Generalized Anxiety Disorder in Patients With Major Depression: Is DSM-IV’s Hierarchy Correct?
Mark Zimmerman and Iwona Chelminski;
Commented by , 30 Mar 2003
Aim of the study
As a rule, DSM-IV allows assignation of multiple diagnoses for presentations that meet criteria for more than one disorder. However, most of the criteria sets include one or more exclusion criteria. In DSM-IV, exclusion criteria are worded in five different ways: “criteria have never been met for …”, “criteria are not met for …”, “does not occur exclusively during the course of …”, “not due to the direct physiological effects of a substance or a general medical condition …” and “not better accounted for by …”.
The DSM-IV criteria set for Generalized Anxiety Disorder (GAD) includes several exclusion criteria. In particular, DSM-IV explicitly requests that the disturbance “does not occur exclusively during a Mood Disorder”. The subject of the present report is the validity of this exclusion criterion and of the hierarchy that it establishes between GAD and Major depression.
Method
The authors evaluated 332 outpatients with major depressive disorder. Subjects were assessed for diagnoses using the Structured Clinical Interview for DSM-IV (SCID), and for severity of symptoms and level of social functioning using questions from the Schedule for Affective Disorders and Schizophrenia (SADS).
In addition, patients completed the 36-item Short-Form Health Survey and the Penn State Worry Questionnaire. Family history was assessed using information provided by the patients.
Patients were divided into three non-overlapping groups: depressed patients with DSM-IV GAD (i.e. meeting all the criteria for DSM-IV GAD including the criterion “does not occur exclusively during a Mood Disorder”), depressed patients with modified DSM-IV GAD (i.e. meeting all the criteria for DSM-IV GAD except for the exclusion criterion “does not occur exclusively during a Mood Disorder”), and depressed patients without GAD.
The authors compared the demographic, psychosocial, family history, and clinical characteristics of the three groups, using one-way analyses of variance and pairwise comparisons.
Results
The depressed patients with DSM-IV GAD and the depressed patients with modified DSM-IV GAD did not differ from each in their demographic, clinical, psychosocial, an family history. On the other hand, both groups differed on these variables from the group of depressed patients without GAD.
Discussion
The findings of the present study question the validity of the DSM-IV exclusion criterion for GAD “does not occur exclusively during a Mood disorder”. As a consequence, the authors suggest that this criterion be eliminated from the criteria set for GAD i.e. that GAD should be diagnosed whether or not the anxiety symptoms are limited to the depressive episode.
The study may have treatment as well as prognostic implications for Major Depression. The major point of interest of the investigation lies, however, in the fact that it highlights one of the main difficulties inherent in a classification that includes specified exclusion criteria among its criteria sets.
There are many such criteria in DSM-IV and the validity of most of these criteria have as yet not been investigated in empirical studies. The study by Zimmerman and Chelminski provides a good example of how this can be done.