Do risk factors for schizophrenia predispose to emigration?

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.