Age at immigration to England of Asian and Caribbean immigrants and the risk of developing multiple sclerosis

Objectives-Previous studies have shown that multiple sclerosis is very uncommon among Indian and Pakistani immigrants to England but that their children born in the United Kingdom, in the age groups available for study, have a similar risk of developing the disease as occurs in the general British population. The present study was to ascertain if these immigrants who enter England as children below the age of 15, have a higher risk of developing multiple sclerosis than those that enter after this age. Methods-A search was made in Greater London, the West Midlands, Leicester, Bradford, Halifax, and Huddersfield to find ethnic Indian, Pakistani, and Bangladeshi immigrants to England with multiple sclerosis. During the course of the study some immigrants from the Caribbean with multiple sclerosis were also found. The population at risk by ethnic group and age at entry was not available from the 1991 Census but was available in the annual Labour Force Surveys. Results-Indian and Pakistani immigrants who entered England younger than 15 had a higher risk of developing multiple sclerosis than those that entered after this age. Caribbean immigrants, who have a higher multiple sclerosis prevalence than Asian immigrants, did not show this difference. Conclusion-This study confirms previous studies which shaw that the environment during childhood is a major factor in determining the risk of developing multiple sclerosis.