There is significant and independent variation of incidence of schizophrenia and other psychoses in terms of sex, age, ethnicity, and place. This confirms that environmental effects at the individual, and perhaps neighborhood level, may interact together and with genetic factors in the etiology of psychosis.

Background. The incidence of schizophrenia in the African-Caribbean population in England is reported to be raised. We sought to clarify whether (a) the rates of other psychotic disorders are increased, (b) whether psychosis is increased in other ethnic minority groups, and (c) whether particular age or gender groups are especially at risk.

An increasing number of studies are demonstrating an association between childhood abuse and psychosis. However, the majority of these rely on retrospective self-reports in adulthood that may be unduly influenced by current psychopathology. We therefore set out to explore the reliability and comparability of first-presentation psychosis patients' reports of childhood abuse. Psychosis case subjects were drawn from the Aetiology and Ethnicity of Schizophrenia and Other Psychoses (ÆSOP) epidemiological study and completed the Childhood Experience of Care and Abuse Questionnaire to elicit abusive experiences that occurred prior to 16 years of age. High levels of concurrent validity were demonstrated with the Parental Bonding Instrument (antipathy: r(s)=0.350-0.737, P<.001; neglect: r(s)=0.688-0.715, P<.001), and good convergent validity was shown with clinical case notes (sexual abuse: κ=0.526, P<.001; physical abuse: κ=0.394, P<.001). Psychosis patients' reports were also reasonably stable over a 7-year period (sexual abuse: κ=0.590, P<.01; physical abuse: κ=0.634, P<.001; antipathy: κ=0.492, P<.01; neglect: κ=0.432, P<.05). Additionally, their reports of childhood abuse were not associated with current severity of psychotic symptoms (sexual abuse: U=1768.5, P=.998; physical abuse: U=2167.5, P=.815; antipathy: U=2216.5, P=.988; neglect: U=1906.0, P=.835) or depressed mood (sexual abuse: χ(2)=0.634, P=.277; physical abuse: χ(2)=0.159, P=.419; antipathy: χ(2)=0.868, P=.229; neglect: χ(2)=0.639, P=.274). These findings provide justification for the use in future studies of retrospective reports of childhood abuse obtained from individuals with psychotic disorders.

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There is consistent and strong evidence that the incidence of all psychoses is higher in many migrant and minority ethnic populations in a number of countries. The reasons for this are, however, unclear and a wide range of explanations have been proposed, from genetic to neurodevelopmental to psychosocial. In this article, we describe and evaluate the available evidence for and against each of these. What this shows is that: (1) there are few studies that have directly investigated specific risk factors in migrant and minority ethnic populations, with often only 1 or 2 studies of any relevance to specific explanations and (2) what limited research there has been tends to implicate a diverse range of social factors (including childhood separation from parents, discrimination and, at an area level, ethnic density) as being of potential importance. In an attempt to synthesize these disparate findings and provide a basis for future research, we go on to propose an integrated model--of a sociodevelopmental pathway to psychosis--to account for the reported high rates in migrant and minority ethnic populations. Aspects of this model will be directly tested in a new Europe-wide incidence and case-control study that we will conduct over the next 3 years, as part of the European Network of National Schizophrenia Networks studying Gene-Environment Interactions programme.