A study in the March edition of the American Journal of Psychiatry empirically challenges the effectiveness of psychiatrists' official diagnostic manual in preventing mistaken, false-positive diagnoses of depression.
The research was done by senior author Jerome C. Wakefield, a professor at the Silver School of Social Work at New York University; Mark Schmitz, of Temple University; and Judith Baer, of Rutgers University. Their findings concerning the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM) criteria for diagnosing depression rebuts recent criticism of earlier research by Wakefield. That earlier research suggested misdiagnoses of depression are widespread and touched off considerable controversy.
According to the DSM, the diagnosis of major depression requires the presence--for two weeks--of at least five out of a list of nine possible symptoms, which include sadness, loss of interest in usual activities, lowered appetite, fatigue and insomnia. However, these symptoms can also occur in normal responses to loss and stress.
False-positive diagnoses occur when someone reacting with intense normal sadness to life's stresses is misdiagnosed as having major depressive disorder. Recent studies suggest a very large percentage of people have such symptoms for two weeks or longer at some point in their lives; therefore, how many of these individuals really are afflicted by a mental disorder or are responding within normal limits to loss or stress has been a matter of debate.
The article, titled "Does the DSM-IV Clinical Significance Criterion for Major Depression Reduce False Positives? Evidence From the National Comorbidity Survey Replication," examines the primary method by which the official diagnostic criteria for depression--the Clinical Significance Criterion (CSC)--are supposed to distinguish normal from disordered cases and thereby prevent false-positive diagnoses. The CSC was added to the symptom and duration criteria in the DSM's fourth edition in 1994 (DSM-IV) in the wake of criticism that too many of the listed symptoms--loss of appetite, say, or sadness, insomnia or fatigue--were being identified as evidence of major depressive disorder even when they were mild and possibly normal responses to distress arising from such events as the loss of a job, the dissolution of a marriage or other triggers for sadness and that such errors might be contributing to the very high reported rates of untreated depression in the American population drawn from epidemiological surveys.
Under the 1994 DSM revision, in addition to the two weeks of sadness and other depressive symptoms, a specified minimal "clinically significant" threshold in the form of harm due to distress or role impairment (in occupational, family or interpersonal contexts) must have resulted from the symptoms in evidence before they could be considered signs of depression. Researchers have subsequently assumed--without definitive evidence--that the CSC eliminates substantial numbers of false positives.
In a 1999 article in the American Journal of Psychiatry, Wakefield and coauthor Robert Spitzer, the originator of the modern DSM symptom-based approach to diagnosis, argued the CSC would not eliminate false-positive diagnoses of major depression because anyone having the specified symptoms, even an individual experiencing a normal intense reaction to loss, would be likely to experience distress or role impairment. Thus, they asserted, the CSC was redundant with the symptom criteria and could not distinguish normal from disordered symptoms, a claim that has come to be known as the "redundancy hypothesis." The researchers' argument was purely conceptual and largely ignored.
The issue of whether the redundancy hypothesis is correct became suddenly more important after Wakefield authored a much-discussed 2007 article in the Archives of General Psychiatry that argued there were indeed large numbers of false-positive diagnoses of major depression in community surveys of mental disorder, possibly as high as 25 to 33 percent. However, that study used data from a national survey conducted before the DSM-IV's addition of the CSC. Therefore, there was no CSC in the criteria that Wakefield and his team used to identify cases of major depression at the time.
Critics of that study argued the lack of a CSC was fatal to the argument because if the CSC had been used, then the supposed false-positive diagnoses Wakefield and his group identified would likely have been eliminated as cases too mild for diagnosis. For example, one noted psychiatrist argued that Wakefield's results were due to a "glitch" in the diagnostic criteria Wakefield used and that the diagnosed individuals identified by Wakefield as having normal reactions would have been eliminated from the depression category if current diagnostic criteria including the CSC were used.
A paper later submitted by Wakefield building on the 2007 article was rejected for publication partly based on a reviewer's assertion that if the CSC had been included in the earlier study, the supposed false positives likely would have been eliminated. So the issue of whether the CSC is in fact redundant or actually eliminated many false-positive major depression diagnoses became key to the still-ongoing debate about the prevalence of depressive disorder.
The latest study, coming in the American Journal of Psychiatry, offers an empirical demonstration, based on nationally representative data, that the CSC fails to distinguish normal from disordered conditions. In this analysis, Wakefield undertook to evaluate independently the impact of the CSC on epidemiological survey estimates of major depressive disorder by using data from a later survey that included a carefully worked-out CSC criterion for depression whose inclusion, according to the claims of its authors, was an effective way of eliminating former false positives. Wakefield then compared estimates of depressive disorder with and without the use of the CSC.
Confirming the redundancy hypothesis put forward a decade earlier, he found the CSC eliminated virtually no one from diagnosis. In fact, even among those people who experienced prolonged sadness without meeting other diagnostic criteria for depression, about 94 percent of them satisfied the CSC just on the basis of the "distress" component alone. Thus the CSC, according to Wakefield and his coauthors, is not doing what it is supposed to do--reducing the overdiagnosis of normal mood fluctuations as depression--and the issue of preventing false positives needs to be revisited.
Contrary to critics' speculations, the earlier findings suggesting many false positives in community surveys cannot be dismissed on the basis of the CSC.
The results take on further importance, Wakefield says, in light of proposals for changes to the DSM in a revision currently taking place that will lead to DSM-V. Concern about increasing false positives is at the heart of criticisms of the proposals put forward by leading psychiatrists, including Allen Frances, the editor of DSM-IV. Moreover, some of the proposals seem to rely heavily on the CSC to justify diagnosis of disorder even when symptoms are minimal when in fact the current research underscores that normal distress can easily satisfy the CSC.