These changes in diagnostic criteria led to delays in cumulating data on the epidemiology of generalized anxiety disorder. Additional changes in the definition of excessive worry and the required number of associated psychophysiological symptoms were made in the DSM-IV. This change was implemented in the final version of the DSM-III-R. Based on this finding, the DSM-III-R committee on generalized anxiety disorder recommended that the duration required for the disorder be increased to six months. The rate of comorbidity of generalized anxiety disorder with other disorders decreases as the duration of generalized anxiety disorder increases. Comorbidity of generalized anxiety disorder and major depression was especially strong and led some commentators to suggest that generalized anxiety disorder might better be conceptualized as a prodrome, residual, or severity marker than as an independent disorder. Early clinical studies evaluating DSM-III, according to this definition, found that the disorder seldom occurred in the absence of another comorbid anxiety or mood disorder. Several related psychophysiological symptoms were also required for a diagnosis of generalized anxiety disorder. The DSM-III definition of generalized anxiety disorder required uncontrollable and diffuse (i.e., not focused on a single major life problem) anxiety or worry that is excessive or unrealistic relative to objective life circumstances and persists for one month or longer. A recognition that generalized anxiety disorder and panic, although often occurring together, are sufficiently distinct to be considered independent disorders, led to their separation in the DSM-III.
Before that time, generalized anxiety disorder was conceptualized as one of the two core components of anxiety neurosis, the other being panic. The American Psychiatric Association first introduced the diagnosis of generalized anxiety disorder two decades ago in the DSM-III. The prevalence is approximately twice as high among women as among men. General prevalence in children younger than 18 years is between 5.7% and 12.8%. However, the lifetime prevalence of a severe anxiety disorder in children ages 13 to 18 is approximately 6%. Childhood anxiety occurs in about 1 in 4 children at some time between the ages of 13 and 18 years.