Considered by some to be the ‘basic’ anxiety disorder (Rapee, 1991), generalized anxiety disorder (GAD) is characterized by both cognitive (thought) and physical symptoms. People with GAD experience excessive anxiety and worry that is difficult to control about a number of life circumstances, particularly minor matters. The focus of worry may change frequently. Associated with the cognitive features of the disorder are three or more of the following physical symptoms: restlessness, fatigue, concentration problems, irritability, muscle tension, and sleep disturbance (American Psychiatric Association, 1994).
The physical component of GAD may constitute a defining characteristic of the disorder. A multi-site study of the symptoms of GAD found that people with GAD most commonly endorse symptoms of irritability, restlessness, muscle tension, difficulty concentrating, sleep difficulties, feeling keyed up, and easy fatigability (Marten et al., 1993). These symptoms reliably discriminate people with GAD from non-anxious controls (Hoehn Saric, McLeod, & Zimmerli, 1989) and from people with other anxiety disorders (Noyes et al., 1992).
Several studies have tried to identify causes of GAD. Although some persons with GAD report experiencing symptoms their whole lives, the mean age of onset of GAD seems to be in the mid-teens (Rapee, 1985; Rapee, 1991; Thyer, Parrish, Curtis, Nesse, & Cameron, 1985). This later age of onset is characteristic of many of the anxiety disorders and may simply be when anxiety symptoms first manifest themselves. Alternatively, this later age of onset may suggest that certain life experiences may be involved in the onset of the disorder, worsening of the disorder, or both.
Borkovec and Newman (1997) have speculated on early childhood experiences that may be associated with the later development of GAD. They suggest that persons with GAD are often caregivers for their parents and lack feelings of being cared for by them. The early role of a caregiver may communicate that the world poses dangers which one is unable to manage so that one must be hypervigilant and always anticipate danger (Woody & Rachman, 1994). Retrospective studies have supported this thesis. Persons with GAD are likely to form insecure attachments with and experience anger towards their caregivers and, as adults, toward close others (Cassidy, 1995; Zuellig, Newman, Kachin, & Constantino, 1997).
Life events more proximal than early childhood experiences have also been implicated in the onset of GAD. Analyses of traumas experienced by persons with GAD indicate that experiences of physical threat, defined as illness, injury, or death, accounted for 71% of traumas reported by persons with GAD (Molina et al., 1992). This is in contrast to findings on the nature of worry, which suggest that topics of chronic intense worry most commonly include life circumstances, particularly minor matters (Sanderson & Barlow, 1990). The juxtaposition of these findings led Borkovec and colleagues to speculate that worry may serve as a means of avoiding catastrophic thoughts or images associated with the experience of traumatic life events (e.g., Borkovec, 1994). That is, the predominance of worry evidenced by persons with GAD may function as an avoidance response, suppressing anxiety-related images, physical activation, and adaptive processing of emotion (Borkovec et al., 1993). Borkovec and Roemer (1995) compared self-ratings of reasons for worry of persons with GAD, persons who are non-worried but anxious, and controls. Persons with GAD were discriminated from the other two groups because they gave higher ratings of ‘distraction from more emotional topics’ as a reason for their worry.
Beck and Emery (1985) hypothesize that, in addition to other developmental factors, anxiety and worry are precipitated by an appraisal of threat, increasing environmental demands, and stressful life events. Cognitive models of threat or danger cause the person to attend to information that is consistent with those models and to ignore information that is not. Information that is ambiguous or unrelated to threat may also trigger the person’s threat model, thereby leading to worry.
Barlow (1988) proposes that anxious apprehension, a biological and psychological vulnerability to anxiety, is the core feature of all anxiety disorders. According to Barlow, GAD, marked by arousal-driven worry, is distinct from other anxiety disorders in that panic attacks do not serve an causal role. Rather, Barlow conceptualizes GAD as chronic, intense, diffuse, uncontrollable worry marked by an inability to focus one’s attention. Additionally, he argues that “increasing vulnerabilities to anxiety insure that relatively small disruptions in one’s life (hassles) become the focus of anxious apprehension, resulting in a number of shifting, excessive, unreasonable worries” (Barlow, 1988, p. 579). In this way, Barlow suggests that ‘hassles’ can and do serve as maintaining factors. Such stressors, which may change in content over time, trigger stress reactions, which are interpreted as unpredictable and uncontrollable. Heightened physiological and psychological arousal and negative affect characterize stress reactions, the occurrence of which may lower the threshold for subsequent stress reactions. A cycle of worry ensues in which the person oscillates between worrying about the unpredictability of life events and the uncontrollability of their worry. Attention is necessarily removed from environmental cues, some of which may have served to counter the cognitive interpretations of the worry-provoking events. Thus, once the cycle begins, it can become self-perpetuating and leads to increased impairment.