Striatal Function in Generalized Social Phobia: A Functional Magnetic Resonance Imaging Study

BACKGROUND Although evidence suggests the involvement of the amygdala in generalized social phobia (GSP), few studies have examined other neural regions. Clinical, preclinical, and dopamine receptor imaging studies demonstrating altered dopaminergic functioning in GSP suggest an association with striatal dysfunction. This is the first functional magnetic resonance imaging (fMRI) study to use a cognitive task known to involve the striatum to examine the neural correlates of GSP. We examined whether subjects with GSP had differential activation in striatal regions compared with healthy control subjects while engaged in a cognitive task that has been shown to activate striatal regions reliably. METHODS Ten adult, unmedicated subjects with a primary DSM-IV diagnosis of GSP and 10 age-, gender-, and education-matched healthy comparison subjects underwent fMRI while performing the implicit sequence learning task. RESULTS The GSP and healthy comparison subjects did not differ significantly on the behavioral performance of the task. Subjects with GSP, however, had significantly reduced neural activation related to implicit learning compared with healthy comparison subjects in the left caudate head, left inferior parietal lobe, and bilateral insula. CONCLUSIONS These findings support the hypothesis that GSP is associated with striatal dysfunction and further the neurobiological understanding of this complex anxiety disorder.