Reconceptualizing schizophrenia in the Hierarchical Taxonomy Of Psychopathology (HiTOP)

Abstract

The concept of schizophrenia, operationalized in diagnostic manuals, faces existential challenges of low reliability, arbitrary boundaries, overlap with other disorders, and heterogeneity. The Hierarchical Taxonomy Of Psychopathology (HiTOP) was developed to address these challenges. It conceptualizes psychotic disorders as continuous with normality. To alleviate heterogeneity, psychotic disorders are decomposed into 14 tightly-knit symptom and trait dimensions. These narrow dimensions form two broader spectra-psychoticism (e.g., positive symptoms, peculiarity, fantasy-proneness) and detachment (e.g., negative symptoms, emotional detachment, romantic disinterest)-that comprise the psychosis superspectrum. The full HiTOP model includes four other spectra that can be useful in a comprehensive evaluation. This model is undergoing rigorous validation. It has shown greater reliability, explanatory power, and prognostic value than schizophrenia diagnosis. The HiTOP approach produced promising evidence of clinical utility in surveys of clinicians. The HiTOP reconceptualization of schizophrenia suggests four major implications. First, schizophrenia spans two spectra, and therefore detachment is important to study including in people who have never been psychotic. Second, large population-based studies with comprehensive profiling of psychopathology can address shortcomings of case-control design. Third, elevations on psychoticism and detachment dimensions early in life offer opportunities for prevention. Fourth, actionable ranges can be identified on dimensions to guide specific clinical decisions. The elaborate HiTOP model may be unnecessary in acute treatment settings, but it can benefit prevention, long-term management, and research. The categorical schizophrenia concept offers valuable continuity and can be used in parallel with HiTOP, but we predict that eventually the dimensional approach will make this category obsolete.