Progress in achieving quantitative classification of psychopathology

Abstract

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.

Psychiatric Comorbidity as a Function of Severity: DSM‐5 Alcohol Use Disorder and HiTOP Classification of Mental Disorders

“…The established limitations of categorical classifications of psychiatric disorders (e.g., heterogeneity within diagnostic categories, lack of coverage, arbitrary cutoffs, diagnostic co‐occurrence; Krueger et al, ; Trull and Durrett, ) have contributed to the development of dimensionally oriented diagnostic classification systems. Dimensional approaches have a strong empirical basis (Krueger et al, ) and are increasingly incorporated into diagnostic systems. For instance, DSM‐5 (American Psychiatric Association, ) has initiated a transition toward dimensional approaches (e.g., autism spectrum disorder, AUD, SUDs), and the International Classification of Disease, Eleventh Revision (World Health Organization, ) has incorporated dimensional aspects of classification, such as including severity ratings within disorders (e.g., PDs) and grouping disorders based on common factors (e.g., multiple anxiety disorders clustered together given their commonality of a “fear” component; Reed et al, ).…”

Delineating and validating higher-order dimensions of psychopathology in the Adolescent Brain Cognitive Development (ABCD) study

“…Traditional psychiatric nosologies define mental disorders as distinct categories, 1, 2 but this is at odds with extensive evidence that disorders lie on a continuum with normality and are highly comorbid. 3–7 This comorbidity reflects underlying higher-order dimensions (or spectra) of psychopathology. 4, 7–9 Dimensional classifications of these spectra have been proposed as alternative approaches to better align the nosology with empirical evidence.…”

“…3–7 This comorbidity reflects underlying higher-order dimensions (or spectra) of psychopathology. 4, 7–9 Dimensional classifications of these spectra have been proposed as alternative approaches to better align the nosology with empirical evidence. 4, 7, 8, 10 However, available models differ in the number of spectra that they specify.…”

“…19, 20 However, further evidence suggests that a greater number of major dimensions are needed to characterize psychopathology. 8, 21–25 For instance, the recently-developed Hierarchical Taxonomy of Psychopathology (HiTOP) 7, 8 includes six spectra (internalizing, somatoform, detachment, thought disorder, antagonism, and disinhibition), which were identified based on extensive factor analytic literature (for a review see 8 ). Yet, the dimensions depicted in these studies may not provide full coverage of psychopathology.…”

Conceptual work to advance psychiatric and neuroscientific sophistication: a report by the WPA Section on Philosophy and Humanities in Psychiatry

“…A recent Forum in World Psychiatry , with an introductory paper and a set of commentaries, is a fine example of how empirical and conceptual work come together in diagnostic classification of psychopathology. From both clinical and philosophical backgrounds, the authors of the introductory paper represent a consortium working towards a Hierarchical Taxonomy of Psychopathology (HiTOP).…”