Roch Cantwell

Background: Studies examining the effects of substance use in patients with schizophrenia have produced conflicting results.Aims: To examine the effects of comorbid substance use on symptoms, social functioning and service use in patients with schizophrenia.Method: Patients (n=316) with and without substance use problems from three centres participating in the Scottish Comorbidity Study were compared, using research interviews and case note review, on measures of symptoms, social functioning and service use.Results: Patients with substance use problems were younger, more likely to be male and had shorter duration of illness. They had more police contact and increased self-reported needs, but otherwise showed few differences when compared with those without such problems.Conclusions: The presence of problem substance use had only modest impact on service use, symptoms or social functioning for this group of patients with schizophrenia. This has important implications for service development to meet the perceived needs of this group.

Background: Reports suggest a high prevalence of substance misuse in psychotic disorders but few studies examine comorbidity at onset of psychosis.Aims: To identify the prevalence and pattern of substance use and misuse in first-episode psychosis, and relationships with diagnosis, mode of presentation and demographic variables.Method: Consensus diagnoses for 168 subjects presenting with first-episode psychosis were made using ICD–10 diagnostic criteria. Information on substance use and misuse was obtained from multiple sources. We examined associations between substance misuse, diagnosis and demographic factors.Results: Criteria for drug use, drug misuse or alcohol misuse were met by 37% of the sample. One-year prevalence rates were 19.5% (drug misuse) and 11.7% (alcohol misuse). Thirteen subjects (8.4%) received a primary diagnosis of substance-related psychotic disorder; a significant increase compared with an earlier cohort from the same catchment area. Drug misuse was associated with younger age of onset of psychosis, male gender and non–African–Caribbean ethnicity.Conclusions: This study confirms high rates of substance misuse at onset of psychosis. There is evidence for an increase in diagnosis of substance-related psychotic disorders over time. Those most at risk of substance misuse are young males.