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

Epidemiology

The essential feature of GAD is excessive or pathologic worry. Although subjects with GAD may not be able to identify their worrying as excessive, they do report that the constancy of this feeling causes them distress, is difficult to control, and has an impact on their life secondary to the objects of their worry. Among a number of population studies using various diagnostic criteria, estimates of the lifetime prevalence of GAD have ranged between 4.0% and 6.6%.[7,8,9,10]

Perhaps the best epidemiologic data on GAD come from one of these reports, which was based on data collected in the National Comorbidity Survey (NCS).[10] The NCS was a general population survey of noninstitutionalized American civilians 15 to 54 years of age. The study was quite large (N=8098) and utilized the most current DSM-III-R criteria available at that time. The results were reported with and without diagnostic hierarchical rules. In the absence of such exclusions, the prevalence of GAD in the total sample was 1.6% for current GAD (defined as a 6-month period of anxiety that continued in the 30 days prior to the interview), 3.1% for GAD within the previous 12-month period, and 5.1% for lifetime GAD.

Regardless of the time frame, there was a clear predominance of women with GAD, with a 2:1 female/male ratio. The prevalence was lowest in the youngest age group and increased with age: The prevalence in women aged 45 and older was 3.5% for those with current GAD and 10.3% for lifetime occurrence of GAD. Prevalence estimates did not change significantly when diagnostic hierarchical rules were imposed to exclude respondents whose GAD occurred exclusively during episodes of a mood or psychotic disorder--only 8% of subjects with GAD reported symptoms exclusively during episodes of another disorder. The researchers found that homemakers and unemployed respondents (mostly permanently disabled individuals and early retirees) had a significantly higher prevalence of GAD than other subjects.

There was a significant regional difference in GAD as well, with a higher lifetime prevalence in the Northeast than in other parts of the country. Predictors that were not found to be significant in this study included education, marital status, and urbanicity. Importantly, the researchers investigated potential differences between patients without psychiatric comorbidity (ie, primary GAD--in patients with an earlier onset of GAD compared with their comorbid psychiatric disorder) and secondary GAD (ie, a later age of GAD onset than the comorbid psychiatric disorder).They found no differences between these groups with regard to age, sex, race, or social class, lending validity to the independent status of GAD.

Noyes and colleagues[11] reported a study of GAD and panic disorder in a treatment-seeking population and found significant differences between the groups. They found that patients with GAD had a significantly earlier age of onset, as well as more psychologic symptoms and fewer physiologic symptoms than patients with panic disorder. The GAD subjects were older at the time that they sought treatment, and fewer had been treated in the past. The investigators noted significant comorbidity with psychiatric disorders, and the patterns were different from those seen in the panic-disorder patients. The authors of this article noted that, while the study supported a distinction between the 2 disorders as well as diagnostic validity for GAD, the importance of GAD may not be so much the disorder itself as its tendency to accompany other disorders.

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