Posted by Michael Bell on November 22, 2008, at 19:13:53
Add this to the list of abnormal brain/neurotransmitter functions in social phobia. Here are two studies depicting glutamate abnormalities:
Study 1:
OBJECTIVE: Abnormalities in brain gamma-aminobutyric acid (GABA) and glutamate may be relevant to the underlying pathophysiology of anxiety disorders including social anxiety disorder (SAD). METHODS: We used proton magnetic resonance spectroscopy (pMRS) to examine whole brain and regional GABA, glutamate and glutamine in patients (N=10) with SAD at baseline compared to a matched group of healthy controls (HC), and changes following 8 weeks of pharmacotherapy with levetiracetam. RESULTS: For SAD subjects, there were significantly higher whole brain levels of glutamate and glutamine, though no significant differences in GABA. In the thalamus, glutamine was higher and GABA lower for SAD subjects. There was a significant reduction in thalamic glutamine with levetiracetam treatment. CONCLUSION: Our findings provide preliminary support for impaired GABAergic and overactive glutamatergic function in social anxiety disorder and the potential relevance of changes in these systems for the anxiolytic response to levetiracetam.
Study 2: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.
poster:Michael Bell
thread:864755
URL: http://www.dr-bob.org/babble/20081114/msgs/864755.html