Looking at HiTOP

I’ve written before Hierarchical Taxonomy of Psychopathology (HiTOP) framework before, but am revisiting it today with new theory and research. First, Trayvick, Adams & Nelson (2024) published “The P300 and Hierarchical Dimensions of Psychopathology” in Journal of Psychopathology and Clinical Science. Here’s the edited abstract and impact statement:

The Hierarchical Taxonomy of Psychopathology (HiTOP) framework offers the potential to better understand how neurobiological mechanisms relate to psychopathology. The P300 is an event-related potential component that indexes attention, stimulus evaluation, and categorization. A blunted P300 has been associated with psychiatric disorders across externalizing, internalizing, and thought disorder domains. However, there has been little research investigating whether the P300 is related to higher-order dimensions of psychopathology. In a sample of 225 adults aged 18–35 years (Mage = 23.09, SD = 3.83, 82.2% female) who were oversampled for psychopathology, the present study examined the associations between the P300 and both psychopathology spectra and a general factor. Participants completed multiple experimental tasks, while electroencephalography was recorded to measure the P300 elicited by auditory, tactile, and visual stimuli. Participants also completed the self-report Comprehensive Assessment of Traits Relevant to Personality Disorder to assess pathological personality dimensions. We used structural equation modeling to examine the relationship between a latent P300 factor and both psychopathology spectra (negative emotionality, detachment, psychoticism, disinhibition, and antagonism) and a general factor. The results indicated that the P300 was inversely related to the general factor. Further analyses revealed no relationships between the P300 and any individual spectrum when accounting for the general factor. The study also demonstrates the potential importance of neuroscience-informed dimensional systems to understand clinical phenomena. 

The Hierarchical Taxonomy of Psychopathology provides a framework to investigate the relationship between neurobiological mechanisms, such as the P300, and multiple levels of psychopathology. A blunted P300 has been associated with many psychiatric disorders, which indicates that it might relate to higher-order dimensions of psychopathology. The present study suggests that the P300 is an indicator of the general factor of psychopathology as opposed to lower-order dimensions.

What’s important here is the attempt to use neurobiological evidence to better understand psychopathology. Here we see that a blunted P300 indicates a general factor of psychopathology. The next study looks at the potential value of HiTOP. Morris, Michelini & Wilson (2025) published “Moving Toward Transdiagnostic Dimensional Models of Neurodiversity and Mental Health (and Away from Models of Psychopathology)” in Journal of Psychopathology and Clinical Science. Here’s the edited abstract:

This article discusses the transdiagnostic dimensional models of neurodiversity and mental health. Moving toward transdiagnostic dimensional models of neurodiversity and mental health—rather than dimensional models of psychopathology—embraces neurodiversity as human diversity and destigmatizes neurodivergence. Individuals with neurodevelopmental conditions do not need to be “cured” of neurodivergence as pathology, but the inclusion of neurodevelopmental conditions in transdiagnostic dimensional models does recognize the high co-occurrence of different neurodevelopmental conditions with each other and with mental health concerns and increases access to appropriate and needed supports to improve well-being across the lifespan. Increasing recognition that neurodiversity is part of human diversity prompts reconsideration of the current dominant conceptualization of neurodivergence as inherently atypical or pathological. “Neurodiversity” refers to the tremendous range of possible variations in brain function, neurocognition, and behavior—no two brains or minds function in exactly the same way. “Neurodivergent,” often contrasted with “neurotypical,” refers to a brain or mind that functions in a way that deviates from culturally normative expectations. Neurodivergence may manifest in different ways and to varying degrees—and be more or less adaptive at different times, in different contexts, or from different perspectives. “Neurodevelopmental conditions” are characterized by neurodivergence, including early-arising differences that affect cognition, motor function, sensation, perception, and/or communication and are currently included in the Diagnostic and Statistical Manual of Mental Disorders, fifth edition in the “Neurodevelopmental Disorders” chapter. The authors propose a distinction between neurodevelopmental conditions and mental health conditions such that DSM neurodevelopmental disorders should no longer be subsumed under the mental disorder classification but instead reclassified alongside them, resulting in the Diagnostic and Statistical Manual of Neurodevelopmental and Mental Disorders. 

I like the notion of destigmatizing neurodivergence and clarifying the distinction between neurodevelopmental and mental disorders. Bottesi, Caudek, Colpizzi, Iannattone, Palmieri & Sica (2024) published “Advancing Understanding of the Relation between Criterion A of the Alternative Model for personality Disorders and Hierarchical Taxonomy of Psychopathology: Insights from an external validity analysis” in Personality Disorders: Theory, Research, and Treatment. The edited abstract follows:

Increasing interest surrounds the relation between Level of Personality Functioning (LPF), as defined by Criterion A of the Alternative Model for Personality Disorders, and the Hierarchical Taxonomy of Psychopathology (HiTOP) model. However, the integration of LPF within HiTOP remains unclear. Using bivariate correlation and linear regression analyses, this study assessed the associations between LPF and HiTOP spectra (externalizing antisocial, externalizing drug use, internalizing, antagonism, detachment, and psychoticism). A sample of 1,183 participants (46.2% female, Mage = 31.3 ± 14.8 years) from the Italian community completed various self-report measures to capture impairments in personality functioning, and several psychopathology symptoms. Bivariate correlations and regression analyses showed that the LPF facets were consistently associated with all HiTOP domains, even though the LPF measures used in this study appeared more reflective of internalizing symptoms than externalizing ones. The identity facet of LPF was uniquely associated with all outcome criteria, whereas no unique associations were evident for self-direction. Empathy facet had the highest association with antagonism while intimacy presented the highest relation with detachment. Overall, the evidence presented in this study partially supports the construct validity of Criterion A, highlighting its relevance across a wide range of psychopathological symptoms and its potential utility in clinical assessment beyond formal personality disorder diagnoses. Thus, this study may contribute to the understanding of LPF’s role in the dimensional model of psychopathology and underscores the importance of considering personality functioning in the assessment and treatment of mental disorders. 

This time the authors are trying to see how level of personality functioning interacts with psychopathology. I like the fact that they note the bias toward internalizing in the measures they use. The final study looks to the future of HiTOP. Carmichael & Haywood (2025) published “For Clinical Translation, the Hierarchical Taxonomy of Psychopathology (HiTOP) Must Stand on its Own Two Feet” in Journal of Psychopathology and Clinical Science. The edited abstract is as follows:

This article discusses the Hierarchical Taxonomy of Psychopathology (HiTOP). The Hierarchical Taxonomy of Psychopathology (HiTOP) is a large-scale effort involving over 170 researchers to refine the classification of psychopathology. Unlike the Diagnostic and Statistical Manual of Mental Disorders (DSM) and International Classification of Diseases (ICD) diagnostic categories, HiTOP organizes psychopathological symptoms and traits into increasingly broad dimensions based on statistical covariance patterns identified across hundreds of studies, aiming to offer a more scientifically and empirically grounded alternative to conventional nosologies. Since its introduction in 2017, HiTOP has gained significant traction in research, with its foundational publication cited over 3,200 times so far. HiTOP is designed not only as a research tool, however, but also as a framework explicitly intended for clinical application. While HiTOP’s translation into routine clinical practice is still at the relatively early stages, the HiTOP Consortium has made several commendable steps toward this goal with initiatives such as the development of the HiTOP Digital Assessment Tracker, HiTOP Patient Reported Outcome (HiTOP-PRO) measure, a clinical training workshop, ongoing clinical field trials, clinical primers, and resources to support billing when using HiTOP. Overall, the researchers are optimistic about HiTOP’s potential to benefit psychological and psychiatric practice, but we believe its positioning as a clinical tool can be strengthened.

If you’ve stuck with me this far, this is the important article in clarifying that HiTOP is only ultimately helpful if it becomes a clinical tool. We will need to follow its development and the progress being made in other transdiagnostic efforts.