Neighborhood ethnic density and psychotic disorders among ethnic minority groups in Utrecht City

Recent studies have shown increased incidence of non-affective psychotic disorders (NAPD) among ethnic minorities compared to the native population, but not, or less so, in areas with a high own-group proportion. The aim is to investigate this ethnic density effect in Utrecht and whether this effect is due to higher rates of NAPD among Dutch persons in areas with high minority proportions. We also explore the geographical scale at which this effect occurs and the influence of social drift prior to NAPD. NAPD cases in the Psychiatric Case Registry Middle Netherlands (N = 2,064) and living in Utrecht during 2000-2009 were analyzed in a Poisson model in relation to both individual-level and district- vs. neighborhood-level characteristics. With increasing minority density, especially of the neighborhood, the rate ratios of NAPD significantly decreased among both non-Western (from 2.36 to 1.24) and Western immigrants (from 1.63 to 1.01), in comparison with Dutch persons. This was partly explained by higher rates of NAPD among Dutch persons in areas with high minority density. But there was also a trend to lower NAPD rates among non-Western minorities in these areas (P = 0.074).This trend was significant among Surinamese/Antilleans (P = 0.001) and Moroccans aged 18-30 years (P = 0.046). Among the Dutch, a social drift to minority-dense neighborhoods prior to NAPD registration was found. Our findings support the beneficial association with own-group presence at the smaller scale neighborhood level. Findings show also that this association is more pronounced in immigrant vs. native comparisons and is not found within all ethnic groups.