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Title: Investigating the potential cognitive-behavioural mechanism of change underlying abstinence from cannabis use amongst young people with a history of psychosis and problematic cannabis use
Author: Sheridan Rains, Luke
ISNI:       0000 0004 8500 3576
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2019
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Cannabis use in psychosis is associated with poorer clinical and functional outcomes. To date there is little evidence of any effective treatments for this cohort. Contingency management (CM) involves reinforcing substance abstinence using rewards. CIRCLE was the first trial of CM focused on cannabis use in people with psychosis (n=551). The aim of this thesis was to conduct a process evaluation of CIRCLE and to consider how to improve treatment for this cohort. It includes five studies: 1) A systematic review of whether CM treatment is improved by combining it with another formal, evidence-based psychotherapy. 2 and 3) A process evaluation of CIRCLE. A quantitative study (n=353) tested the cognitive-behavioural mechanism of action of the CM intervention. A qualitative study (n=20) explored participants' experiences and views of the trial. 4) A quantitative study (n=353) explored participants' reasons for quitting and predictors of cannabis use status. 5) A qualitative study (n=20) explored the process of change underlying quitting in this cohort. The systematic review found no evidence that adding another psychotherapy to CM improved outcomes. In the CIRCLE process evaluation, there was no evidence of a benefit from CM. Participants reported that CM motivated them to engage with treatment but did not enough to quit. Negative use expectancies, including impact on mental health, 'self-concept', and financial concerns were participants' main reasons for wanting to quit. Frequency of urges was the most important predictor of abstinence by follow-up. Peer support was the most positively viewed form of support. There is limited evidence that CM is an effective treatment in this cohort. Reasons why psychotherapies often fail in this group are likely related to the multiple disadvantages faced by this population. Supporting people in this population may require a more complex and intensive intervention, which addresses a range of clinical and functional domains.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available