ICD and DSM, the standard manuals for psychiatric diagnosis, have each recently been revised. These newest versions have modest updates and retain primarily categorical models. There is growing evidence that these primarily categorical structures of both ICD and DSM do not fit either the clinical presentations of patients, recent discoveries from genetics and neurobiology, nor therapeutic choices well. This commentary reviews the state of current evidence on the structure of psychiatric disorders, focusing on psychotic and mood disorders. That review suggests that future revisions should consider the widely replicated findings that patients present with an individual combination of symptoms or factors, each of specific severity, and that it is these symptoms and factors and their severity that clinicians identify and treat. Moving to such a system loses no details from the current models and adds crucial information on personal aspects of illness and the dimensionality of their conditions. The result would be updated versions of ICD and DSM with improved validity and utility. And such a model would be practical, because clinicians already use it in their work.
