R G McCreadie

Incidence of schizophrenia in ethnic minorities in London: ecological study into interactions with environment

Abstract Objective: To determine whether the incidence of schizophrenia among people from non-white ethnic minorities is greater in neighbourhoods where they constitute a smaller proportion of the total population. Design: Ecological design including retrospective study of case records to calculate the incidence of schizophrenia in the ethnic minority population across electoral wards and multi-level analysis to examine interaction between individuals and environment. Setting: 15 electoral wards in Camberwell, South London. Participants: All people aged 16 years and over who had contact with psychiatric services during 1988-97. Main outcome measure: Incidence rates of schizophrenia according to Research Diagnostic Criteria. Results: The incidence of schizophrenia in non-white ethnic minorities increased significantly as the proportion of such minorities in the local population fell. The incidence rate ratio varied in a dose-response fashion from 2.38 (95% confidence interval 1.49 to 3.79) in the third of wards where non-white ethnic minorities formed the largest proportion (28-57%) of the local population to 4.4 (2.49 to 7.75) in the third of wards where they formed the smallest proportion (8-22%). Conclusion: The incidence of schizophrenia in non-white ethnic minorities in London is greater when they comprise a smaller proportion of the local population. What is already known on this topic An increased incidence of schizophrenia has been reported in several ethnic minorities in the United Kingdom Biological risk factors do not seem to explain this Reports from the United States have shown an association between the proportion of an ethnic minority living in an area and their admission rates for mental illness in general What this study adds The lower the proportion of non-white ethnic minorities in a local area the higher the incidence of schizophrenia in those minorities

Nithsdale schizophrenia surveys 21: A longitudinal study of national adult reading test stability

BACKGROUNDnThe stability of the National Adult Reading Test (NART) as a measure of pre-morbid intelligence in schizophrenia has not yet been satisfactorily established despite the widespread use of the NART in schizophrenia research.nnnMETHODnWe examined NART stability in a diverse group of 45 schizophrenic patients in a prospective longitudinal study over 6.5-7.5 years.nnnRESULTSnThe results showed that NART performance does not decline significantly with increasing duration of schizophrenic illness and that test-retest reliability, even over 6.5-7.5 years, is extremely high.nnnDISCUSSIONnOur results provide the necessary evidence that the NART can be used as a stable measure of pre-morbid intelligence in schizophrenia.

Schizophrenia is not disappearing in South West Scotland

BACKGROUNDnRecent work has reported a decline in the incidence of schizophrenia, but it is unclear if these findings reflect a true decrease in its incidence or are an artefact arising from methodological difficulties.nnnAIMSnTo take account of these methodological difficulties and report service-based incidence rates for schizophrenia in Dumfries and Galloway in south-west Scotland for 1979-98.nnnMETHODnUsing both clinical diagnoses and diagnoses generated from the Operational Checklist for Psychotic Disorders (OPCRIT) computer algorithm for ICD-10 and DSM-IV schizophrenia, we measured change in the incidence rates over time. We used indirect standardisation techniques and Poisson models to measure the rate ratio linear trend.nnnRESULTSnThere was a monotonic and statistically significant decline in clinically diagnosed schizophrenia. The summary rate ratio linear trend was 0.77. However, using OPCRIT-generated ICD-10 and DSM-IV diagnoses, there was no significant difference over time.nnnCONCLUSIONSnOPCRIT-generated consistent diagnoses revealed no significant fall in the incidence of schizophrenia. Changes in diagnostic practice have caused the declining rates of clinically diagnosed schizophrenia in Dumfries and Galloway.