Admixture analysis of the diagnostic subtypes of social anxiety disorder: Implications for the DSM-V

Background and objectives: Much controversy exists regarding diagnostic subtypes of social anxiety disorder (SAD). The present study used admixture analysis to examine whether individuals with generalized and nongeneralized SAD belong to the same or different populations of origin. This can inform diagnostic subtyping of SAD in the forthcoming DSM-V. Methods: Treatment-seeking individuals with generalized SAD (n = 154) and nongeneralized SAD (n = 48) completed a battery of questionnaires. Based on participants' responses to the Liebowitz Social Anxiety Scale (LSAS), we estimated log likelihood and chi-square goodness-of-fit for models with 1, 2, 3, or 4 populations of origin, and compared models using forward stepwise estimation and maximum likelihood ratio tests. Results: Admixture analyses suggested that the two diagnostic subtypes of SAD belong to the same underlying population of origin. In addition, observable differences in depression, general anxiety, and comorbidity were no longer significant when controlling for social anxiety severity. Limitations: Our sample was recruited in the U.S. and was a treatment-seeking sample. Future studies should examine whether our results generalize to different cultures, and community samples. Conclusions: Support for qualitative differences between SAD subtypes was not found. Rather, our findings support the notion that the diagnostic subtypes of SAD differ quantitatively, and that SAD exists on a continuum of severity. This finding informs diagnostic subtyping of SAD in the forthcoming DSM-V.