اعتبار بیشتر از یک مدل شناختی-رفتاری اختلال اضطراب فراگیر: ویژگی های تشخیصی و علائم

The goal of this study was to investigate the diagnostic and symptom specificity of a model of GAD that has four main features: intolerance of uncertainty, positive beliefs about worry, poor problem orientation, and cognitive avoidance. The authors compared 17 patients with non-comorbid generalized anxiety disorder (GAD) to 28 patients with non-comorbid panic disorder with agoraphobia (PDA) and found that only intolerance of uncertainty showed evidence of diagnostic specificity, i.e., intolerance of uncertainty scores were higher in the GAD group relative to the PDA group. In terms of symptom specificity, when both groups were combined, all model variables were significantly related to worry but unrelated to fear of bodily sensations, agoraphobic cognitions, and behavioral avoidance. Taken together, these findings provide further support for the link between intolerance of uncertainty and GAD and underscore the importance of pursuing the issue of specificity from both a diagnostic and symptom perspective.

The diagnosis of generalized anxiety disorder (GAD) was initially introduced in the third edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-III, American Psychiatric Association, 1980). At that time, GAD was considered a residual diagnostic category that was defined by a protracted series of symptoms of anxiety, most of which were non-specific. Later revisions of DSM (DSM-III-R, American Psychiatric Association, 1987; DSM-IV, American Psychiatric Association, 1994) have emphasized the role of worry in GAD, and have attempted to identify somatic symptoms that do not overlap with those of other mood and anxiety disorders. Despite the significant progress made since DSM-III, identification of GAD-specific somatic symptoms has remained a challenge (Joormann & Stöber, 1999), and only one of the six GAD somatic symptoms (i.e., muscle tension) is not listed in the diagnostic criteria of at least one other mood or anxiety disorder (DSM-IV, American Psychiatric Association, 1994). This turn of events has led many experts in the area of anxiety to consider excessive and uncontrollable worry about a number of events or activities to be the cardinal feature of GAD (Borkovec & Newman, 1999; Roemer, Orsillo, & Barlow, 2002; Wells, 1999). As research has led to more parsimonious and specific conceptualizations of GAD, with excessive and uncontrollable worry as its hallmark, many researchers have begun to identify the cognitive, behavioral, affective, and physiological processes involved in GAD. One of the many ways researchers have attempted to account for development and maintenance of GAD is by elucidating the nature of chronic, excessive, and uncontrollable worry (see, e.g., Borkovec et al., 1998 and Mennin et al., 2002; Roemer & Orsillo, 2002; Wells & Carter, 2001). Our own research has also focused, to some degree, on understanding the nature of pathological worry in order to develop and validate a cognitive-behavioral model of GAD (Dugas et al., 1997, Dugas et al., 2001b and Dugas et al., 1995b). The model, which has been described in detail elsewhere (i.e., Dugas, Gagnon, Ladouceur, & Freeston, 1998), posits that intolerance of uncertainty is a key factor involved in the development and maintenance of pathological worry and GAD. Previous research shows that intolerance of uncertainty is highly related to worry (Freeston, Rhéaume, Letarte, Dugas, & Ladouceur, 1994), and that the relationship between intolerance of uncertainty and worry is not the result of shared variance with general anxiety or depression (Dugas et al., 1997). Furthermore, in non-clinical populations, intolerance of uncertainty is more highly related to worry than to obsessions or panic symptoms (Dugas et al., 2001b), and worry is more highly associated with intolerance of uncertainty than with perfectionism, need for control, and intolerance of ambiguity (Buhr & Dugas, 2001). Research also shows that experimental manipulations of intolerance of uncertainty lead to changes in worry, with decreased intolerance of uncertainty leading to less worry, and increased intolerance of uncertainty leading to more worry (Ladouceur, Gosselin, & Dugas, 2000). Moreover, a recently completed study shows that intolerance of uncertainty is associated with enhanced recall of stimuli denoting uncertainty, and with more threatening interpretations of ambiguous situations (Dugas et al., in press), suggesting information processing pathways by which intolerance of uncertainty might lead to pathological worry. Of note, findings from the Dugas et al. (in press) study showed that threatening interpretations of ambiguous situations were more highly related to intolerance of uncertainty than to worry, anxiety or depression. Taken together, these data suggest that intolerance of uncertainty may be a sensitive and specific causal risk factor for GAD. This model also includes three other variables thought to be involved in GAD: positive beliefs about worry (or beliefs about the usefulness of worrying), negative problem orientation, and cognitive avoidance. Research from different sources shows that positive beliefs about worry such as “worrying helps to solve problems” or “worrying can directly alter events” are related to level of worry (Davey, Tallis, & Capuzzo, 1996b; Freeston et al., 1994; Shadick, Roemer, Hopkins, & Borkovec, 1991; Wells & Carter, 1999). Data from a recent GAD clinical trial also show that extent of change in positive beliefs about worry over treatment predicts the magnitude of change in pathological worry (Laberge, Dugas, & Ladouceur, 2000). The role of negative problem orientation (i.e., a set of dysfunctional attitudes toward social problem solving) in pathological worry has also received support from different sources. For example, Davey, Jubb, and Cameron (1996a) showed that changes in problem-solving confidence, a component of problem orientation, can have a causal effect on catastrophic worrying. Other studies show that pathological worry is related to negative problem orientation but unrelated to knowledge of problem-solving skills (Dugas et al., 1995b) or problem-solving ability (Davey, 1994). The final component of the model, cognitive avoidance, consists of a constellation of primarily internal strategies aimed at curtailing distressing thoughts and threatening images. Although our previous research has focused mainly on thought suppression as an avoidant strategy (Dugas et al., 1998; Ladouceur, Blais, Freeston, & Dugas, 1998; Ladouceur et al., 1999), we have begun to investigate the relationship between GAD and the tendency to use distraction, thought replacement, and thought suppression strategies, as well as the tendency to avoid concrete thoughts and situations that might trigger thoughts about feared outcomes. A number of important issues need to be addressed if we are to assess the relative merits of the cognitive-behavioral models of GAD. One of these issues is that of specificity. But should cognitive-behavioral models of GAD be specific to the worry of patients with GAD or should they also apply to the worry of patients with other anxiety disorders? Given that some experts in the field of anxiety have argued that GAD is the “basic” anxiety disorder and that understanding the processes involved in GAD has implications for understanding all anxiety disorders (Craske & Hazlett-Stevens, 2002; Roemer et al., 2002), it may be that models of GAD can help to understand the nature of worry in patients with other anxiety disorders. Thus, the most informative way of investigating the specificity of models of GAD may be to examine specificity both in terms of diagnosis and symptom constellations. The goal of the present study was to investigate the specificity of our model of GAD in two ways: (1) by comparing the model variables in two groups of anxiety disorder patients, i.e., patients with non-comorbid GAD and patients with non-comorbid panic disorder with agoraphobia (PDA); and (2) by examining the relationship between the model variables and worry, regardless of diagnostic status. The first hypothesis, which relates to diagnostic specificity, was that patients with GAD, relative to patients with PDA, would have higher levels of intolerance of uncertainty and a more negative problem orientation. This hypothesis was based on earlier research showing that patients with GAD were less tolerant of uncertainty and had poorer problem orientation than a mixed group of patients with other anxiety disorders (Ladouceur et al., 1999). The second hypothesis, which relates to symptom specificity, was that all model variables would be correlated with the central feature of GAD (i.e., worry) whereas none would be correlated with the main features of PDA (i.e., bodily sensations, agoraphobic cognitions, and behavioral avoidance) for the entire sample. Stated differently, it was predicted that the model of GAD would show moderate diagnostic specificity and high symptom specificity.