Neighbourhood variation in incidence of schizophrenia - Evidence for person-environment interaction

Background Neighbourhood characteristics may influence the risk of psychosi s, independently of their individual-level equivalents. Aims To examine these issues in a multilevel model of schizophrenia inciden ce. Method Cases of schizophrenia, incident between 1986 and 1997, were identif ied from the Maastricht Mental Health Case Register. A multi-level analysis was conducted to examine the independent effects of individual-level and n eighbourhood-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 p ersons 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 st atus interacted with the neighbourhood proportion of single persons, the ef fect 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 m ay be more likely to progress to overt disease in an environment with a hig her perceived level of social isolation.