Abstract
Recent longitudinal epidemiological studies suggest that anxiety disorders usually precede the onset of depressive disorders and might be regarded as risk factors for secondary depressive disorders. This paper reviews the available evidence, which suggests that generalized anxiety disorder (GAD) is a temporally primary anxiety disorder, preceding the onset of depression.
In retrospective studies, like other anxiety disorders, GAD in adulthood and among adolescents has been reported to precede the onset of depressive disorders in the majority of cases. Prospective longitudinal data suggest that GAD is associated with an increased risk of an earlier first onset of depression. Comparisons with panic disorder reveal that GAD cases predominantly develop depression after 2–4 years, whereas the majority of cases of panic disorder develop depression within a year after onset. These observations suggest differences in the pathogenesis of both conditions, which require further investigation. The comorbidity between GAD and major depression and the fact that temporally primary GAD significantly predicts a subsequent onset of depression raise the question of whether early intervention and treatment of primary GAD would effectively prevent the subsequent first onset of depression. Copyright © 2001 Whurr Publishers Ltd.