The cause of multiple sclerosis, or MS, is unknown as of 2015, according to the National Multiple Sclerosis Society. Scientists believe immunologic, environmental, genetic and infectious factors may play a role in the development of the disease.
An abnormal immune-mediated response breaks down the myelin that protects the nerve fibers in the central nervous system causing multiple sclerosis to develop, explains the National Multiple Sclerosis Society. Research is underway to determine what triggers this process, how it operates and how to slow or prevent it.
Because people are more likely to develop MS if they have close relatives with the disease, researchers believe people are born with a genetic susceptibility to contracting the disease, and certain environmental factors trigger the autoimmune response, states Healthline. Caucasians of northern European descent have the highest risk of developing the disease, says Mayo Clinic.
Researchers theorize that lower levels of vitamin D in the body may affect the development of MS, reports Healthline. Vitamin D plays an important role in proper immune system function, and the body manufactures the vitamin when exposed to the sun. People living farther from the equator are more likely to develop MS, which leads researchers to suspect a link exists between vitamin D levels in the body and the development of MS.
Viruses and bacteria, such as measles, human herpes virus-6 and Epstein-Barr, may cause MS to develop, adds Healthline. Scientists know that viruses cause inflammation and break down myelin, but no proof exists to prove any of them trigger MS, states the National Multiple Sclerosis Society.