Ethnicity, Psychosis and Co-Morbid Substance Use Disorders in the U.K.

Student thesis: Doctoral ThesisDoctor of Philosophy


BACKGROUND: The relationship between psychotic disorders and substance use is well established but complex. High rates of psychosis and greater risk of negative outcomes have been found in Black Caribbean and Black African groups. In addition research within the general population has shown important ethnic differences in patterns of substance use disorders (SUD). An under researched issue is the impact of SUDs on treatment and outcomes for people suffering from psychosis and whether this impact differs by ethnic group.

METHOD: This PhD study aimed to investigate the prevalence, correlates and experiences of comorbid SUDs in patients with an 8-12 year history of psychosis with special attention to Black African and Black Caribbean groups. The study comprised two phases. The first phase utilised data from the AESOP-10 follow-up study of 325 epidemiologically based White British, Black Caribbean and Black African individuals who originally presented to psychiatric services in London and Nottingham between 1997 and 2000 with a psychotic disorder. The second phase was a qualitative study that purposefully selected a sub-sample of patients from the AESOP London cohort.

AIMS AND HYPOTHESES: It was hypothesised that there would be higher rates of SUDs in Black Caribbean and lower rates in Black African ethnic groups compared to White groups and that irrespective of ethnicity comorbidity will be associated various negative factors. The second phase aimed to describe the experiences of mental illness, SUDs and treatment experiences in all ethnic groups.

RESULTS: The quantitative study found that Black African patients had a significantly lower prevalence of SUDs than White patients (Comorbid DUD: OR 0.090, CI 0.025-0.327, p=0.000; Comorbid AUD: OR 0.066, CI 0.013-0.322, p=0.001). Black Caribbean patients with drug use disorders and White British patients with alcohol use disorders were more likely to have negative outcomes however many these findings failed to reach statistical significance.

Findings from the qualitative study highlighted the use of numerous devices and mechanism in account giving. Several thematic constructions were uncovered including lay models of illness aetiology, perceptions of a causal relationship between illness experiences and substance use, perceptions of a relationship between cannabis and paranoia, perceptions of cannabis use as non-problematic and the importance of the role health services (particularly talking based therapies), family and mastery play in the treatment and recovery process.

CONCLUSIONS: Mixed method design involving large longitudinal epidemiological and qualitative studies are an appropriate way of investigating the relationship between psychosis and substance use disorders. Patients with comorbid SUDs may be more likely to have subsequent relapses and hospital admissions over the course of their illness, however the likelihood of this may differ for different ethnic groups and type of substances used. Talking based treatments which focus on lay models of aetiology, mastery of symptoms and cannabis use and involve the patients larger social networks are likely to be of benefit to this population. Further epidemiological and qualitative research into the changing patterns of substance use over a time are necessary.
Date of Award2014
Original languageEnglish
Awarding Institution
  • King's College London
SupervisorCraig Morgan (Supervisor) & Stephani Hatch (Supervisor)

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