The Multi-Dimensional Structure of Psychotic Disorders

IntroductionTraditional classification systems based on broad nosological categories do not adequately capture the high heterogeneity of mental illness. One possible solution to this is to move to a multi-dimensional model of mental illness, as has been proposed by the Research Domain Criteria and Hierarchical Taxonomy of Psychopathology frameworks. In this study, we explored the dimensional structure of psychotic disorders. To our knowledge, this is the first study to investigate this in a sample of early psychosis and chronic schizophrenia patients.MethodsWe used exploratory factor analysis to identify the central dimensions in the Lausanne Psychosis data, a multi-modal prospective data set that includes a broad behavioral assessment of patients diagnosed with psychotic disorders. We evaluated the validity of these dimensions by regressing them to several clinical and functional outcome measures as well as substance use.ResultsOur analysis revealed four behavioral dimensions: Cognition, Internalizing, Thought Disorder, and Detachment. They were related to functioning, but unrelated to substance use, both measured at the same point in time.ConclusionsThis study advances the development of a multi-dimensional characterization of psychotic disorders, and suggests that a multi-dimensional structure can be an additional method to capture psychopathology with predictive validity in people with psychosis. The study highlights the importance of cognition and internalizing dimensions in patients with psychosis.