Anxiety sensitivity within the anxiety disorders: Disorder-specific sensitivities and depression comorbidity

Abstract

The tendency to perceive anxious states as aversive and harmful is hypothesized to confer vulnerability to the development of anxiety disorders. The most commonly used measure of anxiety sensitivity, the Anxiety Sensitivity Index [ASI; Reiss, S., Peterson, R.A., Gursky, D.M., & McNally R.J. (1986). Anxiety sensitivity, anxiety frequency, and the prediction of fearfulness. Behavior Research and Therapy, 24, 1–8], is composed of multiple lower-order factors, assessing fear of physical symptoms, fear of publicly observable anxious symptoms, and fear of cognitive dyscontrol. This study examined the convergent validity of the lower-order anxiety sensitivity dimensions in DSM-IV diagnosed anxiety disorders. Participants with primary diagnoses of panic disorder with agoraphobia, social phobia, and generalized anxiety disorder (GAD) completed the ASI and measures of anxiety and depression severity. Support was found for the convergent validity of all ASI dimensions in reference to thematically related anxiety disorders and in the identification of patients presenting with and without secondary major depressive disorder (MDD). The ASI-fear of cognitive dyscontrol dimension displayed strong and nonredundant associations with GAD, dimensional depression scores, and secondary diagnoses of MDD. The conceptual implications of the shared importance of fear of cognitive dyscontrol in GAD and MDD are discussed.

Introduction

Anxiety sensitivity refers to the fear of anxiety symptoms as a result of beliefs about their perceived harmful physical, social or psychological consequences (Reiss, 1987; Reiss & McNally, 1985; Reiss, Peterson, Gursky, & McNally, 1986). The initial conceptualization (Reiss & McNally, 1985) and operationalization of the anxiety sensitivity construct with the 16-item Anxiety Sensitivity Index (ASI; Reiss, Peterson, Gursky, & McNally, 1986), promoted a unitary view of vulnerability for the development and maintenance of anxiety and panic. Early studies demonstrated that ASI scores distinguish between individuals with and without a lifetime history of panic attacks (for review, see Norton, Cox, & Malan, 1992), and between individuals experiencing panic attacks versus those with bona fide panic disorder (Cox, Endler, & Swinson, 1991). Further, patients with panic disorder were found to have higher ASI scores than all other anxiety disorder groups except post-traumatic stress disorder (PTSD) (Taylor, Koch, McNally, & Crockett, 1992). As such, there is considerable empirical support for the importance of anxiety sensitivity in the pathogenesis of panic disorder (for review, see Taylor, 1999). The current research aimed to provide further tests of the role of anxiety sensitivity in anxiety disorders presenting with and without depression comorbidity.

The unitary view of anxiety sensitivity was supported by early psychometric examinations of the ASI that found a uni-dimensional factor structure (e.g., Reiss, Peterson, Gursky, & McNally, 1986). Subsequently more extensive examinations of the ASI have resulted in an emerging consensus that the ASI, and the anxiety sensitivity construct, is composed of a unifactorial structure at the higher-order level and a multifactorial structure at the lower-order level. While factorial studies of the 16-item ASI have extracted between two and four second-order factors, the modal solution converges on three (See Taylor, 1999 for review). While there is some variability in the factor names, the three replicable factors reflect: (1) fear of physical symptoms (ASI-Physical), (2) fear of publicly observable anxiety symptoms (ASI-Social) and (3) fear of cognitive dyscontrol (ASI-Cognitive), respectively.

To date, there has been only minimal research examining the convergent validity of the lower-order ASI dimensions within patient groups with anxiety disorders. Zinbarg, Brown, and Barlow (1997) demonstrated that patients with DSM-III-R diagnosed panic disorder with/without agoraphobia (PD/A) had comparatively greater score elevations on ASI-Physical compared to patients with generalized anxiety disorder (GAD), social phobia (SP), obsessive-compulsive disorder (OCD), simple phobia and nonaffected controls. Further, ASI-Social scores were highest in the SP group and were also significantly higher than in the PD (but not PD/A), GAD, OCD, simple phobia and nonaffected control groups. No hypotheses were established regarding the possible convergent validity of the ASI-Cognitive scale and no differences were observed between patients with PD/A, GAD, or OCD, although all three groups had higher scores than patients with SP and simple phobia, as well as nonaffected controls. Despite different factor loadings, Blais et al., 2001 obtained similar findings regarding the convergent validity between ASI-Physical scores and PD and between ASI-Social scores and SP, although groups did not differ on the ASI-Cognitive dimension.

Rodriguez and colleagues (Rodriguez, Bruce, Pagano, Spencer, & Keller, 2004) employed a series of multiple regression analyses to determine whether DSM-III-R diagnosed anxiety disorders were predictive of the different ASI dimensional scores. The PD/A diagnosis uniquely predicted ASI-Physical scores, the SP diagnosis predicted ASI-Social scores (as did GAD and MDD diagnoses), and the GAD diagnosis predicted ASI-Cognitive scores (as did SP and MDD diagnoses). With respect to the latter, whereas Zinbarg, Brown, and Barlow (1997) found ASI-Cognitive scores to be higher in patients with GAD than SP and simple phobia, Rodriguez, Bruce, Pagano, Spencer, & Keller, 2004 found that ASI-Cognitive scores were most strongly associated with GAD. The cognitive dyscontrol items of the ASI-Cognitive dimension, such as “When I cannot keep my mind on a task, I worry that I might be going crazy” or “When I am nervous, I worry that I am mentally ill,” appear consistent with the commonly reported cognitive appraisals of worry in GAD (Wells, 1997, p.202) and the empirically demonstrated spontaneous automatic thoughts of “mental catastrophe” typical of patients with GAD during anxious arousal (Breitholtz, Westling, & Öst, 1998).

Moreover, the item content of the ASI-Cognitive dimension overlaps considerably with the content of measures assessing anticipated danger associated with perceived uncontrollable cognitive processes, or negative meta-beliefs about worry (Wells, 2005). Negative meta-beliefs about worry have, in turn, been found to discriminate between nonanxious, nonworried-anxious, and GAD participants (80% correct classification) (Davis & Valentiner, 2000) and between high worriers with and without GAD (Ruscio & Borkovec, 2004). Negative meta-beliefs (i.e., perceived uncontrollability) about thought processes have also been found to be associated with depression (Papageorgiou & Wells, 2003). Interestingly, there is an even greater extant literature linking ASI-Cognitive scores to dimensional depression scores in anxious (Schmidt, Lerew, & Joiner, 1998; Taylor, Koch, Woody, & McLean, 1996; Zinbarg, Brown, Barlow, & Rapee, 2001) and depressed (Cox, Enns, Murray, Freeman, & Walker, 2001) clinical samples as well as nonclinical samples (Deacon, Abramowitz, Woods, & Tolin, 2003). These findings have led investigators to conclude that fear of mental dyscontrol represents a “depression-specific form of anxiety sensitivity” (Cox, Enns, & Taylor, 2001; Taylor, Koch, Woody, & McLean, 1996).

A central problem in establishing the convergent validity of the ASI dimensions in patient participants with anxiety disorders is that approximately 50–55% of patients with a principal anxiety disorder have at least one additional anxiety or depressive disorder at the time of assessment (Brown & Barlow, 1992; Barlow, 2002). This problem may be especially pertinent for the examination of the convergent validity of the ASI-Cognitive dimension since among patients with GAD, approximately 65% present with comorbid conditions, with the most common additional diagnoses being SP (22%) and major depression (20%) (Barlow, 2002, p. 310). An alternative approach would include the examination of the ASI dimensions in clinical samples based on the patient's principal diagnosis, irrespective of the presence of secondary diagnoses, while also controlling for general depression and anxiety severity. Given the strong association between ASI-Cognitive scores and depression, this approach would offer an especially rigorous test of whether ASI-Cognitive scores are associated with GAD while controlling for the shared variance with depression severity. Moreover, it would be of special significance if ASI-Cognitive scores were found to be associated with GAD and MDD given that ASI-Cognitive items do not overlap with any of the diagnostic criterion of these disorders (APA, 2000).

It was hypothesized that the ASI dimensions would be associated with thematically related anxiety disorders: ASI-Physical would be higher in patients with PD/A compared to other disorders, ASI-Social would be higher in patients with SP than in the other disorders, and ASI-Cognitive would be higher in patients with GAD than in the other anxiety disorders, when controlling for nonspecific symptoms of depression and anxiety severity. It was also hypothesized that ASI-Cognitive would be uniquely associated with depression severity scores and distinguish patients with and without secondary major depressive disorder.