Parietal abnormalities are related to avoidance in social anxiety disorder: A study using voxel-based morphometry and manual volumetry

•To assess structural brain changes related to the DMN in individuals with SAD.•The results indicate parietal and premotor cortex abnormalities in SAD.•Social avoidance severity is related to parietal abnormalities in SAD.

Evidence is accumulating that various mental disorders are related to neural abnormalities in the parietal cortices that are associated with the default mode network (DMN). Participants comprised 67 persons with social anxiety disorder (SAD) and 64 matched healthy controls who underwent structural magnetic resonance imaging (MRI) and a comprehensive clinical assessment. Voxel-based morphometry (VBM) across the entire brain and manual volumetry of the parietal cortices were performed. The results indicate abnormal manually segmented volumes or gray matter (GM) volumes within the precuneus, postcentral gyrus and inferior parietal cortex, as well as in the premotor cortices including the supplementary motor cortex. Significant negative correlations were obtained between parietal, especially precuneus, abnormalities and social avoidance severity, indicating stronger avoidance in SAD participants with smaller volumes or less GM. We conclude that pathological avoidance behaviors in SAD are associated with structural deficits of parietal regions that are associated with the DMN, which has been shown to mediate introspection and reflection upon one׳s own mental state in healthy humans.