Neighbourhood variation in incidence of schizophrenia

Abstract

BACKGROUND: Neighbourhood characteristics may influence the risk of psychosis, independently of their individual-level equivalents. AIMS: To examine these issues in a multi-level model of schizophrenia incidence. METHOD: Cases of schizophrenia, incident between 1986 and 1997, were identified from the Maastricht Mental Health Case Register. A multi-level analysis was conducted to examine the independent effects of individual-level and neighbourhood-level variables in 35 neighbourhoods. RESULTS: Independent of individual-level single and divorced marital status, an effect of the proportion of single persons and proportion of divorced persons in a neighbourhood was apparent (per 1% increase respectively: RR = 1.02; 95% CI 1.00-1.03; and RR = 1.12, 95% CI 1.04-1.21). Single marital status interacted with the neighbourhood proportion of single persons, the effect being stronger in neighbourhoods with fewer single-person households. CONCLUSIONS: The neighbourhood environment modifies the individual risk for schizophrenia. Premorbid vulnerability resulting in single marital status may be more likely to progress to overt disease in an environment with a higher perceived level of social isolation.