Background
Although often considered of minor significance in themselves, evidence exists that early-onset phobic disorders might be predictors of later more serious disorders, such as major depressive disorder (MDD). The purpose of this study was to investigate the association of phobic disorders with the onset of MDD in the community in Japan.
Methods
Data from the World Mental Health Japan 2002-2004 Survey were analyzed. A total of 2,436 community residents aged 20 and older were interviewed using the WHO Composite International Diagnostic Interview 3.0 (response rate, 58.4%). A Cox proportional hazards model was used to predict the onset of MDD as a function of prior history of DSM-IV specific phobia, agoraphobia, or social phobia, adjusting for gender, birth cohort, other anxiety disorders, education, and marital status at survey.
Results
Social phobia was strongly associated with the subsequent onset of MDD (hazard ratio [HR] = 4.1 [95%CI: 2.0-8.7]) after adjusting for sex, birth cohort, and the number of other anxiety disorders. The association between agoraphobia or specific phobia and MDD was not statistically significant after adjusting for these variables.
Conclusions
Social phobia is a powerful predictor of the subsequent first onset of MDD in Japan. While this finding argues against a simple neurobiological model and in favor of a model in which the cultural meanings of phobia play a part in promoting MDD, an elucidation of causal pathways will require more fine-grained comparative research.