Skip to main content
    • Aa
    • Aa

Urbanization and risk for schizophrenia: does the effect operate before or around the time of illness onset?

  • M. MARCELIS (a1), N. TAKEI (a1) and J. VAN OS (a1)
    • Published online: 01 September 1999

Background. Higher level of urbanicity of place of birth and of place of residence at the time of illness onset has been shown to increase the risk for adult schizophrenia. However, because urban birth and urban residence are strongly correlated, no conclusions can be drawn about the timing of the risk-increasing effect. The current study discriminated between any effect of urbanization before and around the time of illness onset.

Methods. All individuals born between 1972 and 1978 were followed up through the Dutch National Psychiatric Case Register for first admission for schizophrenia until 1995 (maximum age 23 years). Exposure status was defined by a combination of place of birth and place of residence at the time of illness onset in the three most densely populated provinces of the Netherlands (the ‘Randstad’, exposed) or in all other areas (the ‘non-Randstad’, non-exposed). The risk for schizophrenia was examined in four different exposure groups: non-exposed born and non-exposed resident (NbNr, reference category), non-exposed born and exposed resident (NbEr), exposed born and non-exposed resident (EbNr) and exposed born and exposed resident (EbEr).

Results. The greatest risk for schizophrenia was found in the EbNR group, without evidence for any additive effect of urban residence (rate ratio (RR) for narrow schizophrenia in EbNr group, 2·05 (95% CI 1·18–3·57); in EbEr group, 1·96 (95% CI, 1·55–2·46)). Individuals who were not exposed at birth, but became so later in life, were not at increased risk of developing schizophrenia (RR for narrow schizophrenia in NbEr group, 0·79 (0·46–1·36)).

Conclusion. The results suggest that environmental factors associated with urbanization increase the risk for schizophrenia before rather than around the time of illness onset.

Corresponding author
Address for correspondence: Dr Jim van Os, Department of Psychiatry and Neuropsychology, European Graduate School of Neuroscience, University of Maastricht, PO Box 616, 6200 MD Maastricht, The Netherlands.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Psychological Medicine
  • ISSN: 0033-2917
  • EISSN: 1469-8978
  • URL: /core/journals/psychological-medicine
Please enter your name
Please enter a valid email address
Who would you like to send this to? *


Full text views

Total number of HTML views: 0
Total number of PDF views: 68 *
Loading metrics...

Abstract views

Total abstract views: 236 *
Loading metrics...

* Views captured on Cambridge Core between September 2016 - 21st October 2017. This data will be updated every 24 hours.