Multiple sclerosis (MS) affects the central nervous system, causing problems with vision and movement. Genetic, immunological, and environmental factors may contribute to developing MS.

MS occurs when the immune system attacks myelin, a protein that surrounds and insulates nerve fibers. Myelin helps nerve signals travel accurately and quickly along nerve fibers.

When MS damages myelin, nerve signals are interrupted, which can lead to coordination problems, vision loss, and pain.

While the precise causes of these changes to the immune system remain unclear, environmental and genetic risk factors and some viral infections may play a role.

Below, we explore the possible causes of MS, as well as its symptoms and treatments.

MRI scan of a brainShare on Pinterest
sudok1/Getty Images

The immune system is a complicated network that protects the body from pathogens, such as viruses and bacteria. Various health problems result from the immune system behaving in an unusual way and attacking healthy tissue.

People with MS experience characteristic immune responses that damage different parts of the central nervous system, including the brain and spinal cord.

In someone with MS, activated T cells, a type of white blood cell, move through blood vessels and into the central nervous system, releasing chemicals that cause inflammation and damage myelin, nerve fibers, and other nerve cells.

These T cells also activate B cells, which create antibodies and cause further damage to the central nervous system. MS also limits the functioning of T regulatory cells, which usually keep inflammation at bay.

The resulting increase in inflammation mostly damages myelin, a fatty protein surrounding nerve fibers. Myelin helps nerve signals travel along nerve fibers called axons.

Over time, the inflammatory responses that characterize MS cause major damage to myelin and axons in the central nervous system. Depending on the extent of the damage and where it occurs, different symptoms emerge.

In addition, MS damages cell bodies in the brain. As the disease progresses, the outer layer of the brain, called the cerebral cortex, begins to shrink.

The specific triggers of the MS immune response remain unclear. They may include viral infections, environmental factors, genetic factors, or a combination.

The National Multiple Sclerosis Society describe several environmental factors that could increase the risk of MS, including:

  • Geography: MS is more common in countries farther from the equator. If a person moves from a high- to a low-risk country before the age of 15, the likelihood of their developing MS decreases.
  • Vitamin D: Unusually low levels of vitamin D could increase the risk of MS. Sun exposure in countries close to the equator may help reduce the risk.
  • Smoking: Smoking increases the risk of MS, accelerates its progression, and causes more severe symptoms. Quitting can reduce the risk of smoking contributing to the disease.
  • Obesity: Childhood and adolescent obesity increase the risk of developing MS later in life, particularly for females.

Several viral infections could trigger MS, and researchers have found that the Epstein-Barr virus (EBV) is most linked to the disease.

EBV is part of the herpes virus family, and it is one of the most common viruses worldwide. It causes infectious mononucleosis, which is sometimes called “mono” or glandular fever.

When adults or adolescents contract an EBV infection, they tend to have a greater immune response, compared with younger children.

Research indicates that an exaggerated immune response to EBV, rather than the virus itself, may be what increases the risk of MS. Fully understanding the link between the virus and MS will require further studies.

People with MS are more likely than others to have at least one family member with the disease.

Several clusters of genes that influence how the immune system works may increase the risk of MS. If someone inherits these genes, they could have a higher risk, compared with the general population.

However, MS itself is not hereditary. A parent with MS does not pass it to their offspring.

MS affects the central nervous system and can cause a wide range of symptoms. Some early symptoms of MS include:

  • unusual sensations, such as prickling or pins and needles
  • pain
  • blurred vision
  • difficulty distinguishing between red and green
  • vision loss
  • difficulty walking

Learn more about early signs and symptoms of MS here.

As the disease progresses, it can damage different areas of the central nervous system, causing:

  • coordination problems
  • tiredness
  • difficulty thinking
  • muscle weakness
  • muscle spasms or stiffness
  • speech problems
  • tremors
  • dizziness
  • numbness
  • hearing loss
  • difficulty with bowel and bladder control
  • sexual dysfunction
  • depression

MS symptoms are “broad,” overlapping with those of several other conditions. A doctor needs to perform a range of tests, including MRI and bloodwork, to rule out other issues before they can diagnose MS.

A doctor who suspects MS attempts to identify at least two distinct areas of damage to the central nervous system at different points in time. These areas may include the spinal cord, brain, or optic nerves. Once they identify this damage and rule out other conditions, they may diagnose MS.

As part of the testing, the doctor may request a lumbar puncture. This involves inserting a needle into the lower part of the spine to extract cerebrospinal fluid for analysis.

They may also look for specific biomarkers as a way of measuring electrical signals in the central nervous system, as these signals are disrupted in people with MS.

There is currently no cure for MS, but a range of treatments can help manage the symptoms and reduce disability.

For new symptoms, or if the doctor observes new damage during testing, they may recommend disease-modifying therapies as a part of a treatment plan.

MS symptoms can flare up and recede. To treat or prevent flare-ups, the doctor may recommend techniques for managing stress and avoiding overheating.

Other techniques, such as physical therapy and exercises that help with maintaining a correct gait, may reduce the risk of a fall and injury.

MS is a lifelong condition that typically worsens over time. Complications range from mild to severe and depend on which parts of the central nervous system are affected.

Receiving ongoing, adjusted treatments can help people with MS manage the symptoms and delay the onset of disability.

MS occurs when the immune system attacks myelin and other parts of the central nervous system. The triggers for this remain unclear.

Environmental and genetic factors and viral infections may each increase the risk of MS. A combination of these factors is more likely responsible.

People with MS typically require ongoing treatment to manage the symptoms and slow the progression to prevent disability. The symptoms may be mild to severe, and rates of progression vary. MS is rarely fatal.