Life events and psychosis: case-control study from India, Nigeria, and Trinidad and Tobago

BACKGROUND: There is evidence of an association between life events and psychosis in Europe, North America and Australasia, but few studies have examined this association in the rest of the world. AIMS: To test the association between exposure to life events and psychosis in catchment areas in India, Nigeria, and Trinidad and Tobago. METHOD: We conducted a population-based, matched case-control study of 194 participants in India, Nigeria, and Trinidad and Tobago. Cases were recruited through comprehensive population-based, case-finding strategies. The Harvard Trauma Questionnaire was used to measure life events. The Screening Schedule for Psychosis was used to screen for psychotic symptoms. The association between psychosis and having experienced life events (experienced or witnessed) was estimated by conditional logistic regression. RESULTS: There was no overall evidence of an association between psychosis and having experienced or witnessed life events (adjusted odds ratio 1.19, 95% CI 0.62-2.28). We found evidence of effect modification by site (P = 0.002), with stronger evidence of an association in India (adjusted odds ratio 1.56, 95% CI 1.03-2.34), inconclusive evidence in Nigeria (adjusted odds ratio 1.17, 95% CI 0.95-1.45) and evidence of an inverse association in Trinidad and Tobago (adjusted odds ratio 0.66, 95% CI 0.44-0.97). CONCLUSIONS: This study found no overall evidence of an association between witnessing or experiencing life events and psychotic disorder across three culturally and economically diverse countries. There was preliminary evidence that the association varies between settings.