Around 1 million people are living with multiple sclerosis (commonly known as MS) in the United States, and about 2.8 million people around the world have the disease. While doctors still aren’t sure what causes MS, they continue to explore who has the disease, who’s more likely to get it, and what could raise your odds.
MS is a disease that affects the brain and spinal cord. While there are many medications available to treat symptoms of MS, it can still cause varying levels of disability, impact your ability to function and work, and cause fatigue and pain. By figuring out what causes MS, doctors and researchers hope to improve treatments for the disease, find a cure, and eventually keep it from happening in the first place.
MS is not contagious or passed down through your family. Doctors and scientists believe a series of things cause it and continue to study how age, gender, race, genetics, and other factors play a role. They’re also exploring the immune system, infectious diseases, and the distribution of different types of MS around the world.
While doctors are diagnosing more people with MS today than in the past, researchers don’t believe that the rate of MS is on the rise. They think the higher number of diagnosed cases is due to greater awareness of MS, more access to medical care, and better tools, knowledge, and resources to diagnose people with the disease.
Who Is Most Likely to Have MS?
While doctors don’t know exactly what causes MS, studies have shown that some people have a higher chance of forming the disease based on certain things. These include:
Age: Doctors diagnose most people with MS between the ages of 20 and 50, but young children and older adults also get it. MS in children is rare. In the U.S., fewer than 5,000 kids have it, while globally that number rises a bit to 10,000. Children only get one type of MS: Relapsing-Remitting MS (RRMS). This means they have cycles of “attack” -- times when they have symptoms, and times when symptoms ease or are in remission.
Gender: Based on a 2017 study, 74% of people with MS were female. Women are about three times more likely to get MS than men, which hints at a hormonal reason for MS.
Geography: MS generally tends to be more prominent in places farther away from the equator. A 2016 study found that most MS cases worldwide are in North America and Europe, and the lowest rates of MS are in Eastern Asia and sub-Saharan Africa.
Ethnicity: MS occurs in most ethnic groups. But it is most common in whites with northern European roots. New research has shown that African American women have a higher chance of having the disease than previously understood.
Lifestyle: Doctors and scientists are studying other things that may cause MS or make it worse. They include low vitamin D levels, smoking, and obesity -- especially for young girls and women living with obesity during their childhood and teen years. All of these things may mean you’re more likely to get the disease.
Viruses and bacteria: Doctors have also found that people exposed to certain viruses and bacteria have higher odds of forming MS. This includes exposure to measles, pneumonia, canine distemper, human herpes virus-6, Epstein-Barr virus (EBV), and Chlamydia pneumonia. Recently, several studies have provided further evidence that people who’ve had the EBV infection are much more likely to form the disease.
How Common Are Different Types of MS?
Although there’s no way to predict how MS will advance for different people, researchers have identified three forms of the disease. Doctors diagnose you after getting your history and doing a complete examination, neurologic tests, and by using magnetic resonance imaging (MRI), which scans the brain and spinal cord. A majority of people with MS have an abnormal MRI.
Relapsing-Remitting MS (RRMS): This is the most common type of MS. About 85% of people with MS have this form of the disease at first.
People with RRMS have “attacks” or times when they have new or increasing neurologic symptoms. These attacks -- also called relapses happen before periods of few or no symptoms (also called remission).
Secondary Progressive MS (SPMS): This type of MS happens in people who already have RRMS. Doctors consider it an advancement of RRMS and diagnose SPMS when you have worsening neurologic function, disability, or symptoms. People with SPMS tend to no longer have relapses, but their disease will steadily get worse due to nerve damage or loss.
Unfortunately, it is not possible to predict who may get SPMS. Researchers believe about 50% of people who have RRMS will get SPMS within 10 years, and 90% of people with RRMS will transition into SPMS within 25 years of having MS. Doctors believe MS medications may help slow the disease, but there’s no certainty.
Primary Progressive MS (PPMS): This type of MS is when people have worsening neurologic function and disability at the start of their MS. They usually don’t have “attacks” of symptoms but rather a more steady decline of the disease over time.
People with this type of MS also tend to have more lesions affecting their spinal cord and fewer that impact their brain. This leads to more trouble walking, working, and performing everyday activities.
Women and men get PPMS in equal numbers. People with this type of MS generally see the start of the disease about 10 years later than those with relapsing MS.