Introduction

In the 1930s, Ödegaard (1932) reported that first-admission rates for schizophrenia were high among Norwegian migrants to the United States. Since then numerous studies in a variety of countries have investigated rates of serious mental illness in migrant groups and in different cultural and ethnic groups within countries (Cantor-Graae and Selten, 2005). In this chapter, we review the literature reporting differences in the incidence of psychosis between migrant and ethnic groups, we discuss methodological issues and, using the best-researched group, people of African and Caribbean origin in the UK, we try to build a model of how migration, culture and ethnicity affect rates of incident psychosis.

History and overview

Since high rates of mental illness among Norwegian migrants to the United States were reported in the first half of the last century (Ödegaard, 1932) there have been a number of studies investigating the incidence of psychosis in migrant and ethnic minority groups. Although the vast majority of migration is between developing countries within Africa and Asia, there is surprisingly little research on the risk of psychosis in these groups. Research into the incidence of psychosis in migrant groups is best developed in northern Europe. The most comprehensive literature on the subject concerns the high incidence of schizophrenia in people of African and Caribbean origin who migrated to the UK, mainly in the 1940s and 1950s, and in their children and grandchildren, a finding which has been consistently reported for 30 years.