• Brain activity, assessed using functional magnetic resonance imaging (fMRI) [ Time Frame: Measured at baseline and after 3 and 12 months ] [ Designated as safety issue: No ]
  

• Social anxiety symptoms [ Time Frame: Measured at baseline and after 3, 6, and 12 months ] [ Designated as safety issue: No ]
  

Social anxiety disorder (SAD) is characterized by intense and debilitating anxiety in common social situations. Cognitive behavioral therapy (CBT) is a talking treatment that aims to reduce immediate anxiety symptoms. However, some anxiety symptoms and comorbid disorders not directly addressed by CBT may only improve in the short term, while recurring in the long term. Behavioral therapy based on acceptance and mindfulness is thought to have longer lasting effects, because this approach emphasizes accepting anxiety instead of controlling anxiety. This study will compare standard CBT to acceptance and commitment therapy (ACT), which uses acceptance and mindfulness, to determine which is more effective on both a short- and long-term basis.

Participants with SAD will undergo brain scans to determine how the two therapies affect brain functioning.

Participation in this study will last 12 months. Participants with SAD will be randomly assigned to receive CBT, ACT, or a waitlist condition. Both CBT and ACT treatments will include 12 weekly sessions that will deal with objects and situations that provoke anxiety. All sessions will be audio- and videotaped. The waitlist group will complete weekly self-monitoring forms to track anxiety and panic and will receive a phone call from a research coordinator every 2 weeks to make sure symptoms have not worsened. After 12 weeks, participants on the waitlist will be offered treatment.

All participants will attend study visits to undergo brain scanning at baseline, after 3 months, and after 12 months. Each study visit will involve MRI scanning (to evaluate brain structure), functional MRI (fMRI) scanning (to evaluate brain function), questionnaires about a participant's experience in the scanner, and collection of saliva samples before, during, and after scanning. While undergoing the fMRI scan, participants will be asked to remain at rest for a certain period of time, and then to perform tasks that will engage certain parts of the brain. Assessments for all participants will occur at baseline and after 3, 6, and 12 months. These assessments will include diagnostic evaluations by a therapist, self-report questionnaires, ongoing self-monitoring, physiological measurements, cognitive assessments, and behavioral observation.