Social anxiety disorder is one of the most common mental health problems, although a new study suggests that cognitive behavioral therapy (CBT) could help to alleviate symptoms by generating actual physiological changes in the brains of sufferers.

Also known as social phobia, social anxiety disorder is characterized by an intense fear of everyday social interactions. Previous studies have shown that those who suffer from the condition tend to display above average neural responsivity in the brain region that's associated with fear, the amygdala. As a result, these people are unusually sensitive to certain emotional stimuli, such as personal criticism.

Interestingly, a new study that appeared in the journal Translational Psychiatry has identified a link between this hypersensitivity of the amygdala and the volume of grey matter – one of the two main tissues of the central nervous system – in this part of the brain.

Using functional magnetic resonance imaging (fMRI) to scan the brains of 26 individuals diagnosed with social phobia, the researchers noted that those with the most severe symptoms tended to have a greater volume of grey matter in the left amygdala.

Participants then underwent a nine-week Internet-based CBT course, during which they had regular email correspondence with a therapist, who provided emotional guidance and exercises for patients to complete in their own time. At the end of the program, participants were psychologically assessed and also asked to self-report any changes in their condition, in order to evaluate the effect of CBT on their symptoms.

At this stage, a further round of fMRI scans revealed a reduction in grey matter in the left amygdala in those who experienced positive outcomes from their therapy. Furthermore, the greater the reduction in symptoms, the more significant was the corresponding drop in grey matter volume.

The researchers therefore conclude that neural hypersensitivity in the amygdala – which is implicated in social anxiety disorder – is at least partially mediated by grey matter volume, and that CBT has the potential to reduce this, thereby alleviating symptoms.

While these results are significant, the scale of the study is relatively small, which means further studies will have to be conducted in order to confirm the robustness of these conclusions.