4 - Urbanization, migration and risk of schizophrenia

Summary

Influence of urban life

Historical context

A number of early studies (reviewed by Freeman, 1994) have shown that the rates of schizophrenia are increased in inner city areas in Western societies. One of the first papers to demonstrate this clearly was the classic monograph of Faris and Dunham (1939), who showed that first admission rates of schizophrenia were particularly high in certain areas of inner city Chicago and then decreased again towards the periphery of the city. There were considerable differences within the inner city area itself: rates were higher in the disorganized ‘hobohemia’ area than in the more cohesive working class and ethnic minority areas. The authors suggested that characteristics of certain neighbourhoods, such as social isolation and lack of cohesion, may be responsible for the increased rates of schizophrenia. Interestingly, in contrast to schizophrenia, the incidence of manic depression was not higher in the inner city, a finding that has recently been replicated by Mortensen et al. (1999).

Sadly, the refinements of Faris and Dunham's study and their discussion of possible causes of the increased rates of schizophrenia were largely ignored for many years. During the latter half of the 20th century, the generally accepted view was that the high rates of schizophrenia in the inner city could be accounted for by the tendency of people with schizophrenia, or with incipient schizophrenia, to move into the more urbanized and deprived areas. This was known as the ‘social drift’ hypothesis.