Where do neurodevelopmental conditions fit in transdiagnostic psychiatric frameworks? Incorporating a new neurodevelopmental spectrum.

Features of autism spectrum disorder, attention-deficit/hyperactivity disorder, learning disorders, intellectual disabilities, and communication and motor disorders usually emerge early in life and are associated with atypical neurodevelopment. These "neurodevelopmental conditions" are grouped together in the DSM-5 and ICD-11 to reflect their shared characteristics. Yet, reliance on categorical diagnoses poses significant challenges in both research and clinical settings (e.g., high co-occurrence, arbitrary diagnostic boundaries, high within-disorder heterogeneity). Taking a transdiagnostic dimensional approach provides a useful alternative for addressing these limitations, accounting for shared underpinnings across neurodevelopmental conditions, and characterizing their common co-occurrence and developmental continuity with other psychiatric conditions. Neurodevelopmental features have not been adequately considered in transdiagnostic psychiatric frameworks, although this would have fundamental implications for research and clinical practices. Growing evidence from studies on the structure of neurodevelopmental and other psychiatric conditions indicates that features of neurodevelopmental conditions cluster together, delineating a "neurodevelopmental spectrum" ranging from normative to impairing profiles. Studies on shared genetic underpinnings, overlapping cognitive and neural profiles, and similar developmental course and efficacy of support/treatment strategies indicate the validity of this neurodevelopmental spectrum. Further, characterizing this spectrum alongside other psychiatric dimensions has clinical utility, as it provides a fuller view of an individual's needs and strengths, and greater prognostic utility than diagnostic categories. Based on this compelling body of evidence, we argue that incorporating a new neurodevelopmental spectrum into transdiagnostic frameworks has considerable potential for transforming our understanding, classification, assessment, and clinical practices around neurodevelopmental and other psychiatric conditions.

Principles and procedures for revising the hierarchical taxonomy of psychopathology.

Quantitative, empirical approaches to establishing the structure of psychopathology hold promise to improve on traditional psychiatric classification systems. The Hierarchical Taxonomy of Psychopathology (HiTOP) is a framework that summarizes the substantial and growing body of quantitative evidence on the structure of psychopathology. To achieve its aims, HiTOP must incorporate emerging research in a systematic, ongoing fashion. In this article, we describe the historical context and grounding of the principles and procedures for revising the HiTOP framework. Informed by strengths and shortcomings of previous classification systems, the proposed revisions protocol is a formalized system focused around three pillars: (a) prioritizing systematic evaluation of quantitative evidence by a set of transparent criteria and processes, (b) balancing stability with flexibility, and (c) promoting inclusion over gatekeeping in all aspects of the process. We detail how the revisions protocol will be applied in practice, including the scientific and administrative aspects of the process. Additionally, we describe areas of the HiTOP structure that will be a focus of early revisions and outline challenges for the revisions protocol moving forward. The proposed revisions protocol is designed to ensure that the HiTOP framework reflects the current state of scientific knowledge on the structure of psychopathology and fulfils its potential to advance clinical research and practice. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Longitudinal Stability and Interrelations of Tonic and Phasic Irritability in Adolescent Girls.

Irritability is a transdiagnostic feature and a common mental health problem in adolescence. Prior studies indicate that irritability is composed of two correlated but separable dimensions, tonic irritability (i.e., irritable mood) and phasic irritability (i.e., temper outbursts), which are respectively associated with internalizing and externalizing outcomes. However, little is known about the stability and interrelations of tonic and phasic irritability. The current study examined the longitudinal interplay between tonic and phasic irritability during adolescence. A community sample of 544 girls (age 13.5-15.5 years) was assessed at 5 waves (over 3 years, in 9-month intervals). A random-intercept cross-lagged panel model was used to examine the within-person stability and longitudinal interrelations of tonic and phasic irritability. Pseudo-indicator models were used to help analyze all available data. Results suggest that tonic and phasic irritability had distinct patterns of development and co-development. Between individuals, tonic and phasic irritability showed moderate rank-order stability and high concurrent correlations. Within individuals, phasic irritability was found to positively predict both tonic and phasic irritability at the subsequent wave, whereas tonic irritability did not predict later phasic irritability and showed weaker within-person stability. These results suggest that increased or decreased phasic irritability in adolescent girls may signify continued increase or decrease in both tonic and phasic irritability. The study was among the first to demonstrate the discriminant validity of tonic and phasic irritability from a developmental perspective.

Linking non-suicidal self-injury to psychopathology: The utility of transdiagnostic and DSM-based models.

Non-suicidal self-injury (NSSI) is a significant public health concern, and its primary formal link to the universe of psychopathology content in DSM diagnoses has been mostly through borderline personality disorder (BPD). Recent research has produced ample evidence of weaknesses of diagnoses relative to transdiagnostic psychopathology dimensions, and found that NSSI-related variables like suicidality are best predicted by transdiagnostic versus diagnosis-based variables. These findings suggest a need to characterize how NSSI may relate to different forms of psychopathology classification constructs. We examined how transdiagnostic dimensions of psychopathology relate to NSSI, focusing on how transdiagnostic (shared) variance of dimensional psychopathology spectra might differentially explained the variance in NSSI relative to traditional DSM diagnoses. In two nationally representative United States samples (Ns = 34,653 and 36,309), we modeled the common distress-fear-externalizing transdiagnostic comorbidity model and investigated questions of predictive utility of these dimensional and categorical psychopathology structures. Transdiagnostic dimensions were superior in predicting NSSI compared to common DSM-IV and DSM-5 diagnoses. These dimensions accounted for 33.6-38.7 % of NSSI variance across all analyses in both samples. DSM-IV/DSM-5 diagnoses, however, demonstrated only modest incremental prediction of NSSI over and above the transdiagnostic dimensions. These results support a transdiagnostic reconceptualization of NSSI's links with psychopathology and highlight the importance of transdiagnostic dimensions for predicting clinical outcomes relating to self-injurious behaviors. Implications for research and clinical practice are discussed.

Gender and Racial/Ethnic Disparities in Undergraduate and Graduate Students' Mental Health and Treatment Use Amid the COVID-19 Pandemic.

The COVID-19 pandemic has negatively impacted numerous people?s mental health and created new barriers to services. To address the unknown effects of the pandemic on accessibility and equality issues in mental health care, this study aimed to investigate gender and racial/ethnic disparities in mental health and treatment use in undergraduate and graduate students amid the COVID-19 pandemic. The study was conducted based on a largescale online survey (N = 1,415) administered during the weeks following a pandemic-related university-wide campus closure in March 2020. We focused on the gender and racial disparities in current internalizing symptomatology and treatment use. Our results showed that in the initial period of the pandemic, students identified as cis women (p < .001), non-binary/genderqueer (p < .001), or Hispanic/Latinx (p = .002) reported higher internalizing problem severity (aggregated from depression, generalized anxiety, intolerance of uncertainty, and COVID-19-related stress symptoms) compared to their privileged counterparts. Additionally, Asian (p < .001) and multiracial students (p = .002) reported less treatment use than White students while controlling for internalizing problem severity. Further, internalizing problem severity was associated with increased treatment use only in cisgender, non-Hispanic/Latinx White students (pcis man = 0.040, pcis woman < 0.001). However, this relationship was negative in cis-gender Asian students (pcis man = 0.025, pcis woman = 0.016) and nonsignificant in other marginalized demographic groups. The findings revealed unique mental health challenges faced by different demographic groups and served as a call that specific actions to enhance mental health equity, such as continued mental health support for students with marginalized gender identities, additional COVID-related mental and practical support for Hispanic/Latinx students and promotion of mental health awareness, access, and trust in non-White, especially Asian, students are desperately needed.

Loneliness in Gender-Diverse and Sexual Orientation-Diverse Adolescents: Measurement Invariance Analyses and Between-Group Comparisons.

Youth loneliness is a risk factor for myriad adverse psychosocial outcomes, making it a potentially informative construct for assessment and treatment research. Minority stressors may place LGBTQ+ (lesbian, gay, bisexual, transgender, and queer) youths at high risk of loneliness. However, the prevalence of loneliness across gender and sexual identities cannot be precisely estimated or compared without establishing that common measures assess the construct equivalently across groups. In a preregistered study, we determined the optimal structure of the UCLA Loneliness Scale and investigated whether it showed invariance across gender and sexual identities in a national U.S. sample of adolescents with elevated depressive symptoms (N = 2,431; https://osf.io/52ctd). Results supported strict invariance, indicating that loneliness scores can be meaningfully compared across groups in this sample. Exploratory analyses indicated that loneliness levels and LGBTQ+ identity predicted levels of depression and anxiety. We discuss implications for research on loneliness, health disparities, and psychopathology in high-symptom youths.

Neurobiological sensitivity to unpredictable threat and familial risk for the internalizing and externalizing spectra in adolescents.

BACKGROUND: Adolescence is a key developmental period for the emergence of psychiatric disorders. However, there is still no consensus on the core mechanisms of dysfunction in youth. Neurobiological sensitivity to unpredictable threat has been associated with several psychiatric disorders in adults. The present study examined adolescent defensive motivation (startle reflex) and attention (event-related potentials) in anticipation of unpredictable threat in relation to both adolescent and maternal (i.e. familial risk) internalizing and externalizing spectra. METHODS: The sample included 395 15-year-old adolescents and their biological mothers. Adolescent startle potentiation and probe P300 suppression (indicating increased attention to threat) were measured in anticipation of predictable and unpredictable threat. Adolescent and maternal lifetime history of psychiatric disorders were assessed via semi-structured diagnostic interviews, and confirmatory factor analysis was used to model internalizing and externalizing spectra. RESULTS: The adolescent internalizing spectrum was positively associated with adolescent startle potentiation and probe P300 suppression to unpredictable threat. Conversely, the adolescent externalizing spectrum was negatively associated with adolescent P300 suppression to unpredictable threat. The maternal internalizing spectrum was positively associated with adolescent startle potentiation to unpredictable threat and P300 suppression to both predictable and unpredictable threat. The maternal externalizing spectrum was negatively associated with adolescent startle potentiation to unpredictable threat and P300 suppression to both predictable and unpredictable threat. Adolescent and maternal internalizing and externalizing spectra were independently related to adolescent startle potentiation and P300 suppression. CONCLUSIONS: Adolescent neurobiological sensitivity to unpredictable threat is associated with both personal history and familial risk for the internalizing and externalizing spectra.

Predictors of expert providers' familiarity with intervention practices for school- and transition-age youth with autism spectrum disorder.

LAY ABSTRACT: School-age children, adolescents, and young adults with autism spectrum disorder encounter many different types of providers in their pursuit of treatment for anxiety, behavior problems, and social difficulties. These providers may all be familiar with different types of intervention practices. However, research has not yet investigated patterns in expert providers' familiarity with different practices nor how these patterns are related to the characteristics of providers (years in practice, academic discipline, setting) and the youth (age and intellectual disability) they typically support. A panel of 53 expert transdisciplinary providers rated their familiarity with 55 intervention practices (derived from research and expert nominations) via an online Delphi poll. Advanced statistical methods were used to identify types of intervention practices with which providers were familiar, which included two approaches (cognitive and behavioral) and two strategies (engagement and accessibility). Providers who practiced outside a school setting or treated clients without intellectual disability were more familiar with cognitive approaches. Clinical psychologists, behavior analysts, and school-based providers were more familiar with behavioral approaches. Providers practicing outside school settings were also more familiar with engagement strategies, and providers with more years in practice were more familiar with accessibility strategies. These results may help families and researchers to better anticipate how services may vary depending on the types of autism spectrum disorder providers seen and work to reduce disparities in care that may result.

Model fit is a fallible indicator of model quality in quantitative psychopathology research: A reply to Bader and Moshagen.

As evidenced by our exchange with Bader and Moshagen (2022), the degree to which model fit indices can and should be used for the purpose of model selection remains a contentious topic. Here, we make three core points. First, we discuss the common misconception about fit statistics' abilities to identify the "best model," arguing that mechanical application of model fit indices contributes to faulty inferences in the field of quantitative psychopathology. We illustrate the consequences of this practice through examples in the literature. Second, we highlight the parsimony-adjacent concept of fitting propensity, which is not accounted for by commonly used fit statistics. Finally, we present specific strategies to overcome interpretative bias and increase generalizability of study results and stress the importance of carefully balancing substantive and statistical criteria in model selection scenarios. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

The Hierarchical Taxonomy of Psychopathology (HiTOP) in psychiatric practice and research.

The Hierarchical Taxonomy of Psychopathology (HiTOP) has emerged out of the quantitative approach to psychiatric nosology. This approach identifies psychopathology constructs based on patterns of co-variation among signs and symptoms. The initial HiTOP model, which was published in 2017, is based on a large literature that spans decades of research. HiTOP is a living model that undergoes revision as new data become available. Here we discuss advantages and practical considerations of using this system in psychiatric practice and research. We especially highlight limitations of HiTOP and ongoing efforts to address them. We describe differences and similarities between HiTOP and existing diagnostic systems. Next, we review the types of evidence that informed development of HiTOP, including populations in which it has been studied and data on its validity. The paper also describes how HiTOP can facilitate research on genetic and environmental causes of psychopathology as well as the search for neurobiologic mechanisms and novel treatments. Furthermore, we consider implications for public health programs and prevention of mental disorders. We also review data on clinical utility and illustrate clinical application of HiTOP. Importantly, the model is based on measures and practices that are already used widely in clinical settings. HiTOP offers a way to organize and formalize these techniques. This model already can contribute to progress in psychiatry and complement traditional nosologies. Moreover, HiTOP seeks to facilitate research on linkages between phenotypes and biological processes, which may enable construction of a system that encompasses both biomarkers and precise clinical description.

Answering questions about the Hierarchical Taxonomy of Psychopathology (HiTOP): Analogies to whales and sharks miss the boat.

This commentary discusses questions and misconceptions about HiTOP raised by Haeffel et al. (2021). We explain what the system classifies and why it is descriptive and atheoretical, highlighting benefits and limitations of this approach. We clarify why the system is organized according to patterns of covariation or comorbidity among signs and symptoms of psychopathology, and we discuss how it is designed to be falsifiable and revised in a manner that is responsive to data. We refer to the body of evidence for HiTOP's external validity and for its scientific and clinical utility. We further describe how the system is currently used in clinics. In sum, many of Haeffel et al.'s concerns about HiTOP are unwarranted, and for those concerns that reflect real current limitations of HiTOP, our consortium is working to address them, with the aim of creating a nosology that is comprehensive and useful to both scientists and clinicians.

Misbegotten methodologies and forgotten lessons from Tom Swift's electric factor analysis machine: A demonstration with competing structural models of psychopathology.

Confirmatory factor analysis (CFA) and its bifactor models are popular in empirical investigations of the factor structure of psychological constructs. CFA offers straightforward hypothesis testing but has notable pitfalls, such as the imposition of strict assumptions (i.e., simple structure) that obscure unmodeled complexity. Due to the limitations of bifactor CFAs, they have yielded anomalous results across samples and studies that suggest model misspecification (e.g., evaporating specific factors and unexpected loadings). We propose the use of exploratory factor analysis (EFA) to evaluate the structural validity of CFA solutions-either before or after the estimation of more restrictive CFA models-to (a) identify model misspecifications that may drive anomalous estimates and (b) confirm CFA models by examining whether hypothesized structures emerge with limited researcher input. We evaluated the degree to which predominant factor structures were invariant across contexts along the exploratory-confirmatory continuum and demonstrate how poor methodological choices can distort results and impede theory development. All CFA models fit well, but there were numerous differences in replicability and substantive interpretability. Several similarities emerged between bifactor CFA and EFA models, including evidence of overextraction, the collapse of specific factors onto the general factor, and subsequent shifts in how the general factor was defined. We situate these methodological shortcomings within the broader literature on structural models of psychopathology, articulate implications for theories (such as the p-factor) that are borne out of factor analysis, outline several remedies for problems encountered when performing exploratory bifactor analysis, and propose alternative specifications for confirmatory bifactor models. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

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.

Bullying Perpetration and Victimization in Youth: Associations with Irritability and Anxiety.

Prior work on has demonstrated that irritability and anxiety are associated with bullying perpetration and victimization, respectively. Even though symptoms of irritability and anxiety often occur concurrently, few studies have tested their interactive effects on perpetration or victimization. The current study recruited 131 youths from a broader program of research that examines the pathophysiology and treatment of pediatric irritability and anxiety. Two moderation tests were performed to examine concurrent irritability and anxiety symptoms and their relation to perpetration and victimization of bullying. More severe anxiety was associated with greater victimization. However, more severe irritability was associated with, not just greater perpetration, but also greater victimization. An irritability-by-anxiety interaction demonstrated that youths with more severe irritability and lower levels of anxiety engaged in more perpetration. Our findings suggest a more nuanced approach to understanding how the commonly comorbid symptoms of irritability and anxiety interact in relation to peer-directed behavior in youths.

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.

Internalizing psychopathology and all-cause mortality: a comparison of transdiagnostic vs. diagnosis-based risk prediction.

Previous studies have documented the utility of a transdiagnostic internalizing factor in predicting important future outcomes (e.g., subsequent mental disorder diagnoses). To date, however, no study has investigated whether an internalizing factor predicts mortality risk. Also, while pre-vious studies of mortality risk have emphasized its associations with particular internalizing disorders, no study has assessed how the transdiagnostic internalizing factor vs. disorder-specific variance differently predict that risk. The primary aims of this study were to explore: a) whether the internalizing factor predicts mortality risk, b) whether particular internalizing psychopathologies uniquely predict mortality risk over and beyond the transdiagnostic internalizing factor, and c) whether there is a significant interaction of internalizing with self-reported health in the prediction of mortality risk. We utilized a large national sample of American adults from the Midlife in the United States (MIDUS), a longitudinal study that examined midlife development of individuals across multiple waves between 1995 and 2015. Data were analyzed for the 6,329 participants who completed the phone interview and self-administered questionnaire in MIDUS 1 (1995-1996) and were then followed up until October 31, 2015 or until death. To investigate the association between internalizing and mortality risk, we used the semi-parametric proportional hazards Cox model, where survival time was regressed on a latent internalizing factor. Overall findings indicate that a transdiagnostic internalizing factor significantly predicts mortality risk over a 20-year period (hazard ratio, HR=1.12, 95% CI: 1.05-1.16, p<0.01) and that internalizing outperforms disorder-specific variance (e.g., depression-specific variance) in the prediction of that risk. Further, there was a significant interaction between transdiagnostic internalizing and self-reported health, whereby internalizing psychopathology had a specific association with early death for individuals with excellent self-reported health condition (HR=1.50, 95% CI: 1.17-1.84, p<0.05). This highlights the clinical utility of using the transdiagnostic internalizing factor for prediction of an important future outcome, and supports the argument that internalizing psychopathology can be a meaningful liability to explore in public health practice.

Validity and utility of Hierarchical Taxonomy of Psychopathology (HiTOP): II. Externalizing superspectrum.

The Hierarchical Taxonomy of Psychopathology (HiTOP) is an empirical effort to address limitations of traditional mental disorder diagnoses. These include arbitrary boundaries between disorder and normality, disorder co-occurrence in the modal case, heterogeneity of presentation within dis-orders, and instability of diagnosis within patients. This paper reviews the evidence on the validity and utility of the disinhibited externalizing and antagonistic externalizing spectra of HiTOP, which together constitute a broad externalizing superspectrum. These spectra are composed of elements subsumed within a variety of mental disorders described in recent DSM nosologies, including most notably substance use disorders and "Cluster B" personality disorders. The externalizing superspectrum ranges from normative levels of impulse control and self-assertion, to maladaptive disinhibition and antagonism, to extensive polysubstance involvement and personality psychopathology. A rich literature supports the validity of the externalizing superspectrum, and the disinhibited and antagonistic spectra. This evidence encompasses common genetic influences, environmental risk factors, childhood antecedents, cognitive abnormalities, neural alterations, and treatment response. The structure of these validators mirrors the structure of the phenotypic externalizing superspectrum, with some correlates more specific to disinhibited or antagonistic spectra, and others relevant to the entire externalizing superspectrum, underlining the hierarchical structure of the domain. Compared with traditional diagnostic categories, the externalizing superspectrum conceptualization shows improved utility, reliability, explanatory capacity, and clinical applicability. The externalizing superspectrum is one aspect of the general approach to psychopathology offered by HiTOP and can make diagnostic classification more useful in both research and the clinic.

Substance use in a sexual context: The association of sex-related substance use motives with substance choice and use behaviors.

BACKGROUND: Substance use before sex is associated with riskier behaviors. Sex-related substance use motives may explain pre-sex substance use. We explored what sex-related motives are associated with alcohol versus drug use, and which motives underlie heavier use. METHODS: A sample of 936 participants (50% male, 80% White) completed an Internet survey about sexuality. Those who drank before sex (n=657) reported on six sex-related drinking motives; those who used drugs before sex (n=271) reported on six (parallel) sex-related drug use motives. The frequency of endorsement of each motive between drinkers and drug users was compared with z-distributions. Logistic regressions assessed whether motives were associated with substance use frequency and intoxication before sex. RESULTS: Substance use to relax and to get a sex partner to use were more commonly endorsed for alcohol than drugs; substance use to improve performance and enhance experience were more commonly endorsed for drugs. Most motives were associated with alcohol frequency and intoxication before sex. None were associated with drug frequency; some were associated with drug intoxication. CONCLUSIONS: Alcohol was generally used to facilitate sex, and drugs to enhance sex. Sex-related drinking motives were associated with drinking before sex; sex-related drug use motives were less predictive.

The Hierarchical Taxonomy of Psychopathology (HiTOP): A Quantitative Nosology Based on Consensus of Evidence.

Traditional diagnostic systems went beyond empirical evidence on the structure of mental health. Consequently, these diagnoses do not depict psychopathology accurately, and their validity in research and utility in clinicalpractice are therefore limited. The Hierarchical Taxonomy of Psychopathology (HiTOP) consortium proposed a model based on structural evidence. It addresses problems of diagnostic heterogeneity, comorbidity, and unreliability. We review the HiTOP model, supporting evidence, and conceptualization of psychopathology in this hierarchical dimensional framework. The system is not yet comprehensive, and we describe the processes for improving and expanding it. We summarize data on the ability of HiTOP to predict and explain etiology (genetic, environmental, and neurobiological), risk factors, outcomes, and treatment response. We describe progress in the development of HiTOP-based measures and in clinical implementation of the system. Finally, we review outstanding challenges and the research agenda. HiTOP is of practical utility already, and its ongoing development will produce a transformative map of psychopathology.

Three recommendations based on a comparison of the reliability and validity of the predominant models used in research on the empirical structure of psychopathology.

The present study compared the primary models used in research on the structure of psychopathology (i.e., correlated factor, higher-order, and bifactor models) in terms of structural validity (model fit and factor reliability), longitudinal measurement invariance, concurrent and prospective predictive validity in relation to important outcomes, and longitudinal consistency in individuals' factor score profiles. Two simpler operationalizations of a general factor of psychopathology were also examined-a single-factor model and a count of diagnoses. Models were estimated based on structured clinical interview diagnoses in two longitudinal waves of nationally representative data from the United States (n = 43,093 and n = 34,653). Models that included narrower factors (fear, distress, and externalizing) were needed to capture the observed multidimensionality of the data. In the correlated factor and higher-order models these narrower factors were reliable, largely invariant over time, had consistent associations with indicators of adaptive functioning, and had moderate stability within individuals over time. By contrast, the fear- and distress-specific factors in the bifactor model did not show good reliability or validity throughout the analyses. Notably, the general factor of psychopathology (p factor) performed similarly well across tests of reliability and validity regardless of whether the higher-order or bifactor model was used; the simplest (single factor) model was also comparable across most tests, with the exception of model fit. Given the limitations of categorical diagnoses, it will be important to repeat these analyses using dimensional measures. We conclude that when aiming to understand the structure and correlates of psychopathology it is important to (a) look beyond model fit indices to choose between different models, (b) examine the reliability of latent variables directly, and (c) be cautious when isolating and interpreting the unique effects of specific psychopathology factors, regardless of which model is used. (PsycInfo Database Record (c) 2021 APA, all rights reserved).