Connect with others who understand.

sign up log in
Resources
About MyMSTeam

Causes of Multiple Sclerosis

Updated on February 04, 2022
Medically reviewed by
Evelyn O. Berman, M.D.
Article written by
Aminah Wali, Ph.D.

The cause of multiple sclerosis (MS) is unknown. Scientists have proven that MS is autoimmune in origin. In other words, the damage in MS is caused by the body’s immune system attacking its own tissues, but scientists have not yet figured out why this process begins.

Autoimmune attacks in MS are directed at the tissues of the central nervous system, specifically the myelin sheath that surrounds nerve fibers of the spinal cord, brain, and optic nerve. MS damages the myelin sheath and sometimes the nerve cells as well, leading to MS symptoms like vision problems, spasticity, and muscle weakness.

Although researchers have established that both hereditary and environmental factors influence a person’s risk of developing MS, no one has identified why some people are diagnosed with MS and some aren’t. Most scientists believe MS is most likely caused by a combination of inherited and environmental factors.

Risk Factors for MS

Science is good at finding correlations — or apparent relationships — between factors and disease, but correlation does not prove that the factor causes the disease. Many risk factors for MS have been identified and are being studied, but none has been pinpointed as the cause of MS.

Genetic Factors

MS does not appear to be directly inherited from parents in any clear genetic pattern. However, people with a parent or sibling who has MS have a higher risk of developing the disease. The average person’s risk of developing MS is 0.2 percent.

If someone has a sibling with MS, their risk of developing MS is between 2 percent and 4 percent. In identical twins, if one twin is diagnosed with MS, the other twin has up to a 30 percent chance of developing the condition. Research to better understand genetic susceptibility for MS is ongoing.

Gender

Women are about three times as likely as men to develop MS. In general, there is a greater prevalence of autoimmune disease in females than males. In the United States, 75 percent of those with an autoimmune disease are women.

Women’s immune systems are believed to be more effective than men’s, giving women greater protection from infections, but making them more vulnerable to autoimmune disorders.

Race and Ethnicity

Ethnicity may influence MS predisposition. A research study from Multiple Sclerosis found that MS “has a strong racial and ethnic component and disproportionately affects whites of European background.” It also found that rates are increasing among African Americans, Hispanics, and Asians.

These groups may also experience symptoms differently and vary in the typical age at diagnosis relative to whites. Some ethnic groups, such as the New Zealand Maori and other indigenous peoples, have a low incidence of MS.

Environmental Factors

Researchers have identified a wide array of environmental factors linked to the development of MS.

Geography

One interesting environmental factor, and among the first to be discovered, is geography. The farther a place is from the equator, the more common MS will be. Conversely, MS is very rare in areas near the equator.

Similarly, the farther from the equator someone lives, the earlier they begin experiencing MS symptoms. If a person moves from a lower-risk latitude to a higher-risk latitude in childhood, their risk of developing MS rises accordingly. Moving from a high-risk to a lower-risk area in early life decreases overall risk.

The geographic difference in risk for MS has led scientists to study links between vitamin D and MS. Because people nearer the equator get more sunlight throughout the year, their skin makes more vitamin D.

Studies have established a link between low levels of vitamin D and the development of MS. Current research explores whether vitamin D supplementation can help those who already have MS or prevent the disease from developing by supplementing with vitamin D in childhood.

Some researchers connect the geographic factor with diet. Populations in lower-risk areas tend to live nearer the ocean and consume more fish. Salmon, mackerel, herring, and sardines are rich in vitamin D as well as omega-3 fatty acids, which are believed to reduce inflammation. Diets that are low in saturated fat and emphasize lean protein and fresh produce have been shown to improve MS symptoms.

Smoking

Past or present cigarette smoking makes a woman at least 1.6 times more likely to develop MS, and the risk rises with the number of packs per day. Studies also show that MS progresses more rapidly in those who currently smoke compared to nonsmokers.

Age

Age is a risk factor, with most cases of MS diagnosed between the ages of 20 and 40. It is less common for MS to be diagnosed in older adults and rare for MS to be diagnosed in children. Pediatric cases account for only 2 percent to 5 percent of MS.

Viral Infection

Several studies have investigated specific viruses for links with MS. Some scientists believe that one or more common viruses such as the Epstein-Barr virus (the cause of mononucleosis, or “mono”), varicella-zoster (a herpes virus responsible for chickenpox and shingles), human herpesvirus-6 (cause of roseola), and the measles virus may cause genetic changes in some people, paving the way for the development of MS.

Injury

Researchers have found a correlation between head trauma experienced between ages 10 and 20 and later development of MS. Those who had suffered concussions were more likely to have MS as adults. Multiple concussions further raised the risk.

Seasonal Factors

One study in Finland found that people born in the spring had a higher risk of developing MS. The researchers theorized that women pregnant during the winter received less vitamin D due to lower sun exposure, and the lower levels of vitamin D in the womb may have predisposed their children to develop MS.

Condition Guide

References
  1. What Causes MS? — National Multiple Sclerosis Society
  2. What Is Myelin? — National Multiple Sclerosis Society
  3. Stress and the Risk of Multiple Sclerosis — Neurology
  4. Correlation and Causation — Understanding Health Research
  5. The Genetics of Multiple Sclerosis — Multiple Sclerosis: Perspectives in Treatment and Pathogenesis
  6. Who Gets MS? (Epidemiology) — National Multiple Sclerosis Society
  7. Sex Differences in Immune Responses — Nature Reviews Immunology
  8. Race and Ethnicity on MS Presentation and Disease Course: ACTRIMS Forum 2019 — Multiple Sclerosis
  9. Multiple Sclerosis Research Group — New Zealand Brain Institute
  10. Lower Prevalence of Multiple Sclerosis in First Nations Canadians — Neurology: Clinical Practice
  11. Vitamin D and Multiple Sclerosis: A Comprehensive Review — Neurology and Therapy
  12. Risk of Developing MS — Multiple Sclerosis Trust
  13. What Is Autoimmunity? — American Autoimmune Related Diseases Association
  14. Study Shows Distance From the Equator Linked to Age of When a Person Develops MS — National Multiple Sclerosis Society
  15. Vitamin D, Biotin & Omega-3 — National Multiple Sclerosis Society
  16. Who Gets Multiple Sclerosis — Multiple Sclerosis Association of America
  17. Multiple Sclerosis — Mayo Clinic
  18. Pediatric MS — National Multiple Sclerosis Society
  19. Viral Infections and Multiple Sclerosis — Drug Discovery Today: Disease Models
  20. Childhood Head Trauma and Risk of Subsequent Diagnosis of Multiple Sclerosis — Relias Media
  21. Vitamin D Status During Pregnancy and Risk of Multiple Sclerosis in Offspring of Women in the Finnish Maternity Cohort — JAMA Neurology
All updates must be accompanied by text or a picture.
Evelyn O. Berman, M.D. is a neurology and pediatric specialist and treats disorders of the brain in children. Review provided by VeriMed Healthcare Network. Learn more about her here.
Aminah Wali, Ph.D. received her doctorate in genetics and molecular biology from the University of North Carolina at Chapel Hill. Learn more about her here.

Related articles

Multiple sclerosis (MS) is an autoimmune disease in which the body’s own immune system attacks...

Why Are Women More Likely To Develop Multiple Sclerosis?

Multiple sclerosis (MS) is an autoimmune disease in which the body’s own immune system attacks...
New research has found evidence that Epstein-Barr virus (EBV) infection may be a cause of...

Epstein-Barr Virus: A Link Between MS and Cancer

New research has found evidence that Epstein-Barr virus (EBV) infection may be a cause of...
Recent research shows that the Epstein-Barr virus (EBV) may be the leading cause of multiple...

Are Low Vitamin D, Smoking, and Epstein-Barr a Perfect Storm for MS?

Recent research shows that the Epstein-Barr virus (EBV) may be the leading cause of multiple...
For many years, people of European ancestry were believed to develop multiple sclerosis (MS) more...

Multiple Sclerosis and Ethnicity: Is Race a Risk Factor in MS?

For many years, people of European ancestry were believed to develop multiple sclerosis (MS) more...
Multiple sclerosis (MS) is thought to be caused by a combination of factors — genetics, immune...

Mapping MS: Where Is Multiple Sclerosis Most Common, and Why?

Multiple sclerosis (MS) is thought to be caused by a combination of factors — genetics, immune...
Multiple sclerosis (MS) is a neurological disease — that is, a condition affecting the nerves and...

Head Trauma and Multiple Sclerosis: Do Brain Injuries Raise the Risk for MS?

Multiple sclerosis (MS) is a neurological disease — that is, a condition affecting the nerves and...

Recent articles

Many symptoms can go along with an autoimmune disease like multiple sclerosis (MS). Everyone’s MS...

Can MS Affect the Skin? Dryness, Lesions, and More

Many symptoms can go along with an autoimmune disease like multiple sclerosis (MS). Everyone’s MS...
If you have multiple sclerosis (MS), you may wonder about the therapeutic potential of lion’s...

Lion’s Mane Mushroom: Is It Effective and Safe for MS Symptoms?

If you have multiple sclerosis (MS), you may wonder about the therapeutic potential of lion’s...
Some people with multiple sclerosis (MS) find that they repeatedly bite their tongue, lips, or...

Can Biting Your Tongue Be a Symptom of MS?

Some people with multiple sclerosis (MS) find that they repeatedly bite their tongue, lips, or...
People with multiple sclerosis (MS) sometimes develop comorbidities (secondary diseases). Some...

ITP and MS: Can Multiple Sclerosis Cause This Bleeding Disorder?

People with multiple sclerosis (MS) sometimes develop comorbidities (secondary diseases). Some...
Feelings of numbness and tingling are common symptoms of multiple sclerosis (MS). Not only can...

Numbness and Tingling in MS

Feelings of numbness and tingling are common symptoms of multiple sclerosis (MS). Not only can...
If you’re living with multiple sclerosis (MS), you may have experienced a common symptom of the...

Costochondritis vs. MS Hug: What’s the Difference?

If you’re living with multiple sclerosis (MS), you may have experienced a common symptom of the...
MyMSTeam My multiple sclerosis Team

Thank you for signing up.

close