Raised rates of psychoses have been reported in immigrant groups since the 1930s and a recent analysis of over 40 studies found that the incidence of schizophrenia was, on average, nearly three times as high among immigrants than in the rest of the population. In the UK Black Caribbean and Black African groups have consistently been observed to have a higher rate of psychoses than other groups with conservative estimates suggesting a rate four to six times greater than the rest of the population. A study of 484 people suffering from psychosis in East London found that, even after socioeconomic status was taken into account, certain ethnic groups remained at more risk of developing psychoses. Black Caribbean were 3.1x more likely to develop psychosis, Black African 2.6x, Pakistani women 3.1x and Bangladeshi women 2.3x.
Kirkbride, J.B. ... [et al] - Psychoses, ethnicity and socio-economic status British Journal of Psychiatry July 2008, 193, 18-24