Cognitive behavioral therapy (CBT) is a type of psychotherapy that can alleviate symptoms in people with social anxiety disorder, but researchers don't know exactly how it works.
Now new evidence published in Translational Psychiatry in February 2016 suggests that CBT may relieve anxiety by not only reducing the activity that takes place within the amygdala—a part of the brain linked to fear—but by actually changing the physical structure of it.
Researchers randomly assigned 26 people with social anxiety disorder to CBT or a control treatment, an attention-training method known as attention bias modification. Both treatments were provided over the Internet. CBT lasted for nine weeks, while attention bias modification was completed in four weeks.
Researchers used magnetic resonance imaging (MRI) to measure changes in the amygdala and its activity in response to criticism, both before and nine weeks after treatment, in all participants. The researchers also measured participants’ symptoms of social anxiety disorder before and after treatment.
Overall, CBT reduced anxiety more effectively than attention bias modification. On brain imaging, successful CBT resulted in reduced gray matter volume and activity in both the left and right amygdala. Knowing what changes effective treatment produces may help researchers to develop better therapies for people with anxiety.