The latent structure of social anxiety disorder: consequences of shifting to a dimensional diagnosis.

Despite longstanding debate over the nature of the boundary between social anxiety disorder (SAD) and less severe social anxiety, no study has tested directly whether the defining features of the disorder correspond to a latent category or dimension. The present study examined this question using data from the National Comorbidity Survey Replication (NCS-R), a nationally representative survey of the U.S. household population. Indicators representing the Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV; American Psychiatric Association, 1994) criteria for SAD were submitted to taxometric analyses in a subsample of adults (n = 2,166) who reported excessive social fear in their lifetime. Multiple taxometric procedures and consistency tests converged on a dimensional solution, suggesting that SAD is continuous with milder social anxiety. In follow-up analyses, a dimensional SAD diagnosis outperformed the DSM-IV diagnosis in predicting the subsequent onset of a range of clinically important outcomes. Large differences in associations with comorbid mood disorders, suicidality, and treatment seeking in particular favored the prognostic value of dimensional over categorical diagnosis. These findings support the validity and potential utility of a dimensional conceptualization of SAD that may inform efforts to revise the diagnosis for DSM-V.