Full spectrum of psychiatric disorders related to foreign migration: a Danish population-based cohort study

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.

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.

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.

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.

Incidence rate ratios (IRRs) and cumulative incidences for psychiatric outcomes.

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.

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.