An investigation of response to different treatment modalities in Cognitive Behavioural Therapy for Obsessive Compulsive Disorder

Student thesis: Doctoral ThesisPhD


Background: Obsessive Compulsive Disorder (OCD) is a relatively common mental health problem that is known to be particularly disabling. Cognitive Behavioural Therapy (CBT), which inevitably includes Exposure and Response Prevention (ERP) is effective and is the first line (and only evidence-based) psychological treatment for OCD. However, a large proportion of service users do not respond optimally to CBT in both the short and long term. The National Institute for Health and Care Excellence (NICE) recommends that an intensive version of treatment be made available to those who have not responded to two or more courses of CBT. Research on the reasons for such treatment failure has predominantly been investigated from the perspective of clinical services and the rationale for recommending intensive treatment is weak. Little is known about service users or therapists’ views on reasons for treatment failure and the recommended alternative therapy formats in CBT, or on how widely intensive treatment is utilised, or even the current state of the evidence-base for this format. The aim of the current thesis is to gain a deeper understanding of each of these areas. Method: A wide variety of methods are used to gain a rounded understanding. Study 1 comprised a systematic review to assess the current evidence for the use of intensive CBT for OCD. Study 2 utilised a mixed methods design to investigate the experience of treatment failure from the perspective of the service user. Participants with OCD (n = 6) and Panic Disorder (n = 6) who had previously experienced > 2 unsuccessful courses of CBT were recruited. Study 3 utilised qualitative methodology to explore participants’ views on the experience of or prospect of undertaking CBT in an intensive format. Participants with OCD (N = 30) who had previously experienced > 2 unsuccessful courses of CBT took part. Study 4 employed mixed methods to investigate psychological therapists’ (N = 132) attitudes towards delivering intensive CBT and their utilisation of this format in their clinical practice. Study 5 utilised a quantitative approach to investigate participants with OCD (N = 235) preference for treatment format from both a practical and therapeutic perspective. Study 6 utilised qualitative methodology to explore the experience of relapse from the perspective of the service user. Participants with OCD (N = 27) had previously experienced > 2 unsuccessful courses of CBT, followed by a successful course of CBT after which they experienced a relapse in their OCD. Results: Study 1 identified four Randomised Controlled Trials (RCTs) providing evidence of promise for efficacy of this format. However, further high quality RCTs are required for a meta-analysis from which more definitive conclusions can be drawn. Study 2 revealed that participants mainly attributed therapy failure to the therapeutic interaction. Most reasons identified were pertinent to both participants with OCD and PD suggesting that such factors are specific to CBT rather than OCD. In Study 3 intensive CBT was perceived by participants as acceptable and facilitated aspects of CBT that a weekly format was unable to. Participants also reported reservations about the intensity of the format. In Study 4 therapists perceived intensive CBT to be equally or more effective than standard CBT, although barriers to its use in clinical practice were identified. Study 5 revealed that participants with greater functional impairment and an experience of CBT failure or intensive CBT showed a greater preference for an intensive format. In Study 6 a combination of life stressors, cognitive and behavioural patterns and a lack of follow-up after CBT were identified as contributors to relapse. Conclusions: The results of this research provide support from patients and therapists for the NICE recommendation of an intensive version of CBT for those whom treatment in a weekly format has been unsuccessful. However, it is unlikely to be widely available and there may be scope for hybridisation. Further research is required to address the provision of follow-up after the completion of CBT. The clinical implications of the findings are discussed along with study limitations. Further directions for future research are proposed.
Date of Award24 Jun 2020
Original languageEnglish
Awarding Institution
  • University of Bath
SupervisorSarah Halligan (Supervisor), Paul Salkovskis (Supervisor) & James Gregory (Supervisor)


  • OCD
  • CBT
  • Intensive CBT

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