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Psychiatry

The Most Important Controversy in Current Psychiatry

Dimensional Diagnosis versus Categorical Diagnosis

© Nevit Dilmen, Wikimedia Commons
Source: © Nevit Dilmen, Wikimedia Commons

In January, 2010, NIMH announced the development of a new schema for the classification of psychiatric illness: RDoC, or Research Domain Criteria http://www.nimh.nih.gov/news/science-news/2010/genes-and-circuitry-not-…. This system was intended to be a research and diagnostic tool; it reflected dissatisfaction with the value of the DSM system in clinical research. According to NIMH, the clinical categories of DSM had little correspondence with genetic or neurological measures. DSM had led psychiatric research into a blind alley according to RDoC’s advocates. For the field to progress, a new system of classifying psychiatric phenomena needed to be developed. RDoC relies on dimensions; the DSM relies on disease categories, e.g., Depression, Schizophrenia. To oversimplify greatly, RDoC might explore anger by mapping out what is known about the genetics of anger, the neural circuits that transmit anger impulses, the neural structures involved in anger, and cognitions related to anger on a matrix or grid. In RDoC there would be no attempt to organize anger by specific disease category. RDoC is a system for the study of biological psychiatry. (RDoC has been treated previously in this blog at https://www.psychologytoday.com/blog/your-child-does-not-have-bipolar-d…. Also see RDoC at the NIMH website devoted to RDoC hot-linked above and later in this post).

Although RDoC had been developed and was known to psychiatric researchers for several years before the rollout of DSM-5, several days before the rollout date of DSM-5, Thomas Insel, the Director of NIMH, gave a public scathing critique of the DSM system, which served to further undermine the creditability of DSM-5 http://www.nimh.nih.gov/about/director/2013/transforming-diagnosis.shtml. The NIMH RDoC group and the American Psychiatric Association quickly managed to paper over their differences and present something of a united front on the brink of the launch of DSM- 5. NIMH has continued to advocate for the RDoC approach to understanding psychiatric phenomena.

The distinguished psychiatric research journal, JAMA Psychiatry, in the December, 2015, issue, published a debate between advocates of the RDoC approach to psychiatric research and classification versus the categorical or DSM approach to psychiatric research and classification (1). Because critiques of DSM are well known, and critiques of RDoC are much less well known, this post will focus on the critique of RDoC in the published debate of JAMA Psychiatry.

The critique had two central tenets: (1) a dimensional approach does not permit the discrimination between health and illness, and (2) there is no scientific or evidence base for the RDoC approach to psychiatric research.

First, the failure of RDoC to provide a means to discriminate between health and illness is based on its reliance on dimensions as critical measures. To have more or less of some biological quality does not distinguish between who is well and who is ill. As pointed out, a patient who is short may simply be at one end of the spectrum for height or may have one of several diseases that manifest in short stature. Examining height alone will not make that determination. Thus it was argued the crucial ingredients for psychiatric diagnosis cannot be found in the continuous measures of symptom dimensions or continuous biological mechanisms. There is a discontinuity between healthy individuals and psychiatrically disturbed individuals. Further, it was argued, many psychiatric medications do not work on healthy people but have significant influence on psychiatrically disturbed persons. There[S1] may be continuities in some biological or psychological measures between the well and the ill, but the continuous variables cannot explain the difference between well and ill individuals. Other extrinsic information, such as impairment in the ability to function must be considered to make a diagnosis or reject one.

Second, according to the RDoC critique, there is no scientific or evidence base for the RDoC initiative. The core working document for RDOC is the matrix. The matrix is a grid with the following eight topic heads at the top of the columns: genes, molecules, cells, circuits physiology, behavior, self reports, and paradigms, crossed by threats, rewards, memory, perception, and a large number of other constructs. The genes, molecules, and circuits associated with these constructs are identified and studied. Diagnosis is not one of the constructs. In the debate, the critics of RDoC claim there is no scientific evidence for these various categories and dimensions. The categories seem reasonable, the critics state, but the categories are merely guesses about what might work. The categories were developed largely by researchers with no clinical experience, according to the critics. There is no evidence to support the RDoC catagories’ utility in developing data that will help treat people in distress or effectively decide who is well or who is sick.

NIMH has resolved to fund research that uses RDoC format rather than DSM format. This control of research funding will be decisive in the outcome of the argument. There is no reason to place all of the eggs of U.S. psychiatric research monies in the basket of RDoC. RDoC deserves limited funding to develop an empirical basis for its dimensions and potential relationship with diagnostic categories. Research funds not used for RDoC should be put to other worthwhile research studies.

1.Weinberger, D. Glick,and Klein DF, Whither Research Domain Criteria (RDoC)? The good, the bad and the ugly. JAMA Psychiatry 12:2015, 72:pp 1161-1162ee pages 1159, 1163 and 1165 for additional commentary in the same issue of the journal

Copyright: Stuart L. Kaplan, M.D., 2016.

Stuart L. Kaplan, M.D., is the author of Your Child Does Not Have Bipolar Disorder: How Bad Science and Good Public Relations Created the Diagnosis. Available at Amazon.com.

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