Raised Incidence Rates of All Psychoses Among Migrant Groups

CONTEXT: Certain black and minority ethnic groups are at increased risk for psychoses. It is unknown whether risk for second- and later-generation black and minority ethnic groups in the United Kingdom is universally increased or varies by ethnicity, population structure, or diagnostic category. OBJECTIVES: To examine whether excess risk in black and minority ethnic groups varies by generation status and to determine whether this is explained solely by an excess of broadly defined schizophrenia. DESIGN: Population-based epidemiological survey of first-onset psychoses during a 2-year study period. SETTING: Three inner-city boroughs in East London, England. Patients Four hundred eighty-four patients with first-episode psychosis aged 18 to 64 years. MAIN OUTCOME MEASURES: Nonaffective or affective psychoses according to the DSM-IV. RESULTS: Raised incidence of both nonaffective and affective psychoses were found for all of the black and minority ethnic subgroups compared with white British individuals. The risk of nonaffective psychoses for first and second generations varied by ethnicity (likelihood ratio test, P = .06). Only black Caribbean second-generation individuals were at significantly greater risk compared with their first-generation counterparts (incidence rate ratio, 2.2; 95% confidence interval, 1.1-4.2) corrected. No significant differences between first and second generations were observed in other ethnic groups. Asian women but not men of both generations were at increased risk for psychoses compared with white British individuals. Patterns were broadly upheld for the affective psychoses. CONCLUSIONS: Both first- and second-generation immigrants were at elevated risk for both nonaffective and affective psychoses, but this varied by ethnicity. Our results suggest that given the same age structure, the risk of psychoses in first and second generations of the same ethnicity will be roughly equal. We suggest that socioenvironmental factors operate differentially by ethnicity but not generation status, even if the exact specification of these stressors differs across generations. Research should focus on differential rates of psychoses by ethnicity rather than between generations.