There has been a constant human migration over the centuries but this increased greatly after the middle of the 20th century. Geopolitical problems and economic disparities are cited as the major factors for this increase, which has been facilitated by improved means of travel. Countries in the West have been popular destinations, as they offer economic opportunities and safety from political strife. In European countries, ethnic minority groups are largely representative of historical colonial links, while in the USA and Canada migrants from South America and later generations of African slaves form the majority of minority ethnic groups.

Defining ethnic minorities

The concept of ethnicity is multidimensional, and includes aspects such as race, origin or ancestry, identity, language and religion. It may also include more subtle dimensions, such as culture, the arts, customs and beliefs, and even practices such as dress and food preparation. It is also dynamic and in a constant state of flux. It will change as a result of new immigration flows, blending and intermarriage, and new identities may be formed (Statistics Canada, 2008).

Rates of mental illness

Circumstances of migration and the status of being in a minority in the host country invariably put the individual under stress. The prevalence of psychiatric disorders is higher in ethnic minorities than in host populations. But this follows some peculiar trends, specific to certain ethnic groups. The incidence of schizophrenia has been found to be higher in African– Caribbean minority groups settled in the West (Selten & Sijben, 1994; Bhugra et al, 1997; Selten et al, 2007) but lower in Caribbean islands (Mahy et al, 1999). This higher prevalence persists in the second generations of African–Caribbean groups residing in the West (Bhugra & Bhui, 1998).

Ödegaard (1932) reported that migrant Norwegians in the USA had higher rates of schizophrenia than the host population, with a peak occurring 10–12 years after migration. Several later studies have similarly shown that rates of schizophrenia are higher among migrant groups than among native populations (Cooper, 2005). Cochrane & Bal (1989) observed that migrants had higher rates of admission than the native population. Similar high rates of schizophrenia have also been reported among migrant populations in The Netherlands (Selten & Sijben, 1994).