"Generalized social phobia is characterized by fear/avoidance of social situations and fear of being judged negatively by others. It is the most common anxiety disorder in the general population, with the lifetime prevalence estimated at 13.3 percent, and it is associated with a high risk for depression, alcohol and drug abuse and suicide," wrote the authors.
In earlier studies, researchers found differences in the way brains of affected individuals respond to facial expressions, suggesting that the condition involves increased responsiveness to social stimuli in areas linked to emotion.
Led by Karina Blair, Ph.D., at the National Institute of Mental Health, Bethesda, Md., the researchers in the current study, compared functional MRI (fMRI) scans of 17 unmedicated individuals with generalized social phobia to those of 17 controls who were the same age and sex and had the same IQ but did not have the disorder.
"During fMRI scans, individuals read positive (e.g., You are beautiful), negative (e.g., You are ugly) and neutral (e.g., You are human) comments that could be either about the self or about somebody else (e.g., He is beautiful)," wrote the authors.
While reading negative statements about themselves, patients with generalized social phobia were found to have increased blood flow in their medial prefrontal cortex and amygdala, areas of the brain linked to concepts of self as well as fear, emotion and stress response.
But, no differences were observed between the two groups in response to negative comments referring to others or neutral or positive comments referring to either self or others.
"Given that medial prefrontal cortex regions are involved in representations of the self, it might be suggested that these regions, together with the amygdala, play a primary role in the development and maintenance of generalized social phobia and that the pathology in the disorder at least partly reflects a negative attitude toward the self, particularly in response to social stimuli-that in generalized social phobia what engages the mind is others' criticism," concluded the authors.
They added: "This highly context-dependent response in generalized social phobia helps constrain existing models of the disorder and may thus guide future therapeutic formulations in the treatment of the disorder."
The study is published in the latest issue of Archives of General Psychiatry, one of the JAMA/Archives journals.