Illicit substance use and its correlates in first episode psychosis

Objective: To determine if substance use (particularly cannabis) is more frequent among first episode psychosis patients and associated with a more problematic clinical presentation. Method: All first episode psychosis (FEP) patients presenting to secondary services were recruited from London and Nottingham, over 2 years, in the Aetiology and Ethnicity of Schizophrenia and Other Psychoses study broad framework. Clinical and sociodemographic variables were assessed using a set of standardized instruments. A schedule was created to retrospectively collate substance use data from patients, relatives and clinicians. Results: Five hundred and eleven FEP were identified. They used three to five times more substances than general population. Substance use was associated with poorer social adjustment and a more acute mode of onset. Cannabis use did not affect social adjustment, but was associated with a more acute mode of onset. Conclusion: Cannabis has a different impact on FEP than other substances. Large epidemiological studies are needed to disentangle cannabis effect.