking rules, swears, lying or cheating) were present to varying degrees in most children, regardless of whether or not they passed the clinical threshold for RB. They were also more common in boys than in girls regardless of their clinical status. In sharp contrast, illegal RB behaviors (e.g., stealing, vandalism, setting fires) were rarely observed in typically-developing children, but were seen at moderate levels in boys and girls with clinically-significant levels of RB. Moreover, sex differences in illegal RB behaviors were observed only for those youth with clinically meaningful levels of RB. Such findings collectively imply that while legal RB behaviors can be found (albeit at different frequencies) in children with and without clinically meaningful levels of RB, illegal RB behaviors may function as relatively 'unambiguous' indicator of clinically-significant levels of RB.

Avoidance in hypochondriasis

The DSM-5 diagnosis of illness anxiety disorder adds avoidance as a component of a behavioral response to illness fears - one that was not present in prior DSM criteria of hypochondriasis. However, maladaptive avoidance as a necessary or useful criterion has yet to be empirically supported.

METHODS

195 individuals meeting DSM-IV criteria for hypochondriasis based on structured interview completed a variety of self-report and clinician-administered assessments. Data on maladaptive avoidance were obtained using the six-item subscale of the clinician-administered Hypochondriasis - Yale Brown Obsessive Compulsive Scale - Modified. To determine if avoidance emerged as a useful indicator in hypochondriasis, we compared the relative fit of continuous latent trait, categorical latent class, and hybrid factor mixture models.

RESULTS

A two-class factor mixture model fit the data best, with Class 1 (n=147) exhibiting a greater level of severity of avoidance than Class 2 (n=48). The more severely avoidant group was found to have higher levels of hypochondriacal symptom severity, functional impairment, and anxiety, as well as lower quality of life.

CONCLUSION

These results suggest that avoidance may be a valid behavioral construct and a useful component of the new diagnostic criteria of illness anxiety in the DSM-5, with implications for somatic symptom disorder.

The relation between attachment, personality, internalizing, and externalizing dimensions in adolescents with borderline personality disorder

The relation between attachment and personality features is an important field to explore in adolescent borderline personality disorder (BPD), and previous research has shown that personality features may be conceptualized within latent internalizing and externalizing dimensions. This cross-sectional study used a structural equation model to examine the association between the BPD participants' perception of attachment and personality features, mediated by the underlying internalizing/externalizing personality dimensions. Data were analyzed for 60 adolescents, ages 15 to 18 years, diagnosed with BPD who completed attachment and personality self-report measures. The authors' results showed a good fit of the model, suggesting a significant association between attachment and the internalizing/externalizing dimensions, which simultaneously congregate and influence personality traits. The perception of attachment anxiety was positively related to the internalizing dimension and at the same time negatively related to the externalizing dimension. However, the perception of attachment avoidance was not related to internalizing or externalizing personality dimensions.

The neurobiological basis of human aggression: A review on genetic and epigenetic mechanisms

Aggression is an evolutionary conserved behavior present in most species including humans. Inadequate aggression can lead to long-term detrimental personal and societal effects. Here, we differentiate between proactive and reactive forms of aggression and review the genetic determinants of it. Heritability estimates of aggression in general vary between studies due to differing assessment instruments for aggressive behavior (AB) as well as age and gender of study participants. In addition, especially non-shared environmental factors shape AB. Current hypotheses suggest that environmental effects such as early life stress or chronic psychosocial risk factors (e.g., maltreatment) and variation in genes related to neuroendocrine, dopaminergic as well as serotonergic systems increase the risk to develop AB. In this review, we summarize the current knowledge of the genetics of human aggression based on twin studies, genetic association studies, animal models, and epigenetic analyses with the aim to differentiate between mechanisms associated with proactive or reactive aggression. We hypothesize that from a genetic perspective, the aminergic systems are likely to regulate both reactive and proactive aggression, whereas the endocrine pathways seem to be more involved in regulation of reactive aggression through modulation of impulsivity. Epigenetic studies on aggression have associated non-genetic risk factors with modifications of the stress response and the immune system. Finally, we point to the urgent need for further genome-wide analyses and the integration of genetic and epigenetic information to understand individual differences in reactive and proactive AB. © 2015 Wiley Periodicals, Inc.

The dimensional nature of eating pathology: Evidence from a direct comparison of categorical, dimensional, and hybrid models

Eating disorders are conceptualized as categorical rather than dimensional in the current major diagnostic system (Diagnostic and Statistical Manual of Mental Disorders; 5th ed.; American Psychiatric Association, 2013) and in many previous studies. However, previous research has not critically evaluated this assumption or tested hybrid models (e.g., modeling latent variables with both dimensional and categorical features). Accordingly, the current study directly compared categorical, dimensional, and hybrid models for eating pathology in a large, population-based sample. Participants included 3,032 female and male twins (ages 9-30 years) from the Michigan State University Twin Registry. The Minnesota Eating Behaviors Survey was used to assess disordered eating symptoms including body dissatisfaction, weight preoccupation, binge eating, and compensatory behaviors. Results showed that dimensional models best fit the data in the overall sample as well as across subgroups divided by sex and pubertal status (e.g., prepubertal vs. postpubertal). It is interesting to note that the results favored more categorical models when using a case-control subset of our sample with participants who either endorsed substantial eating pathology or no/little eating pathology. Overall, findings provide support for a dimensional conceptualization of eating pathology and underscore the importance of using community samples to capture the full range of severity of eating pathology when investigating questions about taxonomy. (PsycINFO Database Record

Personality Traits Predict the Developmental Course of Externalizing: A Four-Wave Longitudinal Study Spanning Age 17 to Age 29

The objective of the present study was to determine whether and how personality predicts the developmental course of externalizing problems, including antisocial behavior and substance dependence. In a large, population-based longitudinal study (N = 1,252), the 11 personality traits assessed by the Multidimensional Personality Questionnaire were measured at age 17, and DSM diagnoses of adult antisocial behavior, alcohol dependence, and drug dependence were obtained at ages 17, 20, 24, and 29. We fit a quadratic multiple indicator latent growth model where the three diagnoses loaded onto an externalizing factor. This model fit the data well, and externalizing increased until it started to decline at age 24. High aggression and low control were the most significant predictors of the development of externalizing, with aggression playing a significant role in the development of externalizing across the 12-year time span, and control predicting the development from age 17 to 24. The findings highlight the importance of considering the developmental course of externalizing in the context of personality and suggest that the specific personality traits of aggression and control might be targeted in externalizing prevention and intervention programs.

Dependence of Gene-by-Environment Interactions (GxE) on Scaling: Comparing the Use of Sum Scores, Transformed Sum Scores and IRT Scores for the Phenotype in Tests of GxE

Estimates of gene-environment interactions (GxE) in behavior genetic models depend on how a phenotype is scaled. Inappropriately scaled phenotypes result in biased estimates of GxE and can sometimes even suggest GxE in the direction opposite to its true direction. Previously proposed solutions are mathematically complex, computationally demanding and may prove impractical for the substantive researcher. We, therefore, evaluated two simple-to-use alternatives: (1) straightforward non-linear transformation of sum scores and (2) factor scores from an appropriate item response theory (IRT) model. Within Purcell's (2002) GxM framework, both alternatives provided less biased parameter estimates, and improved false and true positive rates than using a raw sum score. These approaches are, therefore, recommended over using raw sum scores in tests of GxE. Circumstances under which IRT factor scores versus transformed sum scores should be preferred are discussed.

Identifying an efficient set of items sensitive to clinical-range externalizing problems in children

The present study applied item response theory to identify an efficient set of items of the Achenbach Externalizing scale from the Child Behavior Checklist (CBCL; 33 items) and Teacher's Report Form (TRF; 35 items) that were sensitive to clinical-range scores. Mothers and teachers rated children's externalizing problems annually from ages 5 to 13 years in 2 independent samples (Ns = 585 and 1,199). Item properties for each rater across ages 5-8 and 9-13 were examined with item response theory. We identified 10 mother- and teacher-reported items from both samples based on the items' measurement precision for subclinical and clinical levels of externalizing problems: externalizing problems that involve meanness to others, destroying others' things, fighting, lying and cheating, attacking people, screaming, swearing/obscene language, temper tantrums, threatening people, and being loud. Scores on the scales using these items had strong reliability and psychometric properties, capturing nearly as much information as the full Externalizing scale for classifying clinical levels of externalizing problems. Scores on the scale with the 10 CBCL items had moderate accuracy, equivalent to the full Externalizing scale, in classifying diagnoses of conduct disorder based on a research diagnostic interview. Of course, comprehensive clinical assessment would consider additional items, dimensions of behavior, and sources of information, too, but it appears that the behaviors tapped by this select set of items may be core to externalizing psychopathology in children. (PsycINFO Database Record

Denoting treatment outcome in child and adolescent psychiatry: a comparison of continuous and categorical outcomes

Various approaches have been proposed to denote treatment outcome, such as the effect size of the pre-to-posttest change, percentage improvement, statistically reliable change, and clinical significant change. The aim of the study is to compare these approaches and evaluate their aptitude to differentiate among child and adolescent mental healthcare providers regarding their treatment outcome. Comparing outcomes according to continuous and categorical outcome indicators using real-life data of seven mental healthcare providers, three using the Child Behavior Checklist and four using the Strengths and Difficulties Questionnaire as primary outcome measure. Within each dataset consistent differences were found between providers and the various methods led to comparable rankings of providers. Statistical considerations designate continuous outcomes as the optimal choice. Change scores have more statistical power and allow for a ranking of providers at first glance. Expressing providers' performance in proportions of recovered, changed, unchanged, or deteriorated patients has supplementary value, as it denotes outcome in a manner more easily interpreted and appreciated by clinicians, managerial staff, and, last but not least, by patients or their parents.

Disorders without borders: current and future directions in the meta-structure of mental disorders

PURPOSE

Classification is the cornerstone of clinical diagnostic practice and research. However, the extant psychiatric classification systems are not well supported by research evidence. In particular, extensive comorbidity among putatively distinct disorders flags an urgent need for fundamental changes in how we conceptualize psychopathology. Over the past decade, research has coalesced on an empirically based model that suggests many common mental disorders are structured according to two correlated latent dimensions: internalizing and externalizing.

METHODS

We review and discuss the development of a dimensional-spectrum model which organizes mental disorders in an empirically based manner. We also touch upon changes in the DSM-5 and put forward recommendations for future research endeavors.

RESULTS

Our review highlights substantial empirical support for the empirically based internalizing-externalizing model of psychopathology, which provides a parsimonious means of addressing comorbidity.

CONCLUSIONS

As future research goals, we suggest that the field would benefit from: expanding the meta-structure of psychopathology to include additional disorders, development of empirically based thresholds, inclusion of a developmental perspective, and intertwining genomic and neuroscience dimensions with the empirical structure of psychopathology.

Transdiagnostic factors of psychopathology and substance use disorders: a review

PURPOSE

Research on the structure of mental disorders and comorbidity indicates that many forms of psychopathology and substance use disorders are manifestations of relatively few transdiagnostic latent factors. These factors have important consequences for mental disorder research and applied practice.

METHODS

We provide an overview of the transdiagnostic factor literature, with particular focus on recent advances.

RESULTS

Internalizing and externalizing transdiagnostic factors have been well characterized in terms of their structures, links with disorders, stability, and statistical properties (e.g., invariance and distributions). Research on additional transdiagnostic factors, such as thought disorder, is quickly advancing latent structural models, as are integrations of transdiagnostic constructs with personality traits. Genetically informed analyses continue to clarify the origins of transdiagnostic factor levels, and links between these factors and important environmental exposures provide promising new avenues of inquiry.

CONCLUSIONS

Transdiagnostic factors account for the development and continuity of disorders and comorbidity over time, function as the primary links between disorders and important outcomes such as suicide, mediate associations between environmental exposures and disorders, provide an empirically supported classification system, and serve as foci for efficient, broadband intervention approaches. Overall, transdiagnostic factor research indicates the paramount importance of understanding these constructs and, thereby, broadening our understanding of mental disorder in general.

Effects of minimum legal drinking age on alcohol and marijuana use: evidence from toxicological testing data for fatally injured drivers aged 16 to 25 years

Background

Alcohol and marijuana are among the most commonly used drugs by adolescents and young adults. The question of whether these two drugs are substitutes or complements has important implications for public policy and prevention strategies, especially as laws regarding the use of marijuana are rapidly changing.

Methods

Data were drawn from fatally injured drivers aged 16 to 25 who died within 1 h of the crash in nine states with high rates of toxicology testing based from 1999 to 2011 on the Fatality Analysis Reporting System (N = 7,191). Drug tests were performed using chromatography and radioimmunoassay techniques based on blood and/or urine specimens. Relative risk regression and Joinpoint permutation analysis were used.

Results

Overall, 50.5% of the drivers studied tested positive for alcohol or marijuana. Univariable relative risk modeling revealed that reaching the minimum legal drinking age was associated with a 14% increased risk of alcohol use (RR = 1.14, 95% CI: 1.02 to 1.28), a 24% decreased risk of marijuana use (RR = 0.76, 95% CI: 0.53 to 1.10), and a 22% increased risk of alcohol plus marijuana use (RR=1.22, 95% CI: 0.90 to 1.66). Joinpoint permutation analysis indicated that the prevalence of alcohol use by age is best described by two slopes, with a change at age 21. There was limited evidence for a change at age 21 for marijuana use.

Conclusions

These results suggest that among adolescents and young adults, increases in alcohol availability after reaching the MLDA have marginal effect on marijuana use.

The diagnostic utility of separation anxiety disorder symptoms: an item response theory analysis

At present, it is not clear whether the current definition of separation anxiety disorder (SAD) is the optimal classification of developmentally inappropriate, severe, and interfering separation anxiety in youth. Much remains to be learned about the relative contributions of individual SAD symptoms for informing diagnosis. Two-parameter logistic Item Response Theory analyses were conducted on the eight core SAD symptoms in an outpatient anxiety sample of treatment-seeking children (N = 359, 59.3 % female, M Age = 11.2) and their parents to determine the diagnostic utility of each of these symptoms. Analyses considered values of item threshold, which characterize the SAD severity level at which each symptom has a 50 % chance of being endorsed, and item discrimination, which characterize how well each symptom distinguishes individuals with higher and lower levels of SAD. Distress related to separation and fear of being alone without major attachment figures showed the strongest discrimination properties and the lowest thresholds for being endorsed. In contrast, worry about harm befalling attachment figures showed the poorest discrimination properties, and nightmares about separation showed the highest threshold for being endorsed. Distress related to separation demonstrated crossing differential item functioning associated with age-at lower separation anxiety levels excessive fear at separation was more likely to be endorsed for children ≥9 years, whereas at higher levels this symptom was more likely to be endorsed by children <9 years. Implications are discussed for optimizing the taxonomy of SAD in youth.

Describing and predicting developmental profiles of externalizing problems from childhood to adulthood

This longitudinal study considers externalizing behavior problems from ages 5 to 27 (N = 585). Externalizing problem ratings by mothers, fathers, teachers, peers, and self-report were modeled with growth curves. Risk and protective factors across many different domains and time frames were included as predictors of the trajectories. A major contribution of the study is in demonstrating how heterotypic continuity and changing measures can be handled in modeling changes in externalizing behavior over long developmental periods. On average, externalizing problems decreased from early childhood to preadolescence, increased during adolescence, and decreased from late adolescence to adulthood. There was strong nonlinear continuity in externalizing problems over time. Family process, peer process, stress, and individual characteristics predicted externalizing problems beyond the strong continuity of externalizing problems. The model accounted for 70% of the variability in the development of externalizing problems. The model's predicted values showed moderate sensitivity and specificity in prediction of arrests, illegal drug use, and drunk driving. Overall, the study showed that by using changing, developmentally relevant measures and simultaneously taking into account numerous characteristics of children and their living situations, research can model lengthy spans of development and improve predictions of the development of later, severe externalizing problems.

ADHD and the externalizing spectrum: direct comparison of categorical, continuous, and hybrid models of liability in a nationally representative sample

PURPOSE

Alcohol use disorders, substance use disorders, and antisocial personality disorder share a common externalizing liability, which may also include attention-deficit hyperactivity disorder (ADHD). However, few studies have compared formal quantitative models of externalizing liability, with the aim of delineating the categorical and/or continuous nature of this liability in the community. This study compares categorical, continuous, and hybrid models of externalizing liability.

METHOD

Data were derived from the 2004-2005 National Epidemiologic Survey on Alcohol and Related Conditions (N = 34,653). Seven disorders were modeled: childhood ADHD and lifetime diagnoses of antisocial personality disorder (ASPD), nicotine dependence, alcohol dependence, marijuana dependence, cocaine dependence, and other substance dependence.

RESULTS

The continuous latent trait model provided the best fit to the data. Measurement invariance analyses supported the fit of the model across genders, with females displaying a significantly lower probability of experiencing externalizing disorders. Cocaine dependence, marijuana dependence, other substance dependence, alcohol dependence, ASPD, nicotine dependence, and ADHD provided the greatest information, respectively, about the underlying externalizing continuum.

CONCLUSIONS

Liability to externalizing disorders is continuous and dimensional in severity. The findings have important implications for the organizational structure of externalizing psychopathology in psychiatric nomenclatures.

Comorbidity of anxiety and depression in children and adolescents: 20 years after

Brady and Kendall (1992) concluded that although anxiety and depression in youths are meaningfully linked, there are important distinctions, and additional research is needed. Since then, studies of anxiety-depression comorbidity in youths have increased exponentially. Following a discussion of comorbidity, we review existing conceptual models and propose a multiple pathways model to anxiety-depression comorbidity. Pathway 1 describes youths with a diathesis for anxiety, with subsequent comorbid depression resulting from anxiety-related impairment. Pathway 2 refers to youths with a shared diathesis for anxiety and depression, who may experience both disorders simultaneously. Pathway 3 describes youths with a diathesis for depression, with subsequent comorbid anxiety resulting from depression-related impairment. Additionally, shared and stratified risk factors contribute to the development of the comorbid disorder, either by interacting with disorder-related impairment or by predicting the simultaneous development of the disorders. Our review addresses descriptive and developmental factors, gender differences, suicidality, assessments, and treatment-outcome research as they relate to comorbid anxiety and depression and to our proposed pathways. Research since 1992 indicates that comorbidity varies depending on the specific anxiety disorder, with Pathway 1 describing youths with either social phobia or separation anxiety disorder and subsequent depression, Pathway 2 applying to youths with coprimary generalized anxiety disorder and depression, and Pathway 3 including depressed youths with subsequent social phobia. The need to test the proposed multiple pathways model and to examine (a) developmental change and (b) specific anxiety disorders is highlighted.

Transdiagnostic and disorder-specific models of intergenerational transmission of internalizing pathology

BACKGROUND

Numerous studies have supported an association between maternal depression and child psychiatric outcomes, but few have controlled for the confounding effects of both maternal and offspring co-morbidity. Thus, it remains unclear whether the correspondence between maternal and offspring depressive and anxiety disorders is better explained by associations between shared features of maternal and offspring internalizing disorders or by specific effects exerted by unique aspects of individual disorders.

METHOD

Pairs of mothers and offspring overselected for maternal depression (n = 815) were assessed at offspring age 15 years for anxiety and depressive disorders; 705 completed a follow-up at offspring age 20 years. For both mothers and offspring, structural equation modeling was used to distinguish transdiagnostic internalizing pathology--representing the overlap among all depressive and anxiety disorders--from diagnosis-specific forms of pathology. To discriminate between general versus specific pathways of intergenerational transmission of psychopathology, we examined (a) the general association between the maternal and offspring internalizing factors and (b) the correlations between maternal and offspring diagnosis-specific pathology for each disorder.

RESULTS

For mothers and offspring, a unidimensional latent variable model provided the best fit to the correlations among depressive and anxiety disorders. The maternal transdiagnostic internalizing factor strongly predicted the corresponding factor among offspring. In addition, the unique component of post-traumatic stress disorder among offspring was significantly related to the analogous unique component among mothers, but specific components of other maternal disorders, including depression, did not predict corresponding offspring pathology.

CONCLUSIONS

Results suggest that intergenerational transmission of internalizing disorders is largely non-specific.

Toward a model-based approach to the clinical assessment of personality psychopathology

Recent years have witnessed tremendous growth in the scope and sophistication of statistical methods available to explore the latent structure of psychopathology, involving continuous, discrete, and hybrid latent variables. The availability of such methods has fostered optimism that they can facilitate movement from classification primarily crafted through expert consensus to classification derived from empirically based models of psychopathological variation. The explication of diagnostic constructs with empirically supported structures can then facilitate the development of assessment tools that appropriately characterize these constructs. Our goal in this article is to illustrate how new statistical methods can inform conceptualization of personality psychopathology and therefore its assessment. We use magical thinking as an example, because both theory and earlier empirical work suggested the possibility of discrete aspects to the latent structure of personality psychopathology, particularly forms of psychopathology involving distortions of reality testing, yet other data suggest that personality psychopathology is generally continuous in nature. We directly compared the fit of a variety of latent variable models to magical thinking data from a sample enriched with clinically significant variation in psychotic symptomatology for explanatory purposes. Findings generally suggested a continuous latent variable model best represented magical thinking, but results varied somewhat depending on different indexes of model fit. We discuss the implications of the findings for classification and applied personality assessment. We also highlight some limitations of this type of approach that are illustrated by these data, including the importance of substantive interpretation, in addition to use of model fit indexes, when evaluating competing structural models.

Cross-informant agreement on child and adolescent withdrawn behavior: a latent class approach

Withdrawn behavior (WB) relates to many developmental outcomes, including pervasive developmental disorders, anxiety, depression, psychosis, personality disorders and suicide. No study has compared the latent profiles of different informants' reports on WB. This study uses multi-informant latent class analyses (LCA) of the child behavior checklist (CBCL), teacher report form (TRF) and youth self-report (YSR) to examine phenotypic variance in WB. LCA was applied to the CBCL, TRF and YSR of 2,031 youth (ages 6-18); of which 276 children were clinically-referred. A 4-class solution for the CBCL and 3-class solutions for the YSR and TRF were optimal. The CBCL yielded low symptoms, predominantly shy or secretive moderate symptoms, and all symptoms classes. The TRF lacked the moderate--secretive class, and the YSR lacked the moderate--shy class. Agreement was low. LCA shows similar structure of withdrawn behavior across informants but characterizations of moderate WB vary.

A Five-Factor Model framework for understanding childhood personality disorder antecedents

The present contribution reviews evidence that supports the relevance of childhood antecedents of personality disorders, and advocates that the validity of a Five-Factor Model framework for describing general trait differences in childhood can be extended towards the field of developmental personality difficulties. In addition, we suggest that several traditional childhood Axis I conditions include a substantial trait component that may be responsible for the recurring finding that childhood Axis I disorders are predictive for adult Axis II disorders. Given the valuable information provided by a trait assessment, we further propose to integrate dimensional personality and personality pathology measures as standard tools in mental health assessments at a young age.

A longitudinal assessment of the associations among response access, attention problems, and aggression during childhood

Children with ADHD symptoms often display social competence deficits, yet mechanisms for their social difficulties remain unclear. Using data from the normative sample of non-intervention respondents (N = 387; 50 % male; 49 % non-European-American; age at initial assessment: M = 6.5 years, SD = 0.48) in the Fast Track project (Lochman and CPPRG Journal of Consulting and Clinical Psychology 63:549-59, 1995), the social-information processing ability of accessing responses for social situations was modeled across four time points from kindergarten to third grade. Teacher-rated aggression and ADHD symptoms were included as predictors of the intercept and slope. Low ADHD symptoms were associated with a decline in aggressive responses across childhood, whereas high ADHD symptoms were linked to an increase in aggressive responses that decelerated between second and third grade. Regarding competent responses, low ADHD symptoms predicted increases in competent responses, but this increase decelerated between second and third grade. High ADHD symptoms were also associated with a slight increase in competent responses into first grade, but competent responses decreased from first to third grade. Neither aggression nor the interaction of ADHD symptoms and aggression accounted for a significant amount of variance in aggressive or competent responses. Future research should identify if differences in response access associated with high and low ADHD symptoms link to difficulties making and keeping friendships.

Ethnicity and psychiatric comorbidity in a national sample: evidence for latent comorbidity factor invariance and connections with disorder prevalence

PURPOSE

Prevalence rates, and bivariate comorbidity patterns, of many common mental disorders differ significantly across ethnic groups. While studies have examined multivariate comorbidity patterns by gender and age, no studies to our knowledge have examined such patterns by ethnicity. Such an investigation could aid in understanding the nature of ethnicity-related health disparities in mental health and is timely given the likely implementation of multivariate comorbidity structures (i.e., internalizing and externalizing) to frame key parts of DSM-5.

METHODS

We investigated whether multivariate comorbidity of 11 common mental disorders, and their associated latent comorbidity factors, differed across five ethnic groups in a large, nationally representative sample (n = 43,093). We conducted confirmatory factor analyses and factorial invariance analyses in White (n = 24,507), Hispanic/Latino (n = 8,308), Black (n = 8,245), Asian/Pacific Islander (n = 1,332), and American Indian/Alaska Native (n = 701) individuals.

RESULTS

Results supported a two-factor internalizing-externalizing comorbidity factor model in both lifetime and 12-month diagnoses. This structure was invariant across ethnicity, but factor means differed significantly across ethnic groups.

CONCLUSIONS

These findings, taken together, indicated that observed prevalence rate differences between ethnic groups reflect ethnic differences in latent internalizing and externalizing factor means. We discuss implications for classification (DSM-5 and ICD-11 meta-structure), health disparities research, and treatment.

Evidence for a multi-dimensional latent structural model of externalizing disorders

Strong associations between conduct disorder (CD), antisocial personality disorder (ASPD) and substance use disorders (SUD) seem to reflect a general vulnerability to externalizing behaviors. Recent studies have characterized this vulnerability on a continuous scale, rather than as distinct categories, suggesting that the revision of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) take into account the underlying continuum of externalizing behaviors. However, most of this research has not included measures of disorders that appear in childhood [e.g., attention-deficit/hyperactivity disorder (ADHD) or oppositional defiant disorder (ODD)], nor has it considered the full range of possibilities for the latent structure of externalizing behaviors, particularly factor mixture models, which allow for a latent factor to have both continuous and categorical dimensions. Finally, the majority of prior studies have not tested multidimensional models. Using lifetime diagnoses of externalizing disorders from participants in the Fast Track Project (n = 715), we analyzed a series of latent variable models ranging from fully continuous factor models to fully categorical mixture models. Continuous models provided the best fit to the observed data and also suggested that a two-factor model of externalizing behavior, defined as (1) ODD+ADHD+CD and (2) SUD with adult antisocial behavior sharing common variance with both factors, was necessary to explain the covariation in externalizing disorders. The two-factor model of externalizing behavior was then replicated using a nationally representative sample drawn from the National Comorbidity Survey-Replication data (n = 5,692). These results have important implications for the conceptualization of externalizing disorders in DSM-5.