The social anxiety spectrum.

Social anxiety disorder is well suited to the spectrum concept because it has trait-like qualities of early onset, chronicity, and no empirically derived threshold that demarcates normal from clinically significant trait social anxiety. Social anxiety disorder has been shown to respond to relatively specific pharmacologic and cognitive-behavioral therapies, which makes identification of other conditions that may lie on the social anxiety disorder spectrum important because of possible treatment implications. Biologic markers associated with social anxiety disorder also may be shared by similar but nonidentical traits, such as behavioral inhibition and detachment. Clarification of the trait spectrums associated with specific biologic systems offers an opportunity for improving the understanding of the origin of these conditions. Strong evidence exists that at least some forms of shyness, avoidant personality disorder, and selective mutism lie on a social anxiety disorder spectrum. For several other disorders that share a prominent focus on social comparison, significant subgroups of patients seem to have features of social anxiety disorder. These disorders include major depression (especially the atypical subtype), body dysmorphic disorder, and eating disorders. Several other disorders marked by social dysfunction or inhibition, including substance use disorders (especially alcoholism), paranoid disorder, bipolar disorder, autism, and Asperger's disorder, also may show some overlap with social anxiety disorder features (e.g., social anxiety as a cause or complication of substance abuse, social avoidance in paranoid disorder, social disinhibiton in bipolar disorder, and social communication deficits in autism and Asperger's disorder). Social anxiety disorder also is associated with other anxiety disorders in general and other phobias in particular. In respect to traits, a growing body of evidence links behavioral inhibition to the unfamiliar to a social anxiety disorder spectrum with some specificity. Biologic measures of dopamine system hypoactivity have been linked to social anxiety disorder, trait detachment, and general deficits in reward and incentive function. It remains to be clarified, however, whether this brain system function is best characterized by a social anxiety disorder spectrum or some variant that incorporates social reward deficits or social avoidance behavior. Social anxiety disorder, shyness, and behavioral inhibition all seem to have a genetic component, but more research is needed to attempt to identify a more specifically heritable temperament associated with these conditions. Finally, the emergent concept of a social anxiety spectrum needs maturation. Although the notion of a single social anxiety disorder spectrum currently has some clinical use, the authors believe that exclusive focus on the notion of a single continuum with two extremes--from social disinhibition in mania to the most severe form of social anxiety, avoidant personality disorder--is premature and limiting in respect to etiologic research. An alternative approach is to conceptualize multiple, probably overlapping spectra in this area of social psychopathology. Individual dimensions might be based on various core phenomenologic, cognitive, or biologic characteristics. A bottom-up biologic approach holds promise for identifying spectra with a common etiology that might respond to specific treatments. Taking a pluralistic view of the concept of spectrum at this stage may help accelerate our understanding of social anxiety and related disorders.