Multiple sclerosis is an autoimmune disease in which the body's immune system attacks its own central nervous system . In MS, the immune system attacks and damages or destroys myelin, a substance that surrounds and insulates the nerves. The myelin destruction causes a distortion or interruption in nerve impulses traveling to and from the brain. This can result in a wide variety of symptoms.Multiple sclerosis is estimated to affect 2.8 million people worldwide.
Although MS is more common in women than men overall, one form of the disease contradicts this pattern. People with primary progressive MS are about as likely to be male as female. .People who smoke are more likely to develop MS, and to develop it more severely and with a faster progression. MS is more prevalent among Caucasians than other ethnicities. MS is believed to have a genetic component as people with a first-degree relative with the disease have a higher incidence than the general population.We don't know exactly what causes multiple sclerosis, but it is believed to be some combination of immunologic, environmental, infectious, and/or genetic factors. Some theories have been proposed, though there is not enough evidence to establish any one cause.
Often the nerve fibers that make up a nerve are all individually wrapped in myelin, a protective sheath that causes electric impulses to conduct down the nerve much faster than fibers that lack myelin. In multiple sclerosis, the immune system's T cells attack the myelin sheath. By attacking myelin, the immune system in a person with MS causes inflammation and degeneration of the myelin that can lead to demyelination, or stripping of the myelin covering of the nerves.