• Topic Overview
• Related Information
• References
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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.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.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

• Multiple Sclerosis (MS)

References

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