To what extent may the association between immigrant status and mental illness be explained by socioeconomic factors?

Immigrants in Sweden have a higher rate of mental illness than the native Swedes. This study investigated to what extent the association between immigrant status and mental illness can be explained by a different distribution of known risk factors for impaired mental health between groups of immigrants and persons born in Sweden.

The study is based on data from the Swedish PART-study, designed to identify risk factors for, and social consequences of, mental illness. The study population consists of a random sample of 10,423 Swedish citizens, whereof 1,109 were immigrants. The data was collected in the year 2000. The immigrants were divided into three groups based on country of origin (Scandinavians born outside Sweden, Europeans born outside Scandinavia, non-Europeans). The occurrence of mental illness among immigrants and native Swedes were compared not adjusting and adjusting for indicators of socioeconomic advantage/disadvantage (education, income, labour market position, etc). Mental illness was approximated with the WHO (ten) wellbeing index scale and depressive symptoms were measured with the major depression inventory scale (MDI).

Immigrants' excess risk for low subjective wellbeing was completely accounted for by adjustment for known risk factors in all the immigrant groups. However, social-economic disadvantages could not account for the non-European immigrants' higher prevalence of depression (MDI), although the increased relative risk found in univariate analyses was substantially reduced.

The findings in this study suggest that the association between immigrant status and mental illness appears above all to be an effect of a higher prevalence of social and economic disadvantage.