Generalized anxiety disorder: What are we missing?
Introduction
Anxiety disorders are considered to be the most prevalent of psychiatric disorders, with generalized anxiety disorder (GAD) believed to be one of the most common in the primary care setting (Wittchen et al., 2002). Indeed, GAD is present in nearly one-quarter of patients complaining of an anxiety condition to their primary care physician (PCP) (Wittchen et al., 2002). Regardless of this, many challenges in recognizing and treating GAD patients remain, most especially in primary care. In fact patients suffering with this anxiety disorder are as likely to initially seek out their PCP, than a psychiatrist, for the treatment of numerous associated somatic ailments, such as joint pain, weariness, or weight loss (Shear and Schulberg, 1995). Patients with an anxiety disorder are also more likely than other patient groups to make frequent medical appointments, undergo extensive medical investigations (Katon et al., 1992), present with medical and psychiatric comorbidities (Bowen et al., 2000, Noyes, 2001, Harter et al., 2003), report poor health, smoke cigarettes, and abuse other substances (Shader and Greenblatt, 1993). Physicians are also missing much of the clinical study data required to make a valid diagnosis of GAD, although a similar situation exists for many of the other mood and anxiety disorders. The name of the disorder may also be misleading—the focus of the condition is the cognitive dysfunction, which Karl Rickels eloquently refers to as an “intolerance of uncertainty.” Perhaps an alternative name would more appropriately emphasize the specific symptoms associated with the disorder. All of these factors, to different degrees, compound the difficulty of the physician's task—that of assuring an accurate diagnosis (Stein, 2001).
GAD was first classified as a distinct disorder relatively recently, in 1980 (American Psychiatric Association, 1980). Previously little distinction was made between GAD and panic disorder (PD)—they were conceptualized as the core components of anxiety neurosis. The realization that GAD and PD are sufficiently different to be considered independently led to their separation in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) (American Psychiatric Association, 1994). Having evolved from a residual syndrome with several nonspecific features into a more precisely defined condition, GAD is characterized by continual worry and tension about daily life events that are pervasive and uncontrollable, rather than by specific fears. GAD is notable by the duration (≥ 6 months), incidence, and the intensity of apprehension concerning an event being far out of proportion to the actual probability or impact of the experience (Sanderson and Barlow, 1990, Allgulander, 2001, Kessler et al., 2001a). The impairment should also be judged as not attributable to medication, another illness, or substance abuse. Further details of the DSM-IV criteria for the diagnosis of GAD are detailed in Table 1. The condition is accompanied by psychic symptoms such as restlessness, poor concentration, or irritability, and somatic symptoms including fatigue, muscle tension, and sleep difficulties (Allgulander et al., 2003). Indeed, in the PCP's office, this constellation of symptoms can look like the symptoms of numerous other medical conditions. Unfortunately, with only limited time to examine for additional symptoms and minimal acquaintance with psychiatric diagnoses, the PCP will often treat the presenting symptom, but miss the comprehensive diagnosis.
Section snippets
Diagnosis
In Europe, diagnosis is currently based upon the World Health Organization's (WHO's) Tenth International Classification of Diseases (ICD-10) (World Health Organization, 1992), while the DSM-IV classification is used in the USA generally and in Europe for research purposes. The DSM-IV emphasizes the psychic component (e.g., worry) rather than the somatic (e.g., muscle tension) or autonomic symptoms (e.g., diaphoresis or increased arousal) (American Psychiatric Association, 1994).
On initial
Genetic epidemiology
The decision to categorize GAD as an independent condition has also been reinforced through studies of the inheritability of anxiety and mood disorders. Initial studies investigating the genetic characteristics of GAD found a higher frequency of GAD among first-order relatives of probands with GAD than among relatives of non-GAD controls (Noyes et al., 1987). More recent research has also supported an obvious familial aggregation, with studies in twins showing genetic factors to be no less
Prevalence
The changing and differing diagnostic criteria employed might be assumed to have complicated the accumulation of data on the prevalence of GAD; however, the reported frequency is surprisingly consistent. The US National Comorbidity Survey (NCS) and the National Institute of Mental Health (NIMH) Epidemiological Catchment Area (ECA) Program, using DSM criteria, estimated 12-month occurrence at 3.1% and 3.8%, respectively, and lifetime occurrence 5.1% and 4.1–6.6%, respectively (Blazer et al., 1991
Comorbidity
Symptoms of anxiety appear across many psychiatric diagnoses. Maybe as a result of this, the diagnosis of GAD is often recorded as a comorbid condition with another psychiatric disorder, or the symptoms are simply attributed to another disorder, most often major depressive disorder (MDD). Epidemiologic data from the NCS indicated that 90% of GAD patients had another lifetime psychiatric diagnosis, particularly an affective disorder, and only one-third of individuals with a current GAD episode
Duration of illness and clinical course
GAD follows a chronic course and may be either constant or fluctuating. Patients typically suffer symptoms for a number of years before being diagnosed and effectively treated, with retrospective studies suggesting symptoms may wax and wane for up to 20 years (Brawman-Mintzer and Lydiard, 1996, Bruce et al., 2001, Keller, 2002). The Harvard/Brown Anxiety Research Program (HARP), a naturalistic, longitudinal study that assessed patients, with PD, PDA, SP, and GAD, at 6–12-month intervals over
Burden of disability
It used to be thought that GAD, in the absence of other disorders, was associated with a low level of disability. However, the chronic nature of GAD means that the condition imposes a substantial individual burden. This may manifest in the quality and level of functioning in social and occupational interactions, resulting in significant though indirect costs to society. This burden is most notable in terms of substantial impairments resulting in days where a sufferer is restricted from or
Primary care
Consistently, data support the fact that GAD patients are often present in the primary care setting. GAD is the anxiety disorder most frequently encountered by PCPs, being present in nearly one-quarter of patients complaining of anxiety problems. One primary care study reported pure GAD patients as having twice as many visits to their PCP as patients with depression (Wittchen et al., 2002). It also reported that the GAD patients had significantly more visits to their PCP, even when the data
Education
Why do PCPs not recognize or diagnose GAD? It is not due to a lack of interest, nor due to the diagnostic criteria; unfortunately, it is due to a lack of time and training. PCPs simply do not have time to sit with their patient and talk through their symptoms fully or to meet with relatives to confirm changes in a patient's behavior. Undoubtedly, the chronic nature of GAD may make it difficult for the symptoms to ‘stand out’ and be detected easily. GAD is disproportionately present in patients
Conclusions
GAD is an identifiable anxiety disorder that is associated with a significant burden of disability, the scale of which is comparable to that of MD. GAD, as a condition, has much in common with MD, with the majority of GAD patients developing a secondary depression at some point. Indeed, often the reason why these patients present to their physician is due to the development of such a depressive episode. Early detection of GAD should, therefore, be encouraged, for example, by the use of posters
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