Ethnic density is unrelated to incidence of schizophrenia.

Data deriving from the Mental Health Enquiry were obtained from the Department of Health and Social Security (DHSS) for all 186,000 admissions in England in 1981 to test the 'ethnic density hypothesis'. This hypothesis has been used to explain variations in rates of mental illness between ethnic groups in other countries, and suggests that there is an inverse relationship between the size of ethnic groups and their admission rates. The data analysed in the present paper for the main foreign-born immigrant groups to England not only failed to support the ethnic-density hypothesis, but in some cases, showed a significant positive relationship between group size and admission rates. Some possible reasons for these findings are explored.