Multiple Sclerosis Ms Causes

Multiple sclerosis is a result of the immune system’s attack on the central nervous system, resulting in a damaged myelin sheath. The exact cause of this abnormal response.

Scientists have been researching the cause and, while it has not yet been discovered, most agree that several factors are likely involved, including genetics, gender and viral infections.

Genetics and the Immune System

Genetics play a role in many types of autoimmune diseases. Researchers believe genetics may contribute to immune system changes that cause multiple sclerosis, but they do not believe that genetics is solely responsible for the disease.

Studies of twins indicate that if one twin has multiple sclerosis, the other twin has a higher than normal risk of developing MS. An identical twin without MS is 10 times more likely than a fraternal twin to develop multiple sclerosis. Note that identical twins have identical genetics, including immune system genetics.

However, many twins do not develop multiple sclerosis even if the sibling has the disease, suggesting that genetics alone does not cause multiple sclerosis. Although 15 to 20 percent of people with multiple sclerosis have a family history of the disease, the majority of cases appear sporadically, suggesting that genetics is only part of the cause.

Viral Infection, Disease and Multiple Sclerosis

Many multiple sclerosis researchers believe that the misbehavior of the immune system in MS is triggered by a combination of genetics and infection by a virus. Predispositions in individual genetics may allow a reaction to viral infections and result in changes to the immune system.

Possible viruses that may lead to multiple sclerosis in susceptible individuals include the human herpes simplex virus, measles, varicella and Epstein-Barr virus. However human herpes virus seems to be the most likely suspect. Human herpes virus has been found in multiple sclerosis plaques-hardened deposits that build up in the immune system as the disease progresses.

The herpes virus also has a preference for infecting nerve cells. Both the herpes virus and many cases of multiple sclerosis tend to cycle, that is they flare-up then go into periods of remission. This suggests a connection between the virus and the autoimmune disease.

Two theories suggest how genetics and infections by a virus may affect the immune system and cause multiple sclerosis.

  • One theory suggests that the immune system may damage the nervous system as it attempts to fight off a virus that is affecting the nerves.
  • The second theory suggests that genetics causes the immune system to become confused and to attack nerve cells instead of the virus itself. In MS, the immune system apparently attacks the myelin sheath because it has certain features resembling viral proteins.

Gender, Immune System Disorders and MS

Immune system diseases such as rheumatoid arthritis and systemic lupus erythematosus affect women more often than men. This is also true for multiple sclerosis. In fact, women are twice as likely as men to develop MS.

Other Potential Causes of Multiple Sclerosis

For reasons unknown, people who spend their childhood in temperate locations are more susceptible to multiple sclerosis than people who grow up in the tropics. Northern Europeans are more likely to develop the disease than other ethnic groups, although whether this is due to genetics or temperate geographic location is unclear.


Dangond, F. (updated 2005). Multiple sclerosis.

Fauci, A., Braunwald, E., Isselbacher, K., Wilson, J., Martin, J., Kasper, D., Hauser, S.