Cognitive Behavioural Therapy for treatment resistant depression in primary care (COBALT)

The COBALT Study: Cognitive Behavioural Therapy as an adjunct to pharmacotherapy for treatment resistant depression in Primary Care: a randomised controlled trial.


Antidepressants are often the first line treatment for depression but only about one third of patients respond fully to pharmacotherapy. COBALT is a pragmatic randomised controlled trial which aims to examine the clinical and cost effectiveness of Cognitive Behavioural Therapy (CBT) given in addition to antidepressants for patients with treatment resistant depression in Primary Care. The study is a multi-centre trial in collaboration with the Universities of Bristol and Glasgow with the work being undertaken locally between the Peninsula Medical School and the Mood Disorders Centre (University of Exeter). Patients who have taken antidepressants for at least 6 weeks but who continue to have significant symptoms will be eligible to take part and we aim to recruit 160 patients locally through GP practices throughout Devon. Consenting patients will be randomised to a) Usual care: antidepressant medication and clinical management or b) CBT: 12–18 sessions of CBT in addition to antidepressant medication. Outcomes will be measured at 6 months and 12 months post-randomisation. The primary outcome is the Beck Depression Inventory (BDI) score at 6-months, with a threshold of 50% improvement in symptoms indicating a response. Secondary outcomes include remission of symptoms, quality of life and use of antidepressants. Cost-effectiveness of the CBT intervention will also be assessed. COBALT is funded by the NHS Health Technology Assessment Programme (NCCHTA).

Participant recruitment commenced in November 2008.

Paper recently published:

Simmonds B, Turner N, Thomas L, Campbell J, Lewis G, Wiles N, Turner K. Patients' experiences of participating in a large-scale trial of cognitive behavioural therapy for depression: a  mixed methods study. Family Practice Advance Access, published 12 July 2013. doi:10.1093/fampra/cm1028

Wiles NJ, Thomas L, Turner N, Garfield K, Kounali D, Campbell J, Kessler D, Kuyken W, Lewis G, Morrison J, Williams C, Peters TJ, Hollinghurst S. Long-term effectiveness and cost-effectiveness of cognitive behavioural therapy as an adjunct to pharmacotherapy for treatment-resistant depression in primary care: follow-up of the CoBalT randomised controlled trial. Lancet Psychiatry 2016 doi: 10.1016/S2215-0366(15)00495-2 Pubmed


Core staff

Professor John Campbell, Professor of General Practice & Primary Care, Co-Principal Investigator
Professor Willem KuykenMood Disorders Centre, Co-Principal Investigator

Ms Rachel Winder, Research Fellow
Mrs Anna Abel, Research Fellow
Dr Caroline Jenkinson, Associate Research Fellow
Holly Sugg – Research Administrator


UEMS (Primary Care)
Smeall Building
St Luke's Campus
Tel: 01392 722741
Fax: 01392 432223

The Mood Disorders Centre
School of Psychology
Washington Singer Laboratories
University of Exeter
Perry Road
Exeter EX4 4QG
Tel: 01392 723493
Fax: 01392 724623