Our interpretation of the results reported here must be tempered by the recognition of several study limitations, including the use of fully-structured lay interviews, the assessment of excessive worry using a single interview question, and the retrospective reporting of lifetime symptoms and course of disorder. These aspects of the study may have reduced our ability to detect reliable differences between excessive and non-excessive subgroups. However, diagnostic classifications of GAD based on the fully-structured interview used here have good individual-level concordance with independent clinician diagnoses based on blinded SCID reappraisal interviews (AUC = .83) and do not differ significantly from clinical diagnoses in estimated prevalence (McNemar χ12
= 1.7, p = .192) (Kessler et al., 2004a
), increasing confidence in the assessment of GAD and, more specifically, in the assessment of excessiveness. It is less clear how the experience of excessive worry may have affected recollections or reports of past anxiety experiences. Additional research will be needed, ideally with a prospective design and more detailed assessment of excessiveness appraisals, to further clarify the relation of excessiveness to the characteristics and correlates of GAD.
With these limitations in mind, we found several differences between excessive and non-excessive worriers who met all other DSM-IV criteria for GAD. Results revealed that excessive worry begins earlier in life, has a more persistent course and greater comorbidity, and is associated with greater symptom severity. At the same time, non-excessive cases have a severity distribution not markedly different from that of excessive cases, significant comorbidity with the vast majority of the other DSM-IV disorders assessed in the survey, and similar odds of parental GAD as excessive cases. In addition, the socio-demographic profile of non-excessive cases is quite similar to that of excessive cases. Finally, non-excessive cases with episodes in the past 12 months reported disability comparable to that of excessive cases. Taken together, these results suggest that non-excessive worry is associated with a somewhat milder symptom presentation than excessive worry but is still sufficiently severe and impairing to warrant a diagnosis of GAD.
The obvious implication of this conclusion is that individuals need not view their worry as excessive to experience clinically significant impairment, at least when worry co-occurs with the other symptoms of GAD. This is consistent with the suggestion in the DSM-IV text that worry can be inferred to be excessive, even if excessiveness is denied by the worrier, so long as other features of pathological worry (uncontrollability, distress, functional impairment) are evident (American Psychiatric Association, 1994
, p. 433). It has been observed that no other DSM disorder, including other disorders involving severe levels of normal emotional processes (e.g., depressed mood in major depressive disorder), requires an explicit judgment of excessiveness as part of its primary diagnostic criteria (Rickels & Rynn, 2001
). The discovery of a group of significantly impaired worriers who are excluded from diagnosis by the excessiveness criterion challenges its appropriateness for GAD as well.
One might ask, given its limited conceptual and evidentiary base, why the excessiveness criterion was originally adopted in DSM-III-R. One reason may have been the desire to avoid pathologizing normative reactions to stressful life events. Because worry is experienced to some degree by most psychologically healthy individuals (Borkovec, 1994
; Muris et al., 1998
), especially in times of stress, the GAD diagnostic criteria must be able to distinguish normal, transient stress reactions from clinically significant anxiety. What is more contentious, however, is how the criteria should classify severe, persistent anxiety that is experienced in response to severe or chronic stressors. Although such anxiety may not be considered excessive, and so would not merit a GAD diagnosis by current DSM criteria, it could still cause considerable suffering and impairment that might benefit from treatment, perhaps especially treatments that focus on enhancing effective coping. For example, Ballenger et al. (2001)
noted that the GAD syndrome is common among patients with chronic physical conditions, but that physicians are often reluctant to diagnose GAD because they consider the presence of anxiety to be normal and justified by the physical illness. Yet this co-occurring GAD often worsens prognosis for the physical illness, which means that failure to detect, diagnose, and treat the GAD could lead to substantially poorer health outcomes for such patients. The considerable symptom severity, psychiatric comorbidity, and functional impairment reported by generally anxious individuals in our sample—even when the anxiety was judged not to be excessive—similarly underscore the potential clinical and public health importance of diagnosing and treating these anxious individuals.
Despite their many similarities, excessive and non-excessive GAD cases were distinguished by several robust differences that remained significant even after worry uncontrollability, distress, and impairment were controlled. These findings raise at least two intriguing questions for future investigation. First, might excessive GAD, with its earlier onset and more chronic, comorbid course, represent a different form of the disorder than non-excessive GAD? It has been suggested that earlier-onset GAD represents a more severe disorder stemming from temperament factors or from extreme early stressors that predispose the individual to a range of emotional disorders, whereas late-onset GAD represents a more circumscribed, less characterological condition precipitated by moderate life stress (Brown et al., 1994
; Campbell et al., 2003
). It is possible that the concepts of excessive GAD and early-onset GAD converge on an overlapping set of individuals who are especially vulnerable to developing severe, chronic emotional disturbance (see Hudson & Rapee, 2004
). At the same time, our finding that excessive GAD is no more familial than non-excessive GAD suggests that the relations among the relevant vulnerability factors may be quite complex. Additional research is needed to determine whether there are distinct variants of GAD for which excessive worry may be a marker.
Second, what leads individuals to describe their worries as excessive? Our finding that excessive GAD is associated with greater symptom severity could indicate that excessive cases actually experience more frequent or intense worry than non-excessive cases. An alternative explanation is that the worry experiences of the two groups are objectively the same, but that the former appraise the experiences in a more negative light than the latter. A growing body of research suggests that severe worriers with and without GAD are distinguished more by their subjective interpretations of worry and anxiety than by the actual frequency, severity, or disruptiveness of their anxiety experiences (Ruscio & Borkovec, 2004
; Ruscio et al., 2003
). There is a need to examine the correspondence of excessiveness appraisals to actual anxiety symptoms, to identify factors other than anxiety symptoms that may lead worry to be appraised as excessive, and to consider the relative weight that should be given to anxiety symptoms versus appraisals of these symptoms when GAD is diagnosed.