Background: The incidence rate for broad schizophrenia among second-generation African-Caribbean people in the United Kingdom has been reported as high. Ethnicity, migration and psychosocial stressors have been suggested as causal factors.
Aims: To determine the incidence of schizophrenia for the whole population of Barbados using an identical methodology to two previous studies in Trinidad (Bhugra et al, 1996) and London (Bhugra et al, 1997).
Method: A 12-month study of all persons in the 18-54-year age group presenting with a psychosis for the first time was carried out on the population of Barbados. Information was collected using World Health Organization screening and measurement instruments.
Results: On an island of just over a quarter of a million, 40 out of the 53 patients that met the inclusion criteria were categorised as S+ (narrow) schizophrenia, giving an incidence rate of 2.8/10,000 (95% CI 1.97-3.7). The incidence rate for broad schizophrenia was calculated at 3.2/10,000 (95% CI 2.3-4.1), which is significantly lower than the comparable rate for London's African-Caribbeans of 6.6/10,000 (95% CI 4.5-8.7).
Conclusions: The very high rate for broad schizophrenia among African-Caribbean people in the UK is probably due to environmental factors.