Incidence of psychotic disorders in immigrant groups to the Netherlands

Background: Previous reports on the incidence of schizophrenia in immigrant groups to The Netherlands were based on hospital data. Aims: To compare the incidence of psychotic disorders in the immigrant groups to that in natives. Method: Two-year first-contact incidence study in The Hague. Results: The risks of schizophrenia, schizophreniform or schizoaffective disorder (DSM-IV criteria) were increased for subjects born in Morocco (gender and age-adjusted relative risk=4.5; 95% C11.4-8.5), Surinam (relative risk=3.2; 1.8-5.7). The Netherlands Antilles (relative risk=2.9; 0.9-9.5) and other non-Western countries (relative risk=2.4; 1.3-4.7). This risk was also increased for Moroccans (relative risk=8.0; 2.6-24.5) and Surinamese (relative risk=5.5; 2.5-11.9) of the second generation. The risks for Turkish immigrants, first or second generation, and for immigrants from Western countries were not significantly increased. Conclusions: This study indicates that the incidence of schizophrenia is increased in several, but not all, immigrant groups to The Netherlands. It is possible that factors associated with a process of rapid westernisation precipitate schizophrenia in people who are genetically at risk. Declaration of interest: Supported by the Stanley Foundation.