Psychiatric Diagnosis: Where's the Science?

Nassir Ghaemi, MD, MPH

Disclosures

May 19, 2011

In This Article

NIMH RDoC vs DSM: Introduction

The recent National Institute of Mental Health (NIMH) Research Domain Criteria (RDoC) proposal has not received as much attention as the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) draft proposal, but the 2 ideas are linked. NIMH leadership has concluded, as some suggested in 1980 with the DSM-III, that we need 2 sets of diagnostic criteria: one for practice (DSM-5) and one for research (RDoc). The one for practice can be based on "pragmatic" decisions about diagnostic criteria; the one for research should be "real." Now what does this mean?

The pragmatic DSM-5 is not primarily a scientific document: Criteria are chosen by psychiatric leaders in the task force committees, and in the oversight of the overall DSM leadership, on the basis of what they think is best for psychiatric practice. These considerations can be scientific, eg, if there is a consensus on evidence for certain diagnostic definitions on the basis of research studies. Inevitably, other considerations also apply. A primary use of the DSM document is for insurance reimbursement; it is used to check off boxes to tell insurance companies why a patient is receiving psychiatric care. However, there are other uses: Lawyers often will use DSM diagnoses in lawsuits, such as in malpractice cases, to establish a "standard-of-care" definition of what diagnoses can be legitimately identified in clinical practice. Professors use DSM to teach undergraduate and graduate classes in psychology; social work schools and psychiatry residencies also use DSM, of course, as a central text for teaching psychopathology and nosology. The federal government uses it when the National Institutes of Health (NIH) grant committees decide which grants will get taxpayer funds, and which won't; DSM criteria almost always need to be followed. The US Food and Drug Administration (FDA) uses it when deciding which drugs can be allowed to enter the market; almost always, DSM criteria are used to establish uses of drugs.

Consequently, the pharmaceutical industry, which follows FDA guidelines, tends to conduct studies mainly with DSM-defined methods. Because pharmaceutical industry funding is the source for most clinical research, DSM definitions are the basis for much of the clinical knowledge that is provided to the average clinician who reads scientific journals. Journal reviewers tend to prefer DSM diagnoses and are wary of allowing publication of articles with other diagnostic approaches; therefore, DSM definitions constrain most of the science that is conducted on the biology and psychopathology and treatment of mental illnesses.

It is hard to overstate the influence of DSM definitions; the term "Bible of psychiatry" is not a random metaphor.

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