The US-based National Institute for Mental Health (NIMH) is to move its research focus away from DSM (Diagnostic and Statistical Manual of Mental Disorders) categories and towards research projects that look across current categories, its director has revealed.

Thomas Insel revealed the move in a blog on the organisation’s website. The move comes only a few weeks ahead of the publication by the American Psychiatric Association of the new fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), the sector’s ‘Bible’, which aims to provide a common language for describing psychopathology.

Insel said that while the strength of the DSM is that it ensures that clinicians use the same terms in the same ways, the weakness is its lack of validity. “Unlike our definitions of ischemic heart disease, lymphoma, or AIDS, the DSM diagnoses are based on a consensus about clusters of clinical symptoms, not any objective laboratory measure,” he wrote. “In the rest of medicine, this would be equivalent to creating diagnostic systems based on the nature of chest pain or the quality of fever.”

Research Domain Criteria project

As a result, the NIMH has launched the Research Domain Criteria (RDoC) project. The aim of this decade-long project is to transform diagnosis by incorporating genetics, imaging, cognitive science and other levels of information to lay the foundation for a new classification system.

Insel wrote that the approach began with several assumptions:

• A diagnostic approach based on the biology as well as the symptoms must not be constrained by current DSM categories
• Mental disorders are biological disorders involving brain circuits that implicate specific domains of cognition, emotion, or behaviour
• Each level of analysis needs to be understood across a dimension of function
• Mapping the cognitive, circuit, and genetic aspects of mental disorders will yield new and better targets for treatment.

The RDoC is designed to be a framework for collecting data for a new classification system, which will be based on emerging research data, rather than current symptom-based categories used in the DSM.

“We need to begin collecting the genetic, imaging, physiologic, and cognitive data to see how all the data – not just the symptoms – cluster and how these clusters relate to treatment response,” Insel wrote.

Insel claimed that a new system would benefit patients because it would lead to a more precise diagnostic system.

“RDoC is nothing less than a plan to transform clinical practice by bringing a new generation of research to inform how we diagnose and treat mental disorders,” he concluded.

The major RDoC research domains are:

• Negative Valence Systems
• Positive Valence Systems
• Cognitive Systems
• Systems for Social Processes
• Arousal/Modulatory Systems.