By Ferris Jabr*

Part 2 of a series

In the offices of psychiatrists and psychologists across the country you can find a rather hefty tome called the Diagnostic and Statistical Manual for Mental Disorders (DSM).

The current edition of the DSM, the DSM-IV, is something like a field guide to mental disorders: the book pairs each illness with a checklist of symptoms, just as a naturalist's guide describes the distinctive physical features of different birds. These lists of symptoms, known as diagnostic criteria, help psychiatrists choose a disorder that most closely matches what they observe in their patients. Every few decades, the American Psychiatric Association (APA) revises the diagnostic criteria and publishes a brand new version of the DSM. The idea is to make the criteria more accurate, drawing on what psychologists and psychiatrists have learned about mental illness since the manual's last update.

In May 2013, the APA plans to publish the fifth and newest edition of the DSM, which it has been preparing for more than 11 years. On its DSM-5 Development website, the APA states that the motivation for the ongoing revisions was an agreement to "expand the scientific basis for psychiatric diagnosis and classification." The website further states that "over the past two decades, there has been a wealth of new information in neurology, genetics and the behavioral sciences that dramatically expands our understanding of mental illness."

In other words, the APA intended to make the DSM-5 the most scientific edition of its reference guide yet, which would be a real boon for a book that has been routinely lambasted as fiction borne out of convenience, rather than a solid clinical text grounded in research. Now, only one year away from the planned publication of the DSM-5, most psychiatrists have accepted that the APA's initial optimism about informing revisions with cutting edge science is well intentioned, but premature. Most of the proposed revisions to current DSM criteria—many of which are genuine improvements—are based not on insights from genetics and neuroscience, but rather on clinical experience, prevalence studies and plain old common sense. Indeed, many of these changes could have been made years ago. (For more on these changes, see "Psychiatry's 'Bible' Gets an Overhaul," by Ferris Jabr, Scientific American Mind, May/June 2012.)

Cutting and Collapsing Categories

Consider, for example, that the DSM-IV organizes schizophrenia into six types, all of which the APA proposes eliminating from the DSM-5. Why? Because these archaic subcategories were never grounded in empirical research in the first place; they were just what sounded good to the DSM authors of yore. In truth, these ostensible types of schizophrenia probably do not exist. Similarly, the APA is nixing three of the 10 current personality disorders, essentially acknowledging that these were never legitimate illnesses in the first place. So many people fit the criteria for more than one personality disorder simultaneously that 10 varieties become superfluous.

Likewise, the DSM-5 collapses four of the five current pervasive developmental disorders—including autistic disorder and Asperger's—into a single category called autism spectrum disorders, because there is so much overlap in their respective criteria. None of these revisions are founded on recent revelations from genetics and neuroimaging research. Study after study has failed to discover a set of genes or unusual brain structures that reliably identifies major mental disorders. Rather, these are changes that many psychiatrists have been advocating for the past two decades based on their everyday clinical experience, studies of illness prevalence and the sense that some of the current criteria do not make sense. Despite awareness of these flaws, the APA did not get around to updating the DSM until now, the first substantial revision in 30 years.

One exception to the APA's disappointed ambitions to base the ongoing revisions on neuroscience are the proposed changes to addictions. Scientists understand quite a bit about how the addicted brain differs from a typical brain. The APA has proposed adding gambling disorder to the DSM-5, in part because reward circuits in the brains of gambling addicts light up in the same way as those in alcoholics and drug addicts. Still, some researchers worry that the DSM will end up sanctioning addictions to everything—gambling, sex, the Internet—shifting focus to what people are addicted to from why addictions form in the first place.

Flaws in the Process

All the proposed revisions to the DSM-5 emerge from the task force: 27 scientists affiliated with the APA who sort through all the relevant research literature. In the past, many psychiatrists have criticized the APA for not creating an independent review committee to examine this literature—a group of scientists who are not obligated to appease the APA.

In January of this year, David Elkins, president of the Society for Humanistic Psychology, authored an open letter to the APA calling for such independent review: "As you know, it is common practice for scientists and scholars to submit their work to others for independent review…Will you submit the controversial proposals in DSM-5 to an independent group of scientists and scholars with no ties to the DSM-5 Task Force or the American Psychiatric Association for an independent, external review?" [Emphasis theirs]

In a letter of its own, the APA responded: "There is, in fact, no outside organization that has the capacity to replicate the range of expertise that DSM-5 has assembled over the past decade to review diagnostic criteria."

Recently, the APA has mentioned here and there that it has in fact created such a "scientific review committee," separate from the task force, but you will not find any satisfactory description of it or its responsibilities on the DSM-5 Development website. Darrel Regier, vice-chair of the Task Force, explained that the committee includes about six scientists selected by the board of trustees, because "there is no way you can have truly independent review," and declined to say more. Allen Frances, chair of the DSM-IV Task Force and the most outspoken critic of the DSM-5, says that the APA only created this group at the last minute in response to criticisms. "The scientific review committee is not even transparent," Frances says. "They report confidentially to APA."

Frances and other critics have pointed to a related flaw in the ongoing revisions. Every time the APA revises the DSM, it conducts "field trials" of new diagnostic criteria. These are dry runs of the proposed revisions in clinical settings that test their reliability—that is, whether two different psychiatrists using the new criteria reach the same conclusion about a given patient.

Since 2010, the APA has been conducting field trials for the proposed DSM-5 diagnostic criteria. (For more on the results of the field trials, click here.) Critics contend—and Regier confirms—that the trials fail to explicitly compare the criteria suggested for the DSM-5 to that in the DSM-IV, except in the case of post-traumatic stress disorder. That is like a taste test in which the judges decide that a new diet soda is better than its non-diet predecessor because everyone approved of the flavor, even though the judges never bothered to directly compare the diet and regular versions. Although in past revisions the APA has done such a comparison, Regier says that this time doing so would double the size of the survey, making it too costly and time-consuming to conduct. "You just don’t do science that way," Frances says.

*Ferris Jabr is an Associate Editor at Scientific American

Tomorrow: Edward Shorter, a historian of psychiatry at the University of Toronto, argues that the principal diagnoses of the DSM—depression, schizophrenia and bipolar disorder—are artifacts and should essentially be discarded.