New study finds brains behind social phobia

New research common condition known as social phobia, in which individuals show a heightened response to threatening faces, or perceive normal social situations as threatening, is associated with heightened activity of the brain's 'fear centre', the amygdala.

Monash University psychologists and their overseas collaborators used functional magnetic resonance imaging (fMRI) to show that when volunteers with generalised social phobia are presented with images depicting threatening, angry, disgusted or fearful faces.

Prof Pradeep Nathan, of Monash University's Centre for Brain and Behaviour, and the Department of Physiology, led the Australian arm of the study.

In a paper to be published soon in the research journal Biological Psychiatry, Nathan and his colleagues will report that the amygdala, a small, almond-shaped structure that forms part of the limbic system is hyperactivated in social situations that subjects perceive as a potential or actual threat.

Nathan said the degree of activation is highly correlated with the severity of the patient's social phobia.

At any time, around a million Australians are suffering from social phobia, making it the third most common psychiatric disorder after depression and alcoholism, he said.

Social phobics suffer heightened anxiety during threatening social situations; they tend to avoid eye contact with others, and fear most interpersonal situations.

The brain's limbic system controls emotions, and via the sympathetic nervous system, affects heart and breathing rates, which rise in frightening situations.

According to Nathan, the study suggests fMRI can be used to monitor activity in the amygdala, and predict the level of clinical symptoms in patients with generalised social phobia -- as well as to monitor the efficacy of psychological or drug-based therapy.

Dr Luan Phan and Dr Daniel Fitzgerald, from the University of Chicago, and Dr Manuel Tancer from Wayne State University, were lead authors on the research paper.