For several years, a workgroup at the National Institute of Mental Health (NIMH) in Bethesda, Md., has been designing a framework for creating a new way to classify mental disorders; one built on decades of neuroscience-based research that is changing researchers’ understanding of how the brain produces adaptive behavior and how a patient’s functionality turns from normal to abnormal in forms of various mental disorders.
Research Domain Criteria – or RDoC – would be a new organizational framework that would help researchers better listen to what the brain can tell them about classifying certain mental disorders rather than simply looking at behavioral symptoms and signs.
“We hope RDoC will serve as a useful research tool to push the status quo, and to help look at diagnosing mental disorders from a different perspective,” says Sarah Morris, Ph.D., program officer for the Schizophrenia Spectrum Disorders Research Program in the NIMH’s Division of Adult Translational Research and member of the RDoC workgroup.
The Research Domain Criteria Project operates on the premise that for many years, says Morris, mental illness diagnoses have been based on whether patients’ symptoms fall into the particular diagnostic categories outlined in the Diagnostic and Statistical Manual. However, when patients’ symptoms overlap several categories or don’t meet full criteria for a diagnosis, it can make them harder to classify. When this happens, “potential participants are excluded from research or grouped into very heterogeneous categories” because of where their diagnosis does or doesn’t fit in.
“Important information about patients with co-occurring disorders or ‘NOS’ diagnoses that put them between categories is getting lost,” says Morris. “[RDoC] encourages researchers to think in much more dimensional and interdisciplinary ways.”
According to the NIMH, Research Domain Criteria is guided by three principles, all of which split from diagnostic approaches being used today.
First, Research Domain Criteria is conceived as a “dimensional system,” reflecting things like circuit-level measurements and behavioral activity that ranges from normal to abnormal. These multiple dimensions would include behavior and thought patterns, along with neurobiological measures and genetics.
Second, it is intended to create classifications from basic behavioral neuroscience, so rather than starting with an illness definition and looking for its brain-based underpinnings, RDoC starts with the current behavior-brain relationship and then links to the clinical phenomena.
Finally, it will use different units of analysis (e.g., imaging, physiological activity, behavior and self-reported symptoms) to define constructs, which are specific functional dimensions of behavior that, with advances in science, are subject to continual refinement.
According to Morris, NIMH Director Thomas Insel, M.D., and Bruce Cuthbert, Ph.D., director of NIMH’s Division of Adult Translational, have been among those instrumental in launching the Research Domain Criteria initiative.
As for additional Research Domain Criteria support, Morris says, “We have had terrific support from many, many scientists who have helped to shape the RDoC framework by attending the workshops, responding to surveys and serving on the RDoC workgroup.”
Research Domain Criteria is in the early stages of development. Morris says it is important that it is not considered to be a replacement to the DSM. “RDoC and the DSM serve two different functions. RDoC is a classification system for research purposes that is grounded in brain-based research.” As for its application and relevance for licensed psychologists, Morris says “time will tell” how they will be affected by the Criteria, but she is hopeful that it will help advance pharmacological and psychosocial treatment.
By Jennifer E Chase