Who Gets MS?
Many experts estimate that 2.5 million people worldwide have MS. The number of people diagnosed with MS in the United States was previously estimated more than a decade ago at 400,000. However, without a comprehensive, national registry, this figure cannot be confirmed and more research is needed. Most people with MS experience their first symptoms and are diagnosed between the ages of 15 and 50, although individuals of any age may be diagnosed with MS.
MS in childhood and adolescence is now being diagnosed more frequently, due in part to an increased awareness that children can get MS. Known as pediatric MS, diagnosis in children is still extremely involved, as experts have identified more than 40 common diseases that may initially behave similarly to early MS. In the United States, estimates range from 7,000 to 10,000 children and teens who have MS.
The distribution of this disease is not totally random. On average, with relapsing forms of MS, women are three times more likely than men to develop this disorder. With the primary-progressive form, genders are more equally divided.
Geographically, people who live farther from the equator (in more temperate climates) have a higher risk of developing MS than people living in hotter areas near the equator, or in very cold areas near the north or south poles. Individuals living beyond the 40-degree mark north or south of the equator are far more likely to develop MS, and this is especially true for people in North America, Europe, and southern Australia. The degree of risk associated with where someone lives as a child will remain throughout his or her life.
MS is very rare in Inuit populations (sometimes referred to as Eskimos) living in the far north. Asia continues to have a lower incidence of MS. More prevalent among those of northern European or Scandinavian ancestry, Caucasians have a higher incidence than those of African heritage to develop MS.
A recent study may show that African Americans are at a higher risk of MS than originally thought, but more research is needed. African-Americans tend to have more symptoms at the time of diagnosis, which are usually limited to the optic nerves and spinal cord, and this is termed “opticospinal MS.” This means that African-Americans may experience more problems with vision and mobility, versus other common MS symptoms. The disease course tends to be more progressive and responds less to disease-modifying therapies.
Research also reveals that Latinos are usually diagnosed at a younger age than both African-American as well as Caucasian Americans of non-Latino descent. Latinos tend to have fewer mobility and bladder/ bowel problems, but may experience more depression.
While MS is not contagious or hereditary, MS susceptibility is increased if a family member has MS. The average risk of developing MS in the United States is one in 1,000, or one-tenth of one percent. For firstdegree relatives (such as a child or sibling), the risk increases to three or four percent. This is not true for adopted children or half siblings (who do not share the same parent who has MS), whose risk is the same as unrelated individuals.
In situations where one identical twin has been diagnosed with MS, the other twin has a 31-percent risk of developing the disease. (If MS was strictly hereditary, when one identical twin has MS, the other identical twin would have a 100-percent risk of getting MS.) The risk for twins who are not identical is five percent – similar to that of other siblings. Other groups of individuals who appear to have an increased risk of developing MS include those who smoke cigarettes, individuals with less exposure to sunlight and with lower amounts of Vitamin D, as well as people living in cleaner environments with fewer parasites. These findings are explained later on page 8, under “Possible Causes of MS.”