The Natural History of Generalized Anxiety Disorder: A Review

Catherine L. Woodman, MD

Disclosures

Medscape Psychiatry & Mental Health eJournal. 1997;2(3) 

In This Article

Course

Barlow[30] speculated that GAD was a more chronic and severe disorder than panic disorder. He hypothesized that GAD, with its earlier age of onset, longer course, and less robust response to treatment than other anxiety disorders, could cause greater disruption in subjects' lives than other anxiety disorders. Unfortunately, few studies have examined the course of GAD and patients' response to treatment. Follow-up studies done prior to 1980 are problematic, because it is unclear what percentage of the patients had GAD versus panic disorder. It is assumed that, using current criteria, a majority of patients in these studies would be diagnosed with panic disorder, because most studies used treatment-seeking populations, and these populations are inclined to have more severe illness. Therefore, conclusions about the nature of GAD gathered from these studies should be made cautiously.

A number of GAD follow-up studies completed after 1980 fulfill the minimum criteria for validity as outlined by Greer[31] in 1969: (a) an unselected series of patients with anxiety states followed up after at least 1 year; (b) outcome ascertained in at least 75% of the original sample; and © follow-up information obtained by personal interview. The information gathered from these studies demonstrated, for the most part, that anxiety disorders have a chronic, fluctuating course.[32,33,34,35,36] Although some patients experience exacerbations and remissions, the percentage is low. In one follow-up investigation, 24% of anxious medical patients reported symptom-free intervals, but only 12% were symptom-free at the time they were reinterviewed.[32] While full recovery is unusual, roughly 50% of patients were improved at follow-up.[31,34] One study found lower socioeconomic status associated with poorer outcome.[32]

The 1-year follow-up data from the Environmental Catchment Area (ECA) study, done in 1980, found that the recovery rate for GAD (defined as no longer meeting criteria for GAD, rather than being free of symptoms) was 56%.[37] This figure--the second highest reported in this study for any psychiatric disorders--is hard to evaluate, because poorly defined criteria were used (DSM-III), and coexisting disorders were not excluded and not taken into account. Nevertheless, data from the ECA study suggest that GAD may last for decades, if not a lifetime, in many patients.[38] Unfortunately, GAD was diagnosed at only 3 of the 5 sites involved in the study, but data from these sites revealed an average duration of illness between 6.5 and 10.4 years. Indeed, 40% of patients reported the presence of symptoms for more than 5 years, and more than 10% had symptoms for longer than 20 years. Although the researchers noted that the onset of GAD could occur at any time during life, more than 35% of patients with panic disorder or phobia in the same study dated the onset of "being a nervous person" at age 10 or younger, which suggests that excessive worry and anxiety in patients with anxiety disorders may begin in childhood and eventually reach syndromal levels many years later, perhaps due to inevitable role changes and stresses during life.[39]

Mancuso and associates[40] followed up with 50 patients 16 months after initial evaluation. They reinterviewed 88% of probands and found that 50% had remitted and 50% met criteria for GAD. They found that no patients developed disorders that they had not had at baseline during the follow-up period. This study lends limited support to the diagnostic classification of GAD, but only limited conclusions can be drawn from these data because the researchers did not attempt to quantify persistent symptoms in probands who did or did not meet criteria for GAD.

Rickels and colleagues[41,42] reviewed the literature on GAD related to treatment and outcome and found that the available information suggests that GAD has a chronic course, with significant long-term distress and morbidity. They conducted a 40-month follow-up study with patients who met DSM-III-R criteria for GAD. They reinterviewed 75% of patients and found that 58% of the clorazepate-treated group and 25% of the buspirone-treated group reported moderate to severe anxiety symptoms and illustrated, in a prospective manner, the chronic nature of GAD. There was no significant difference in outcomes between the 2 treatment groups.

Woodman and coworkers[43] studied 64 patients with GAD and 68 patients with panic disorder, comparing diagnostic stability and course and outcome of GAD, as contrasted with panic disorder. They were interviewed an average of 5 years (range, 3 to 7 years) after their enrollment in drug treatment studies and were treated naturally thereafter (ie, no structured treatment over follow-up period). At baseline, the GAD group was significantly older and had more education, earlier onset, and longer duration of illness than subjects with panic disorder. GAD subjects also had less severe symptoms, as measured by both clinician-rated and self-rated instruments. At follow-up, there was diagnostic stability for both GAD and panic disorder. Significantly fewer GAD subjects achieved partial or full remission at follow-up (37% vs 63%). On measures of the symptoms and severity of anxiety, GAD probands were not different from panic disorder probands at follow-up.

Although GAD appears to be a less severe disorder than panic disorder at the time that patients seek treatment, it has an earlier onset and a more chronic course than panic disorder. It may also be less responsive to naturalistic treatment. The limited data available related to the course and outcome of GAD clearly distinguish it from panic disorder and support its diagnostic validity.

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