An elevated risk for psychoses—psychiatric disorders such as schizophrenia that are characterized by a disconnect from reality—have been observed among migrant groups since 1932, when Norwegians moving to the United States displayed higher rates, according to background information in the article. "Immigration is an important life event and difficulties in assimilation may remain chronic as conceptualized within the stress-vulnerability model of risk for psychosis, although individual risk is still considered to be mediated through genetic susceptibility," the authors write.

Jeremy W. Coid, M.D., of St. Bartholomew's Hospital, London, and colleagues studied 484 patients in three inner-city boroughs of East London who first developed psychoses between 1996 and 2000. The patients, age 18 to 64, provided information about their self-described ethnicity, place of birth, and the place where their parents were born. Participants fell into six ethnic subgroups: white British, white other (including Irish and European), black Caribbean, black African, Asian (including Indian, Pakistani and Bangladeshi group) and all other groups (including Chinese, other Asian and those of mixed ethnicity).

"Raised incidence of both non-affective [not related to emotion or mood] and affective psychoses were found for all of the black and minority ethnic subgroups compared with white British individuals," the authors write. "The risk of non-affective psychoses for first and second generations varied by ethnicity." For example, black Caribbean second-generation immigrants were at higher risk for psychoses than their first-generation counterparts. Asian women of both generations, but not men, also had an increased risk compared with white British individuals.

The differences in psychosis rates between generations for some ethnic groups was likely due to age, the authors note. "The black Caribbean group provides an illustration of this: first- and second-generation immigrants were both at significantly greater risk for non-affective psychoses than the white British group, but the magnitude of this risk was significantly greater in the second generation; this is principally because first-generation black Caribbean immigrants have now largely passed through the main period of risk of psychoses," they write.

Several main factors associated with immigration may also be associated with psychoses, including discrimination, isolation and alienation, the authors note. "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," they write. "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."

 This study was funded by grants from St. Bartholomew's Hospital and the Royal London Hospital Special Trustees and East London and the City Mental Health NHS Trust R&D.

Note: If no author is given, the source is cited instead.

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