Multiple Sclerosis and Geographic Location

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Topic Overview

The number of people who have multiple sclerosis (MS) increases the farther away they are from the equator.

In areas near the equator, MS occurs in fewer than 1 out of 100,000 people. In areas farther from the equator—such as northern Europe and northern North America—MS occurs in around 30 to 80 out of 100,000 people.footnote 1 When moving south of the equator, the number of people with MS is less dramatic, but the same trend is seen.

Some evidence suggests that people who move from a high-risk to a low-risk area before the age of 15 reduce their chances of developing MS. But the same is true in reverse. In those who move from a low-risk area to a high-risk area before the age of 15, the risk of getting MS increases. Those older than 15 when they move to a new area retain the risk associated with their old area.footnote 1

Most experts agree that this unusual relationship between geographic location and MS suggests that an environmental factor is partly responsible for causing the disease.

Related Information

References

Citations

  1. Ropper AH, Samuels MA (2009). Multiple sclerosis and allied demyelinative diseases. In Adams and Victor's Principles of Neurology, 9th ed., pp. 874–903. New York: McGraw-Hill.

Other Works Consulted

  • Spelman T, et al. (2014). Seasonal variation of relapse rate in multiple sclerosis is latitude dependent. Annals of Neurology, published online October 4, 2014. DOI: 10.1002/ana.24287. Accessed October 31, 2014.

Credits

ByHealthwise Staff
Primary Medical Reviewer Adam Husney, MD - Family Medicine
Anne C. Poinier, MD - Internal Medicine
Specialist Medical Reviewer Barrie J. Hurwitz, MD - Neurology

Current as ofFebruary 20, 2015