What Causes MS? Doctors Explain Symptoms, Conditions, and Other Things You’ll Want to Know
Let’s jump in: Multiple sclerosis is an autoimmune disease affecting the brain and spinal cord. The condition occurs when your immune system does not recognize myelin, the fatty white layer coating the nerve fibers in your brain and spinal cord, as part of your body. Mistaking myelin as a foreign invader, white blood cells attack it. As more myelin gets destroyed, so does communication from the brain to the rest of the body.
Nearly 2.8 million people live with multiple sclerosis—a 30% increase from estimates in 2013. The number has grown in every country and is expected to keep growing. Multiple sclerosis can happen at any age, and there are various causes that can contribute to the development of the disease. Here’s what you need to know about it, from causes to symptoms—and when to see a doctor.
What causes multiple sclerosis?
No two multiple sclerosis cases are the same, says Mary Ann Picone, M.D., a neurologist specializing in multiple sclerosis at Holy Name Medical Center. Some people may lose their ability to walk or talk, while others might feel fatigue or a tingling sensation in multiple parts of the body. “Where there’s loss of myelin in the brain and the spinal cord, how much myelin is lost, and how much inflammation is present can cause people to have different symptoms.” Here are the most common causes of multiple sclerosis:
Genetics
Dr. Picone says people who have a family history of multiple sclerosis have a higher chance of developing the disease in life. The risk gets even higher if a close family member—a parent or sibling—has multiple sclerosis.
Multiple genes contribute to a risk of multiple sclerosis. Josef Gutman, M.D., a neurologist and director of the NYU Long Island Comprehensive Multiple Sclerosis Center, says some immune system genes known as HLA genes are associated with some risk for multiple sclerosis. Though he cautions that having these genes does not mean you’ll automatically get the disease. “It’s not like the BRCA gene for breast cancer,” he explains. “They don’t carry a large significant risk to make it worth testing for clinically.”
Vitamin D levels
Sharon Stoll, D.O., a neurologist specializing in multiple sclerosis and neuroimmunology at Yale School of Medicine, says there is a strong association between low vitamin D levels and an increased risk of having multiple sclerosis. Vice versa, high vitamin D levels mean less risk. Because high vitamin D levels seem essential for prevention, Dr. Stoll says you’re more likely to see cases in areas far from the equator. This is because being away from the equator means less sun, and, in turn, less vitamin D.
Though Dr. Picone does point out that this link has grown weaker in the last decade, where there seems to be more multiple sclerosis cases in tropical areas such as Puerto Rico. “Even though there’s a lot of sun exposure, it may have to do with the sun [glaring strongly] and everyone is wearing sunscreen to prevent skin cancer,” she explains. “But sunscreen means less absorption of vitamin D from sunlight.” Dr. Stoll points out that in hot climates like the Middle East, multiple sclerosis cases may be rising because people tend to cover up, blocking sun exposure.
Epstein-Barr virus
A research study made headlines earlier this year when they found that infection from the Epstein-Barr virus is one of the leading causes of multiple sclerosis. “Early exposure to Epstein-Barr virus is not necessarily the trigger,” clarifies Dr. Stoll. “But it’s needed to have multiple sclerosis.”
Epstein-Barr virus is very common with about 90% of the world’s population infected with the virus. Though Dr. Stoll says that does not mean 90% of people will go on to develop multiple sclerosis because other triggers influence disease risk. Instead, the scientific evidence shows that Epstein-Barr infection, especially in the teenage years, greatly elevates your risk of getting multiple sclerosis later in life.
“This may mean we might develop a vaccine for Epstein Barr Virus that could also help in the prevention of multiple sclerosis in the future,” adds Dr. Picone.
Common misconceptions about multiple sclerosis causes
Several genetic and environmental factors raise a person’s risk for multiple sclerosis. But there are some fallacies over other alleged causes of multiple sclerosis.
COVID-19 infection
While neurologists agree that a viral or bacterial infection can flareup or worsen any underlying symptoms, specifically having a COVID-19 infection does not make you more susceptible to multiple sclerosis. “It seems like more of a rarity, which is surprising because as stressful as COVID is on the body and mentally, you would expect to more relapses and spinal lesions,” says Dr. Stoll. “Eight percent of my patients had COVID and not many people have had relapses.”
Mercury
There is no credible scientific evidence that links heavy metal exposure to multiple sclerosis. Dr. Picone says because of this misconception, some of her patients had all of their fillings removed—a small amount of mercury is used to bind silver, tin, and copper together to make a solid and durable dental filling—because of the misperception that liquid mercury worsens the progression of disease.
Pregnancy
Dr. Picone says one of the biggest misconceptions she sees among patients is that you have to avoid getting pregnant or else you’ll cause a relapse or worsening of disease activity. She says that technically, there is an increased risk for a relapse after childbirth, but with the number of multiple sclerosis treatments available, the condition is manageable.
“You can definitely get pregnant, and many patients I’ve seen have gone on to have healthy children and a full recovery,” Dr. Picone explains. “But that’s definitely a misconception, and so many patients have been told that they shouldn’t get pregnant.”
Multiple factors influence your risk of MS
Whether you have a family history of multiple sclerosis or not, there are other variables that can greatly raise your risk of developing it.
Smoking
Dr. Picone says smoking impacts multiple sclerosis risk because of the inflammation it causes the body. A March 2022 study in Frontiers in Immunology found that 13% of multiple sclerosis cases could have been prevented by avoiding cigarettes.
According to the National Multiple Sclerosis Society, smoking and exposure to secondhand smoke can promote relapses because they stop the body from properly processing different types of multiple sclerosis treatment, decreasing their effectiveness. Smoking also leads to worsening or disabling symptoms and more disease activity.
Stress
Stress can put a strain on your body, and has been linked to impaired immune function and susceptibility to a number of different infections and diseases. While still a topic of exploration, there are some studies pointing to a possible connection.the connection between stress and multiple sclerosis. A 2020 study published in the European Journal of Neurology suggest that unexpected and stressful life events increased disease risk by 17%-30%. The stressful life events tended to happen in the past five years and affected women more.
Gender
Dr. Stoll says multiple sclerosis diagnoses happen in women more than men. Primary progressive multiple sclerosis largely affects women between 20 and 30. Women in their 40s and 50s have a stronger association for relapsing-remitting multiple sclerosis than men of similar ages.
Although Dr. Stoll says that men who are diagnosed with multiple sclerosis are more likely to have more severe symptoms and worser disease progression.
Symptoms of multiple sclerosis
Multiple sclerosis symptoms vary from person to person, and how the disease affects your body depends on what areas of the brain and spinal cord have a severe loss of myelin. Some symptoms, such as vision, may appear suddenly and worsen in a day or two. Meanwhile, you might experience progressive sensory loss in a limb that could make it difficult to walk or grip objects.
Neurologists say these are a sample of symptoms that you might see in someone with multiple sclerosis:
Loss of vision
Numbness or tingling sensation in multiple body parts
Sensory loss in the arm or leg
Limb weakness
Difficulty walking
Fatigue
Memory problems
Loss of focus or concentration
Problems with balance
Bladder issues
Dr. Picone says a person with lesions in their spinal cord from severe myelin loss may present with more severe movement issues, including:
Leg stiffness or weakness
Numbness around the waist
Sensation of pressure around the trunk
When to see a doctor
Dr. Picone says you should go to a doctor anytime you notice any change in your sensory or motor function.This could look like a tingling or weakness in balancing yourself upright or in your legs when you’re walking or exercising. She says a lot of her patients have reported feeling overheated being in hot weather.
“The best thing is to not ignore symptoms and get it evaluated even if you have numbness in the arm or leg,” explains Dr. Picone. “Many times in the past people wouldn’t think too much about it if it got better within the day and it could have been a pinched nerve or another problem, but it could also be a sign of MS.”
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