Risk of schizophrenia in second-generation immigrants: a Danish population-based cohort study

Psychol Med. 2007 Apr;37(4):485-94. doi: 10.1017/S0033291706009652. Epub 2007 Jan 4.


Background: Urban birth, a risk factor for schizophrenia, is more frequent among second-generation immigrants. The aim of the current study was to determine whether the increased risk for schizophrenia found in second-generation immigrants is explained by the degree of urbanization of birthplace and/or factors related to parentage, such as geographic origin or history of residence abroad during upbringing.

Method: Using data from the Danish Civil Registration System (CRS), we established a population-based cohort of 2.0 million Danes (persons born in Denmark). Schizophrenia in cohort members was identified by cross-linkage with the Danish Psychiatric Central Register.

Results: The relative risk of developing schizophrenia was 1.93 [95% confidence interval (CI) 1.79-2.08] and 2.96 (95% CI 2.49-3.51) among persons with one or both parents foreign-born respectively compared to native Danes. Adjustment for urbanization of birthplace and parental characteristics reduced these risks slightly. However, urbanization had a lesser effect in second-generation immigrants than in Danes. History of residence abroad was a risk factor for schizophrenia, regardless of whether parents were foreign-born or native Danes.

Conclusion: The increased risk found in second-generation immigrants cannot be explained by urbanization or parental characteristics pertaining to age, mental illness, geographic origin or residence abroad during a child's upbringing.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cohort Studies
  • Denmark / epidemiology
  • Emigration and Immigration / statistics & numerical data*
  • Female
  • Humans
  • Male
  • Population Surveillance / methods
  • Risk Factors
  • Schizophrenia / ethnology*
  • Schizophrenia / genetics*
  • Urban Population / statistics & numerical data