Multiple Sclerosis Home > Multiple Sclerosis Causes
What causes multiple sclerosis is still under investigation. Many scientists believe that the disease is an autoimmune disorder, meaning that the body mistakenly attacks part of itself. Genetic and environmental factors may contribute to the development of multiple sclerosis, but more research is needed before we will know for sure.
The cause of multiple sclerosis is still not known. For reasons not yet understood, the fatty substance called myelin (which covers nerve fibers) is damaged in random areas. The areas of damage are known as plaques. Myelin normally insulates entire nerve fibers. It helps nerve messages to be quickly and properly conducted to and from the brain. The symptoms of multiple sclerosis depend on where these plaques occur in the central nervous system.
Currently, most scientists believe that the loss of myelin is caused by an autoimmune process. This means that the body mistakenly reacts to some part of itself as though it was a foreign invader and attacks it. In the case of multiple sclerosis, the body destroys areas of its own myelin.
In addition to a possible autoimmune process, increasing scientific evidence suggests that genetics may play a role in determining a person's susceptibility to multiple sclerosis. Some populations, such as Gypsies, Eskimos, and Bantus, never get multiple sclerosis. Native Indians of North and South America, the Japanese, and other Asian populations have low incidence rates. It is unclear whether this is due mostly to genetic or environmental factors.
In the population at large, the chance of developing multiple sclerosis is less than a tenth of 1 percent. However, if one person in a family has multiple sclerosis, that person's first-degree relatives -- parents, children, and siblings -- have a 1 to 3 percent chance of getting the disease.