The diagnostic frontiers of social anxiety disorder (SAD) are still controversial, since it could be described as part of a continuum of severity rather than as a disorder based on an arbitrary threshold with qualitative distinctions. The present study aims to investigate possible differences among subjects along the social anxiety spectrum using the Simulated Public Speaking Test (SPST), an experimental model of human anxiety. Afterwards, the anticipatory measures of SPST among groups were correlated with different volume of gray matter areas by MRI using the voxel-based morphometry method.

We evaluated patients with generalized SAD (n=25), subjects with subclinical SAD (with fear of a social situation without avoidance or impairment; n=14) and healthy controls (n=22).

The subjective SPST findings showed that avoidance and functioning impairment were due to a negative self-evaluation in SPST and not to the level of anxiety experienced. When all groups were pooled together, there was a positive correlation between levels of anxiety experienced and the volume of the right amygdala. The negative self-evaluation of performance in the SPST was associated with a reduction in the volume of the anterior cingulated complex (ACC) only in the SAD group.

These results suggest that the association between anxiety and amygdala volume may be a part of a continuum of social anxiety. However, the correlation between self-evaluation of performance with reduced ACC volume only in the SAD group does not support the idea that this association may be also part of a continuum.