Anterior cingulate neurochemistry in social anxiety disorder: 1H-MRS at 4 Tesla.

Recent studies suggest exaggerated responses in the limbic system of patients with generalized social anxiety disorder in response to threat/anxiety-related social situations and aversive conditioning, processes mediated by the glutamatergic system. This single-voxel, high-field 1H-magnetic resonance spectroscopy study examined concentrations of glutamate, and other metabolites, in the anterior cingulate cortex and occipital cortex (control region) of 10 medication-naive patients with generalized social anxiety and 10 matched healthy comparison subjects. Glutamate (relative to creatine) levels were significantly higher in patients than controls in the anterior cingulate, but not occipital, cortex. Anterior cingulate glutamate/creatine levels were also correlated with intensity of social anxiety symptoms. These findings provide new evidence of glutamate's involvement in the neural mechanism underlying social phobia.