Social disorganization of neighborhoods and incidence of psychotic disorders: a 7-year first-contact incidence study

Background. Environmental factors such as urban birth and ethnic minority position have been related to risk for psychotic disorders. There is some evidence that not only individual, but also neighborhood characteristics influence this risk. The aim of this study was to investigate social disorganization of neighborhoods and incidence of psychotic disorders. Method. The research was a 7-year first-contact incidence study of psychotic disorders in The Hague. Neighborhood characteristics included continuous, dichotomous and cumulative measures of socio-economic level, residential mobility, ethnic diversity, proportion of single person households, voter turnout, population density and crime level. Using multi-level Poisson regression analysis, incidence rate ratios (IRRs) and 95% confidence intervals (CIs) of psychotic disorders were calculated for the indicators of neighborhood social disorganization. Results. A total of 618 incident cases were identified. Neighborhood socio-economic level and residential mobility had the strongest association with incidence of psychotic disorders [individual-level adjusted Wald chi(2)(1) = 13.03 (p = 0.0003) and 5.51 (p = 0.02), respectively]. All but one (proportion of single person households) of the dichotomous neighborhood indicators were significantly associated with a higher IRR. The cumulative degree of neighborhood social disorganization was strongly and linearly associated with the incidence of psychotic disorders (trend test, Wald chi(2)(5) = 25.76, p = 0.0001). The IRR in neighborhoods with the highest degree of social disorganization was 1.95 (95% CI 1.38-2.75) compared with the lowest disorganization category. Conclusions. The findings suggest that the risk for developing a psychotic disorder is higher for people living in socially disorganized environments. Longitudinal studies are needed to investigate causality.