Multiple Sclerosis Causes

What causes MS? 

Multiple sclerosis (MS) is a complex condition that affects your central nervous system. The exact cause of multiple sclerosis isn’t known, but it happens when your immune system mistakenly attacks the myelin sheath in the central nervous system.

Myelin is a substance made of fat and protein that covers and protects nerve fibers. When the immune system attacks it, it results in inflammation and later scar tissue formation. This scar tissue is called sclerosis and the areas with scar tissue are called lesions or plaques.

This damage means your nerves can’t pass electrical signals to and from the brain like they should. Eventually, the nerve fibers may have permanent damage.

Your T cells and B cells in your immune system play a role in MS.

• T cells: These cells get activated in a part of the immune system called the lymph system. They enter the central nervous system through your blood vessels and trigger inflammation that damages the nerve fibers and myelin. Some T cells are supposed to stop inflammation, but in MS they don’t work correctly. Other types of T cells can directly destroy cells.
• B cells: T cells activate B cells, which work with T cells to produce antibodies. Antibodies normally fight infections, but with MS they damage the central nervous system.

Researchers believe MS comes from a combination of immune system malfunction, genetic issues and environmental exposures. They are studying these factors to try to find out exactly what causes MS. Knowing the cause can uncover better treatments and may eventually lead to a cure and ways to prevent it.

Is MS genetic?

MS is not directly inherited but genetics may play a role. Your risk is slightly higher than average if a close relative like a parent or sibling has the condition. But MS is not passed down predictably like some other genetic conditions.

Instead, having certain genes may make you more likely to develop MS, especially if you have other risk factors. Having a family history does not guarantee that you will develop the condition.

Risk factors for MS

Scientists have identified several environmental and lifestyle factors that may impact your risk for MS:

• Vitamin D: Low levels of this vitamin increase your MS risk. That could be because vitamin D plays a role in how your immune system works.
• Location: People who live in climates further from the equator, like the northern US, Canada, Europe, New Zealand and southeastern Australia, are more likely to be diagnosed. Exposure to sunlight helps your body produce vitamin D, so it’s possible that living in areas with less sunlight causes the lower levels of vitamin D that may be linked with MS.
• Infections: Some viruses, including the Epstein-Barr virus (EBV) which causes mononucleosis, may be linked to multiple sclerosis. Other viruses that may increase your risk of MS are human herpes virus-6 (HHV-6), canine distemper, chlamydia pneumonia and measles. Even though these viruses may be contagious, MS itself is not contagious.
• Autoimmune diseases: Your risk is slightly higher if you have another autoimmune condition like inflammatory bowel disease, pernicious anemia, psoriasis, thyroid disease or type 1 diabetes.
• Smoking: Smoking can increase your risk and using tobacco may also make MS get worse more quickly. 
• Age: MS is more common in people aged 20 to 50.
• Gender: MS is about two to three times more common in women than in men. This difference suggests that hormones and immune system differences may play a role.
• Race: Risk is highest in people with light skin and lowest in people with African, Asian or Native American backgrounds.
• Obesity: Being obese as a child, teenager or young adult may increase risk, especially in girls. Obesity may also cause inflammation that can make MS worse if you’re diagnosed.

Researchers have studied other factors that don’t show evidence of a link to MS. Allergies, pets, heavy metals and chemical solvents don’t appear to be connected with MS.

Even though there’s no way to predict whether you will develop MS, understanding these risk factors can help you make decisions about your health.

Do you have questions about the causes and risk factors for MS? Reach out to an expert at Banner Health for answers. 

Are you wondering how MS shows up in the body, or how it’s diagnosed? Learn about early symptoms, types of MS, and what to expect during testing, scans and exams.