Full Spectrum of Psychiatric Disorders Related to Foreign Migration A Danish Population-Based Cohort Study

Importance: Although increased risk for schizophrenia among immigrants is well established, knowledge of the broader spectrum of psychiatric disorders associated with a foreign migration background is lacking. Objective: To examine the full range of psychiatric disorders associated with any type of foreign migration background among persons residing in Denmark, including foreign-born adoptees, first- and second-generation immigrants, native Danes with a history of foreign residence, and persons born abroad to Danish expatriates. Design and Setting: Danish population-based cohort study. Persons were followed up from their 10th birthday for the development of mental disorders based on outpatient and inpatient data. Participants: All persons born between January 1, 1971, and December 31, 2000 (N= 1 859 419) residing in Denmark by their 10th birthday with follow-up data to December 31, 2010. Main Outcome Measures: Incidence rate ratios (IRRs) and cumulative incidences for psychiatric outcomes. Results: All categories of foreign migration background, except persons born abroad to Danish expatriates, were associated with increased risk for at least 1 psychiatric disorder. Foreign-born adoptees had increased IRRs for all psychiatric disorders and had the highest IRRs for these disorders compared with other foreign migration categories. First-and second-generation immigrants having 2 foreign-born parents had significantly increased IRRs for schizophrenia and schizophrenia spectrum disorders and had similar risk magnitudes. Second- generation immigrants having 1 foreign-born parent had significantly increased IRRs for all psychiatric disorders. Native Danes with a history of foreign residence had increased IRRs for bipolar affective disorder, affective disorders, personality disorders, and schizophrenia spectrum disorders. Conclusions and Relevance: The extent to which a background of foreign migration confers an increased risk for the broad spectrum of psychiatric disorders varies according to parental origin, with greatest risks for foreign-born adoptees. The spectrum of psychiatric disorders showed greater variation within the second-generation immigrant group than between first-generation vs second-generation immigrants, and the spectrum differed according to whether individuals had 1 or 2 foreign-born parents.