PURPOSE The primary purpose is to enhance our understanding of the mechanisms essential in effective treatment of panic disorder.

METHODS Design: The present study has a between-subjects design, including a waiting group of participants with panic symptoms and a treatment group of participants with panic symptoms who will receive cognitive-behavioural treatment before being tested.

Participants: Twenty-eight volunteers with panic symptoms will be recruited. For participants who do meet the basic study criteria a phone screening appointment (10 - 30 mins) will be arranged to further screen for relevant inclusion and exclusion criteria. They will then be invited to the Department of Psychiatry for the pre-assessment session.

Treatment: Within the study, the investigators will offer participants a brief CBT course of 4 sessions, offered by the Lupina service. The Lupina Service forms part of the OBMH primary care Counselling \& Psychology Service, based at the Warneford Hospital. It provides intensive individual CBT for panic disorder and agoraphobia and is staffed by trained graduate volunteer therapists. Potential therapists are psychology graduates with prior mental health experience, who are given 2 days' intensive training in CBT for panic disorder and agoraphobia by Alison Croft, Consultant Clinical Psychologist. They then receive group supervision of their clinical cases. Service evaluation indicates equivalent clinical outcomes for volunteer therapists relative to qualified clinical psychologists.

Procedure: Participants will be randomly allocated to either the treatment group or the waiting group. On arrival to the pre-assessment session, participants will be given a copy of the information sheet (previously seen during the online screening and e-mailed/ posted to them). They will be invited to fill out the consent form. Screening for past or previous psychiatric illness will be achieved using a structured clinical interview (SCID). In addition, participants will be asked to complete a battery of questionnaires. They will also be familiarised with the procedure occurring on the scanning day. Any outstanding questions the participant has will be addressed. The visit lasts about 1 to 1 ½ hrs. After the pre-assessment, a 4 weeks follow-up appointment (post-assessment) will be arranged with all participants. Half of the participants will be referred for treatment in the LUPINA group during that time. At the post-assessment 4 weeks later, the participants will be asked to come to the OCMR (Oxford Clinical Resonance Imaging) Department at the John Radcliffe Hospital. The visit will last a total of 2½ to 3 hrs and include a scanning session lasting 1 to 1 ½ hrs. Subjective mood will be assessed on the day of the scan using the State form of the State-Trait Anxiety Inventory, a Mood Visual Analogue Scale and the Positive and Negative Affect Schedule. In addition, subjects will again complete the questionnaires from the pre-assessment. After the scan, participants will work on two behavioural computer tasks using emotional faces and word stimuli to assess facial recognition and attention outside the scanner. At the end of the session, patients from the waiting group will be offered the taster-CBT treatment within the LUPINA service.