Use of illicit substances in a psychosis incidence cohort: a comparison among different ethnic groups in the Netherlands

Objective: Use of illicit substances has been suggested as an explanation for the increased incidence of psychosis among some immigrant groups. The aim of the present study is to compare the rates of illicit substance use among immigrants with a first psychosis with that among non-migrants. Method: A population-based, first-contact incidence study in the Netherlands. Patients and key informants were interviewed about drug use in the preceding year. Results: One hundred and eighty-one subjects were examined. Proportions of patients who misused any illicit substance were 23% for Dutch, 17% for Moroccans, 27% for Surinamese, 30% for Turkish subjects, and 33% for other immigrants. Logistic regression analysis, controlling for age and sex, showed that ethnicity did not significantly contribute to the prediction of substance misuse. Conclusion: A higher rate of drug misuse is an unlikely explanation for the increased incidence of psychotic disorders among Moroccan and Surinamese immigrants to the Netherlands.