So does that mean that the nearly 1 million people living with MS could have avoided getting this chronic autoimmune disease? Based on what experts know about MS, the answer is no — or at least not yet. One reason that effective prevention measures have yet to be developed is that the cause of multiple sclerosis is multifactorial: There’s no one thing that we know of that causes MS, says Emily Harrington, MD, PhD, a neurologist at the Ohio State University Wexner Medical Center in Columbus. “It’s thought that MS is caused by a combination of genetic and environmental factors,” says Dr. Harrington. There is also evidence to suggest that people at risk of developing MS have differences in their immune system, she says. “Hopefully in the future we can develop ways to prevent MS from developing. We are not there yet, but I think we are getting closer to developing biomarkers and other ways of catching MS early and preventing it,” Harrington says. People with a parent, non-twin sibling, or child with MS also have a higher risk. According to the National Multiple Sclerosis Society, while the average person in the United States has a 1 in 750 (0.13 percent) chance of developing MS, the risk rises to 2.5 to 5 percent for first-degree relatives of people with MS. Researchers at the University of British Columbia and Vancouver Coastal Health in Canada announced study results in June 2016 that showed that, in rare cases, MS can be caused by a single genetic mutation. Only 1 in 1,000 people with MS appears to have this mutation, which causes a rapidly progressive type of MS, and not everyone with the mutation gets MS. Senior author Carles Vilariño-Güell, PhD, an assistant professor of medical genetics and member of the Djavad Mowafaghian Centre for Brain Health at the University of British Columbia, said in a press release, “This mutation puts these people at the edge of a cliff, but something still has to give them the push to set the disease process in motion.” That something might be a virus, a lack of vitamin D in the body, smoking, or something else entirely.
Common Viruses May Raise Your Risk of MS
It’s thought that there are probably things that set off the immune system that can cause someone to develop MS, says Harrington. Decades of research has shown a link between Epstein-Barr virus (EBV), a member of the herpes family of viruses, and MS, although it has not conclusively been identified as a cause. A study published in 2020 in the Journal of Neurology, Neurosurgery and Psychiatry found that every single patient selected from a database of people with early MS tested positive for antibodies to EBV. The authors concluded that if a person is suspected to have MS but has negative EBV serology, a diagnosis of a condition other than MS should be considered. But EBV is extremely common. In fact, the Centers for Disease Control and Prevention reports that most people get infected with this virus at some point in their lives. In children, EBV looks just like the common cold; in adolescents and adults, it can develop into mononucleosis, which typically causes severe fatigue, fever, muscle aches, sore throat, and swollen lymph nodes in the neck and armpits. Symptoms of mononucleosis can last for weeks. Another common virus that’s been linked to MS is human herpesvirus 6 (HHV-6), according to the National Multiple Sclerosis Society. In research published in the journal PLoS One, researchers found that higher HHV-6 antibody levels in the body were associated with an increased risk of MS relapses. Although HHV-6 has not been shown to trigger the onset of MS, there is growing evidence that HHV-6A, a type of HHV-6, may have a role in MS development. A study published in November 2019 in Frontiers in Immunology discovered that antibodies contained in the blood showed that people with MS carry the herpesvirus 6A to a greater extent than people without MS. RELATED: What Does the Epstein-Barr Virus Have to Do With MS? This may be related to sun exposure and vitamin D levels in the body, she says. Vitamin D is known as the sunshine vitamin because the human body generates it in response to sunlight. “Vitamin D deficiency is associated with a higher risk of developing MS, but that alone doesn’t cause MS. We check the level of vitamin D in people with MS, and we supplement if it’s too low,” says Harrington. According to a review published in June 2018 in Neurology and Therapy, the existing evidence on vitamin D and MS suggests that having normal vitamin D levels may reduce the risk of MS and affect the course of the disease, but additional studies are needed to confirm and understand this association. One study published online in September 2017 in the journal Neurology found that women who had deficient levels of vitamin D — defined in the study as fewer than 30 nanomoles per liter — were 43 percent more likely to develop MS than those with normal levels of the vitamin. Commenting in a press release from the American Academy of Neurology, study author Kassandra L. Munger, a doctor of science in nutritional epidemiology at the Harvard T. H. Chan School of Public Health in Boston, said, “Our study, involving a large number of women, suggests that correcting vitamin D deficiency in young and middle-aged women may reduce their future risk of MS.”
Smoking Is Associated With an Increased Risk of MS
There is evidence that the risk of developing MS is higher in former or current smokers, says Harrington. In general, smokers get more autoimmune conditions, says the Cleveland Clinic, and MS is considered to be an autoimmune condition. A meta-analysis published in 2016 in the journal PeerJ estimated the risk of developing MS was increased by 50 percent in “ever smokers.” “Smoking is also associated with having a worse outcome if you have MS; we recommend if someone with MS is a smoker, that they stop,” says Harrington.
Childhood Obesity Could Be One Factor in Developing MS
Although we can’t go back in time and change our past weight or diet, there is evidence that childhood obesity is a risk factor for MS, says Harrington. A study published in January 2020 in Neurology Neuroimmunology & Neuroinflammation strengthened the findings of existing research on this relationship through a method called Mendelian randomization. By examining genetic variants, investigators determined that body mass index before age 10 is an independent causal risk factor for developing MS. Additional reporting by Becky Upham.
