Incidentie van psychotische stoornissen bij immigranten hangt samen met etnische dichtheid van wijken*

Objective

To investigate if the increased incidence of psychotic disorders among immigrants depends upon the density of their own ethnic group in the neighbourhoods in which they live.

Design

Descriptive.

Method

All citizens of The Hague, the Netherlands (aged 15-54) of Dutch or Moroccan, Surinam or Turkish origin who in the years 1997-2005 made contact with a physician for a suspected psychotic disorder were identified. Semi-structured interviews were held with these individuals after which DSM IV diagnoses were assigned. The ethnic density of the neighbourhood of residence was measured as the proportion of an individual’s own ethnic group in the neighbourhood. Multi-level Poisson regression analyses were used to assess the effect of ethnic density on the incidence of psychotic disorders by calculating incidence rate ratios for each immigrant group separately, with the native Dutch population as a reference. The analyses were also performed separately for neighbourhoods with high and low ethnic densities.

Results

226 native Dutch and 240 first and second generation immigrants developed a psychotic disorder for the first time. Compared with native Dutch, the incidence rate ratios for immigrants were 2.36 (95% CI: 1.89-2.95) in neighbourhoods with a low ethnic density and 1.25 (0.66-2.37) in neighbourhoods with a high ethnic density. There was a strong interaction between individual ethnicity and neighbourhood ethnic density as predictors of incidence of psychotic disorders (adjusted χ² = 15.04; df = 1; p = 0.0001).

Conclusion

The incidence of psychotic disorders was increased most significantly among immigrants living in neighbourhoods where their own ethnic group comprised a small proportion of the population.