Objective: The authors sought to establish the natural course and risk-profile of depression, generalized anxiety disorder (GAD), and depression with co-existing GAD in later life.
Methods: A total of 2,173 community-living elderly persons were interviewed at baseline, and at a 3-year follow-up. The course of "pure" depression, "pure" GAD, and depression with coexisting GAD was studied in 258 subjects with baseline psychopathology. Authors assessed bivariate and multivariate relationships between risk factors and course types. The risk-profile for onset of pure depression, pure GAD, and the mixed condition at follow-up was studied in 1,915 subjects without baseline psychopathology.
Results: Remission rate at follow-up was 41% for subjects with depression-only, 48% for pure GAD, and significantly lower (27%) for depression with coexisting GAD. A pattern of temporal sequencing was established, with anxiety often progressing to depression or depression with GAD. Onset of pure depression and depression with co-existing GAD was predicted by loss events, ill health, and functional disability. Onset of pure GAD, and, more strongly, that of depression with coexisting GAD, was associated with longstanding, possibly genetic vulnerability.
Conclusions: In comparison with either depression-only or anxiety-only, the co-occurrence of these represents more severe and more chronic psychopathology, associated with longstanding vulnerability. In elderly persons, GAD often progresses to depression or to the mixed condition. These findings mostly favor a dimensional, rather than a categorical, classification of anxiety and depression.