Do risk factors for schizophrenia predispose to emigration?

Carsten Bocker Pedersen, Preben Bo Mortensen, Elizabeth Cantor-Graae

Research output: Contribution to journalArticlepeer-review

14 Citations (SciVal)

Abstract

Objective: Increased incidence rates of schizophrenia in immigrants still lack a satisfactory explanation. The aim of this study was to examine the hypothesis that risk factors for schizophrenia also increase the risk of emigration to a foreign country. If valid, Danes emigrating from Denmark carry a higher predisposition to develop schizophrenia compared to Danes living in Denmark. Methods: Utilizing data from the Danish Civil Registration System, we established a population-based cohort of 1.10 million native Danes. We assessed relative risks of emigration to a foreign country in relation to sex, age, urban birth, parental age, and a history of mental illness. Results: Urban birth in Denmark was a significant predictor of emigration to a foreign country. A maternal history of psychiatric contact during childhood and a parental history of bipolar affective disorder increased the risks of emigration. A personal history of mental illness decreased the risk of emigration, mostly for people diagnosed with schizophrenia. Conclusions: Our study provided evidence that Danish emigrants residing in a foreign country have both a higher predisposition of schizophrenia due to differential exposure to birth in urban areas and a lower predisposition of schizophrenia due to differential exposure to a history of mental illness. Although competing selection mechanisms operate, the combined effect of these different selection mechanisms was limited, thus suggesting a potential role for yet to be identified adverse environmental effects operating either before or after emigration. (C) 2011 Elsevier B.V. All rights reserved.
Original languageEnglish
Pages (from-to)229-234
JournalSchizophrenia Research
Volume127
Issue number1-3
DOIs
Publication statusPublished - 2011

Subject classification (UKÄ)

  • Psychiatry

Keywords

  • Schizophrenia
  • Bipolar affective disorder
  • Emigration
  • Denmark
  • Epidemiology
  • Risk factor

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