What Is the DSM, And Why Do We Need It?

June 12, 2013

DSMI recently attended the 166th annual meeting of the American Psychiatric Association (APA) in San Francisco.  The 5th version of the Diagnostic and Statistical Manual (DSM), the DSM-5, was officially released at this meeting.  Earlier versions of the DSM were introduced in 2000 (DSM-4), 1980 (DSM-3), 1968 (DSM-2), and 1952 (DSM-1).

In general, clinical psychiatrists are happy with the improvements provided by successive DSMs.  However, there are criticisms from various sources, including the National Institute of Mental Health (NIMH) and some therapists, who point out that the conditions included in the DSM-5 (and earlier DSM versions) are not biologically based like diagnoses in other branches of medicine.  This is certainly true.  Nearly all DSM conditions are “syndromes”, i.e., clusters of symptoms, rather than actual biological diseases like diabetes mellitus, hypertension, or hypothyroidism.  Two possible exceptions are Alzheimer’s Disorder and narcolepsy, both in DSM-5, which are associated with biological (gene or neurohormone) abnormalities.

The issue was recently discussed in detail on National Public Radio’s Science Friday program, hosted by Ira Flatow.  Panelists included Jeffrey Lieberman (APA president), Thomas Insel (NIMH director), and Gary Greenberg (therapist and author of The Book of Woe: the DSM and the Unmaking of Psychiatry).  There were also useful comments from two callers (Dave and Joe).  The audio tape and written transcript of the radio show are available here.

The program was useful and informative.  The three panelists did not disagree significantly with each other, but presented different aspects of the DSM-5’s potential impact on our society.  I encourage blog readers who wish to hear more about this issue to listen to the tape or read the text.  In the present blog I provide my comments as if I were a fourth panelist.  As therapist, prescriber of psychotropic medications, and former neuroscience researcher, I appreciate the perspectives of the three panelists.

An important issue in the DSM-5 debate involves the mind-body dichotomy, which dates back to Descartes (1596 – 1650).  If the mind resides in the brain, which many of us in psychiatry and neuroscience believe, there is no mind-body dichotomy, and psychiatry will one day be folded into medicine, along with neurology.  Just as the brain has centers that control the muscles, nerves, and organs of the body (in the domain of neurology), it also has centers responsible for emotion, feeling, thinking, and decision-making (in the domain of psychiatry).  With time, a DSM-10 or 15 will specify mental illnesses in relation to particular brain centers.  This would seem to be the view of Drs. Lieberman and Insel, though perhaps not of Mr. Greenberg, on the radio show.

According to such principles, current psychotropic medications are too nonspecific in relation to brain localization, but address particular neurotransmitters such as serotonin (e.g., fluoxetine), norepinephrine (e.g., bupropion), dopamine (e.g., risperidone, dexedrine), or benzodiazepines (e.g., clonazepam) at many brain locations.  Future drugs may address particular brain sites for a given transmitter or particular locations on the genome.  It is in the best interest of everyone, not just drug companies, for such future drugs to be developed.

The American DSM, which covers psychiatric disorders, and the International Classification of Disease (ICD), which covers medical disorders (including psychiatric disorders), are companion systems, with the ICD providing only the names of medical diseases/disorders, and the DSM providing sets of symptoms that comprise each psychiatric disorder.  Most likely, as Dr. Lieberman points out, current psychiatric disorders like schizophrenia, will in future be broken down into a series of separate disorders, as has occurred with medical diseases like breast cancer.  Each form of schizophrenia might turn out to have its own unique set of brain locations.

The DSM does not specify treatment.  Medical treatment in general, including psychiatric treatment, is currently supposed to be “evidence-based”: i.e., scientifically proven using “double blind” procedures, in which neither doctors nor patients know whether an actual treatment or a “placebo” is being used, and with statistical validation of results in relation to probability principles.

Many insurance companies require treatment to be evidence-based in order to be reimbursed.  DSM diagnoses provide the basis for conducting evidence-based studies using only patients that fit into a particular diagnostic category.  All new drugs appearing on the market in the US require evidence-based studies showing efficacy and safety before the US Food and Drug Administration (FDA) will approve them for use by the general public.

With better diagnoses, better medications, and the use of evidence-based treatments for particular psychiatric disorders/diseases, it is hoped that the cost of treating psychiatric illness will be manageable.  Contrary to popular mythology, the number of separate diagnoses in the DSM-5 is less, rather than more, than in the DSM-4.

Most pathologic conditions exist in a continuum with the “normal” range (there being no unique normal).  This is true of both psychiatric disorders and medical diseases.  As our understanding of psychiatric illness improves, we will be better able to define the normal range, as is now possible with such medical entities as blood pressure, blood sugar, thyroid hormone levels, and body weight.

The bottom line is that the DSM-5, whatever its limitations, is the best manual we have in 2013.  Not a Bible at all, but a work in progress, it is expected to change every few decades, improving at each step, until eventually it becomes a list of biologically based psychiatric diseases rather than disorders.  Some psychiatric conditions may turn out to be time-limited illnesses or injuries (like pneumonia, dehydration, or contusion); others may turn out to be chronic, like arthritis, atherosclerosis, or hypothyroidism.