What characteristics of primary anxiety disorders predict subsequent major depressive disorder?

Objective: The goal of this study was to examine the associations between specific anxiety disorders and the risk of major depressive disorder and to explore the role of various clinical characteristics of anxiety disorders in these relationships using a prospective, longitudinal design. Method: The data are from a 4-year prospective, longitudinal community study, which included both baseline and follow-up survey data on 2548 adolescents and young adults aged 14 to 24 years at baseline. DSM-IV diagnoses were made using the Munich-Composite International Diagnostic Interview. Results: The presence at baseline of any anxiety disorder (odds ratio [OR] = 2.2 [95% Cl = 1.6 to 3.2]) and each of the anxiety disorders (specific phobia, OR = 1.9 [95% CI = 1.3 to 2.8]; social phobia, OR = 2.9 [95% CI = 1.7 to 4.8]; agoraphobia, OR = 3.1 [95% CI = 1.4 to 6.7]; panic disorder, OR = 3.4 [95% CI = 1.2 to 9.0]; generalized anxiety disorder, OR = 4.5 [95% CI = 1.9 to 10.3]) was associated with a significantly (p > .05) increased risk of first onset of major depressive disorder. These associations remained significant after we adjusted for mental disorders occurring prior to the onset of the anxiety disorder, with the exception of the panic disorder association. The following clinical characteristics of anxiety disorders were associated with a significantly (p > .05) increased risk of developing major depressive disorder: more than I anxiety disorder, severe impairment due to the anxiety disorder, and comorbid panic attacks. In the final model, which included all clinical characteristics, severe impairment remained the only clinical characteristic that was an independent predictor of the development of major depressive disorder (OR = 2.2 [95% Cl = 1.0 to 4.4]). Conclusion: Our findings suggest that anxiety disorders are risk factors for the first onset of major depressive disorder. Although a number of clinical characteristics of anxiety disorders appear to play a role in the association between anxiety disorders and depression, severe impairment is the strongest predictor of major depressive disorder.