| Abstrakt: |
OPEN ANY medical textbook, and it will tell you that multiple sclerosis prevalence varies with latitude: the further away from the equator, the greater one's risk of contracting it. This north-south gradient, noted in dozens of epidemiologic studies dating from the 1920s, traditionally has been thought to be due to some environmental factor more common in temperate climates.One investigator, using much of the same epidemiologic evidence, is questioning this dogma. He argues that the north-south gradient "at least in part, reflects ethnic migration and genetic susceptibility," rather than indicating the existence of an environmental trigger unique to northern climates.George C. Ebers, MD, is associate professor, Department of Clinical Neurological Sciences, University of Western Ontario, London. At the American Academy of Neurology meetings in New Orleans, he and co-investigator Dennis Bulman, a graduate student, presented results of an analysis of data from census surveys and studies of veterans conducted |
