title: Reasons for cannabis use in first-episode psychosis: does strength of endorsement change over 12 months?
abstract: BACKGROUND
  Why patients with psychosis use cannabis remains debated. The self-medication hypothesis has received some support but other evidence points towards an alleviation of dysphoria model. This study investigated the reasons for cannabis use in first-episode psychosis (FEP) and whether strength in their endorsement changed over time.
  
  
  METHODS
  FEP inpatients and outpatients at the South London and Maudsley, Oxleas and Sussex NHS Trusts UK, who used cannabis, rated their motives at baseline (n=69), 3 months (n=29) and 12 months (n=36). A random intercept model was used to test the change in strength of endorsement over the 12 months. Paired-sample t-tests assessed the differences in mean scores between the five subscales on the Reasons for Use Scale (enhancement, social motive, coping with unpleasant affect, conformity and acceptance and relief of positive symptoms and side effects), at each time-point.
  
  
  RESULTS
  Time had a significant effect on scores when controlling for reason; average scores on each subscale were higher at baseline than at 3 months and 12 months. At each time-point, patients endorsed 'enhancement' followed by 'coping with unpleasant affect' and 'social motive' more highly for their cannabis use than any other reason. 'Conformity and acceptance' followed closely. 'Relief of positive symptoms and side effects' was the least endorsed motive.
  
  
  CONCLUSIONS
  Patients endorsed their reasons for use at 3 months and 12 months less strongly than at baseline. Little support for the self-medication or alleviation of dysphoria models was found. Rather, patients rated 'enhancement' most highly for their cannabis use.
authors.affiliation: Department of Psychological Medicine, PO92, Institute of Psychiatry, King's College London, De Crespigny Park, SE5 8AF London, UK. Electronic address: anna.kolliakou@kcl.ac.uk.
authors.forename: A
authors.initials: A
authors.lastname: Kolliakou
authors.affiliation: Department of Psychiatry, University of Melbourne, Melbourne, Australia.
authors.forename: D
authors.initials: D
authors.lastname: Castle
authors.affiliation: MRC Integrative Epidemiology Unit, School of Social and Community Medicine, University of Bristol, Bristol, UK.
authors.forename: H
authors.initials: H
authors.lastname: Sallis
authors.affiliation: Department of Psychosis Studies, Institute of Psychiatry, King's College London, London, UK.
authors.forename: C
authors.initials: C
authors.lastname: Joseph
authors.affiliation: Department of Psychosis Studies, Institute of Psychiatry, King's College London, London, UK.
authors.forename: J
authors.initials: J
authors.lastname: O'Connor
authors.affiliation: Department of Psychosis Studies, Institute of Psychiatry, King's College London, London, UK.
authors.forename: B
authors.initials: B
authors.lastname: Wiffen
authors.affiliation: Department of Health Service and Population Research, Institute of Psychiatry, King's College London, London, UK.
authors.forename: C
authors.initials: C
authors.lastname: Gayer-Anderson
authors.affiliation: Department of Psychosis Studies, Institute of Psychiatry, King's College London, London, UK.
authors.forename: G
authors.initials: G
authors.lastname: McQueen
authors.affiliation: Department of Psychosis Studies, Institute of Psychiatry, King's College London, London, UK.
authors.forename: H
authors.initials: H
authors.lastname: Taylor
authors.affiliation: Department of Psychosis Studies, Institute of Psychiatry, King's College London, London, UK.
authors.forename: S
authors.initials: S
authors.lastname: Bonaccorso
authors.affiliation: Department of Psychosis Studies, Institute of Psychiatry, King's College London, London, UK.
authors.forename: F
authors.initials: F
authors.lastname: Gaughran
authors.affiliation: Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, King's College London, London, UK.
authors.forename: S
authors.initials: S
authors.lastname: Smith
authors.affiliation: School of Psychology, University of Sussex, Sussex, UK.
authors.forename: K
authors.initials: K
authors.lastname: Greenwood
authors.affiliation: Department of Psychosis Studies, Institute of Psychiatry, King's College London, London, UK.
authors.forename: R M
authors.initials: RM
authors.lastname: Murray
authors.affiliation: Department of Psychosis Studies, Institute of Psychiatry, King's College London, London, UK.
authors.forename: M
authors.initials: M
authors.lastname: Di Forti
authors.affiliation: Department of Neuroimaging, Institute of Psychiatry, King's College London, London, UK.
authors.forename: Z
authors.initials: Z
authors.lastname: Atakan
authors.affiliation: Department of Psychological Medicine, PO92, Institute of Psychiatry, King's College London, De Crespigny Park, SE5 8AF London, UK.
authors.forename: K
authors.initials: K
authors.lastname: Ismail
mesh_terms: D000223:Adaptation, Psychological; D000328:Adult; D000368:Aged; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D002189:Marijuana Abuse / Q000523:psychology*; D008385:Marijuana Smoking / Q000523:psychology*; D008875:Middle Aged; D009042:Motivation; D011618:Psychotic Disorders / Q000175:diagnosis* / Q000523:psychology*; D012919:Social Behavior
keywords: Alleviation of dysphoria; Cannabis use; Psychosis; Reasons for cannabis use; Schizophrenia; Self-medication