Multiple sclerosis (MS) is a chronic, immune-mediated disorder that affects around 1 million people in the United States and 150,000 people in the United Kingdom. The global prevalence of MS (the number of people living with MS worldwide) is approximately 2.9 million.

MS causes your immune system to mistakenly attack your own body’s cells within the central nervous system (CNS), affecting the spinal cord, nerves, and other components of the brain. The immune system attacks and destroys the protective myelin coating on the nerve cells, a process called demyelination. People with MS can develop lesions, which can lead to irreversible damage of the nerve fibers and varying degrees of physical disability.

Prompt diagnosis and proper treatment are recommended to prevent future MS relapses, reduce symptoms, and improve the overall disease course. While there is currently no cure for MS, treatment options can control the disease progression.

What Causes MS?

At present, researchers are not sure of the exact cause of multiple sclerosis. A combination of factors trigger the autoimmune response associated with the condition. Those factors include include:

• Genetic factors — More than 230 genes may be related to MS.
• Viral infections — Several viruses, including the Epstein Barr virus, are being researched for possible links to MS.
• Environmental factors — Long-term exposure to certain toxins, stress, tobacco products, and vitamin D deficiency may also increase susceptibility to MS.

Significant scientific research is underway to determine how much each factor contributes to MS progression.

Which Groups Are More Likely To Have Multiple Sclerosis?

MS can affect people of all ages, ethnicities, and genders. That said, the condition is more prevalent among certain groups of people.

Adults

Most cases of MS are diagnosed in people between the ages of 20 and 50 years. However, the onset of MS can occur at any age — including in young children.

People Who Live Farther From the Equator

The Multiple Sclerosis International Federation maintains an interactive atlas of the geographic distribution of MS. The prevalence of people with MS increases as you travel farther north or south from the equator. Multiple sclerosis is most common in the following areas:

• Europe
• The U.S.
• Canada
• Scotland
• New Zealand
• Parts of Australia

Areas of Asia and Africa that lie on the equator have extremely low levels of MS. MS is very rarely seen in people of Inuit descent who live far up north.

Certain Ethnic and Racial Groups

Multiple sclerosis occurs in almost all ethnic groups. According to the National Multiple Sclerosis Society, “MS is most common among white people with northern European roots, but it occurs in most ethnic groups, including African Americans, Asian Americans, and Hispanics/Latinx.”

According to the National Multiple Sclerosis Society, “There is some evidence that MS symptoms can be different in range and severity for Black people.” This evidence includes:

• Higher risk of developing MS, notably for Black women
• Disease onset at a later age
• More MS symptoms at diagnosis, especially MS-related vision problems and mobility issues

A study in the medical journal Neurology analyzed health care data from approximately 3.5 million insured Americans over a three-year period. In that time, 496 of those individuals were diagnosed with MS. Of the people diagnosed with MS, 70 percent were women.

Among the 496 individuals diagnosed with MS, Black people were found to be at a 47 percent higher risk of developing the condition than white people. Hispanic people were found to have a 50 percent lower risk, and Asians had an 80 percent lower risk for MS than white people. The study also determined that while Black men were about as susceptible to MS as white men, Black women had at the greatest risk of MS.

People With Other Diseases of the Immune System

Having one or more additional autoimmune conditions can increase your risk of developing MS. That includes:

• Psoriasis
• Type 1 diabetes
• Lupus
• Certain thyroid problems
• Inflammatory bowel disease

Women

Data suggests that the relapsing type of MS affects more women than it does men. Women are three times as likely to have a relapsing form of MS than men. The difference is smaller between men and women in progressive forms of MS, such as primary-progressive MS.

Physicians are not yet sure of the reason for this difference in MS incidence between men and women. Researchers believe it may be connected to sex hormones, such as testosterone and estrogen.

What Are the Risk Factors for Developing Multiple Sclerosis?

Among the general population of the U.S., the average risk of developing MS is approximately 3 in 1,000 — less than one half of 1 percent. MS susceptibility is affected by many factors. Risk varies for different groups of people.

Genetic Risk Factors

To date, scientists have identified 230 genes linked to MS. Of these 230 genes, no single gene or genetic mutation is responsible for causing the condition. Rather, a person’s likelihood of developing MS is influenced by which and how many of these 230 genes are impacted. Research is ongoing in this area.

Does MS Run in Families?

MS is not a hereditary condition. In other words, one does not inherit MS from their parents or other first-degree biological relatives. That said, one’s risk of developing MS is greater if a family member has MS.

My Identical Sister Has MS Too

Dani Darling and Jacqui Blue, who are triplets along with another sister, have both been diagnosed with relapsing-remitting multiple sclerosis (RRMS).

Transcript

00:00:00:00 - 00:00:27:15
Dani Darling
When I found out that my sister Jacqui had MS, I was devastated because I had just been diagnosed, so I knew what was happening, and I felt like having gone through it, that the last thing I wanted was for anyone to go through what I went through.

Jacqui Blue
We are two of three identical triplets.

Dani Darling
Yes, I’m the oldest by one minute.

Jacqui Blue
And I’m the middle, and the oldest of Nikki, our last sister,

00:00:27:15 - 00:00:55:04
Jacqui Blue
by 30 seconds.

Dani Darling
We started making music together

Jacqui Blue
in the womb. [laughing] No, I’m kidding. Like three.

Dani Darling
Before we could even do complete complex sentences, we were harmonizing.

Jacqui Blue
We were singing.

Dani Darling
As triplets, there were a lot of things that we didn’t want to share like, you know, when you’re a kid, you have to split your cake and blow your candles out together. So there’s things that you just don’t want to share,

00:00:55:04 - 00:01:15:09
Dani Darling
and I think MS was one of those things.

Jacqui Blue
Dani was diagnosed in September, and then I was diagnosed that next February,

Dani Darling
about six or seven months later, but the thing that we found out was that we’d both had it for years.

Jacqui Blue
Yeah.

00:01:15:11 - 00:01:36:07
Dani Darling
What Nikki has is called RIS, and Jacqui has multiple sclerosis, and I’m not sure when or what her story would have been, or what her diagnosis would have been like if I hadn’t been the first one to find out that I had that. Before we both had it, you were like coaching me in resiliency, like, Jacqui’s a music therapist.

00:01:36:12 - 00:01:59:00
Dani Darling
She was like “You’re going to be OK.” That was actually the most important, I think, factor to me, being able to pick myself up and keep going was that, like, resilience training that you gave me.

Jacqui Blue
Yeah. That’s true. There are steps you can take, and it’s very important, and reaching out for help is one of them. Be honest with your feelings and talking things through.

00:01:59:00 - 00:02:22:22
Jacqui Blue
Stay active mentally and physically active. There are steps you can take to bounce back, and so we are — we’re doing them.

Dani Darling
I’m Dani Darling, and I have relapsing-remitting multiple sclerosis.

Jacqui Blue
I’m Jacqui Blue, and I have relapsing-remitting multiple sclerosis.

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For comparison, the lifetime risk of developing MS among the general population is less than half of 1 percent. If a first-degree relative has MS, the risk increases to between 3 percent and 4 percent. If one identical twin has a diagnosis of MS, the other twin has a 1 in 5 chance of developing MS. Nonidentical twins carry a lower likelihood of developing MS, with a 1 in 22 chance. If your biological sibling, meaning you share the same mother and father, has been diagnosed with MS, your odds of developing the condition are 1 in 37. If your parent has MS, the odds of you developing MS are 1 in 67.

Environmental Risk Factors

Environmental factors may also affect whether a person will develop MS.

Tobacco Smoking

According to the Multiple Sclerosis Association of America, women who smoke are 1.6 times more likely to develop MS than women who don’t smoke. Individuals with MS who smoke also appear to be at greater risk of more rapid disease progression.

Sun Exposure and Vitamin D

Vitamin D deficiency and exposure to sunlight may lower one’s risk of developing MS. Data suggests that people who take at least 400 international units of vitamin D daily are at lower risk of developing MS. Populations exposed to more sunshine or ultraviolet rays appear to have lower rates of MS.

Talk With Others Who Understand

MyMSTeam is the social network for people with multiple sclerosis and their loved ones. On MyMSTeam, more than 216,000 members come together to ask questions, give advice, and share their stories with others who understand life with MS.

Are you living with multiple sclerosis? Have you noticed any of these risk factors in your own life? Share your experience in the comments below, or start a conversation by posting on your Activities page.