Restoring Course as a Core Diagnostic Element of Psychotic Disorders

Foundational models of the psychoses included course as a core element differentiating patients. Current models, ICD-11 and DSM-5, only require symptom criteria to be met to make a diagnosis. We explore the proposition that making course designation essential, again, would improve the categorization of patients with psychotic disorders.

We briefly discuss the history by which symptoms, alone, became the primary elements required for diagnosis. We review past and recent evidence on the best models for differentiating among psychoses.

The use of course designations, along with symptoms, produces the best fit to the way in which psychotic disorders present and progress. It also matches how clinicians assess patients and choose therapeutic interventions. A model including course as a factor is more accurate and complete than models using symptoms alone. And it produces groups of patients that are likely to be more homogeneous than purely symptom-based models. The degree of heterogeneity among patients classified together within current International Classification of Diseases (ICD) and Diagnostic and Statistical Manual of Mental Disorders (DSM) categories can lead to false findings in research and a lack of clarity on the best treatment in individual cases. Increasing homogeneity in diagnostic groups, by including course designations, could advantage clinical care, clinical trials, and research on underlying pathogenic mechanisms.

Adding a course as a diagnostic element is practical. Clinicians already consider it. Specifying courses can be required in making a diagnosis. Doing so is evidence based and enhances the accuracy and value of diagnoses. We recommend restoring the course as a core element of any new diagnostic system.