In a prior blog, Grief/Major Depression, I commented in the final few sentences that ultimately research would draw the dividing line between normal grief and major depressive disorder. When I wrote that, I was thinking about the ideas that follow. Research Domain Criteria (RDoC) is an initiative by National Institute of Mental Health (NIMH) to try to begin bridging the gap between the new findings of neuroscience and the self-reported, symptom clusters that are currently used to define psychiatric syndromes. Symptoms not causes. Symptom complexes are not specific enough for research purposes and thus for finely tailored treatment recommendations which are applied daily to millions of individuals. A good example to clarify this problem is to be found in the aforementioned major depressive disorder. To meet criteria currently, one needs five of nine symptoms. You could have two patients who have the same diagnosis and share only one symptom. It is highly unlikely that they would share the same genetic, molecular, circuit and even behavior but would be in the same diagnostic group for research or treatment purposes. The fact that this Diagnostic and Statistical Manual of Mental Disorders, fourth edition, (DSM-IV) grouping is used by insurance for claim processing, the Food and Drug Administration (FDA) for drug trials, International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD-10), as a factor in legal proceedings and many other institutional and classification projects makes it now a major impediment because these classifications do not map onto the genetic and neuroscience findings as they are quickly emerging at this time. These DSM diagnoses are heterogeneous, involve multiple brain regions and are, therefore, not suitable for research purposes.
The RDoC is an attempt to start the process of identifying the neural circuits that produce a symptom or disorder and ultimately to produce a diagnostic classification that is based on neuroscience. This is then first and foremost a guide for researchers to classify patients for their studies. There is no intention to try to replace DSM-V any time soon. A detailed and clear presentation can be found at the link above.
The following chart which I have copied from the NIMH site nicely summarizes the type of analysis that is being attempted. RDoC embodies three principles: 1, it is dimensional - normal to abnormal range, and levels of effects - genes cells, molecules, circuits, and behavioral observations; 2. there is no attempt to correlate with current DSM diagnostic categories; 3. all levels of analysis will be used including physiological, behavior, imaging, and self-reporting to choose a unit of analysis that is called a construct and is represented by the entries in rows on the chart. The drafters anticipate that most research investigations in the future will focus on the constructs.
|DRAFT RESEARCH DOMAIN CRITERIA MATRIX|
|– – – – – – – – – – –||UNITS OF ANALYSIS||– – – – – – – – – – –|
|Cognitive (effortful) control|
|Imitation, theory of mind|
|Facial expression identification|
|Arousal & regulation (multiple)|
|Resting state activity|
While it is true that this proposal does not take into account developmental issues or interpersonal or environmental impact, I believe this is a tremendous leap forward and should be supported by all. I encourage all readers to click on the RDoC link at the beginning of this blog for a more complete description and discussion of the project and especially of the Constructs.