Multiple sclerosis is a disease of the central nervous system. It's a mysterious illness that causes the body to attack a substance called myelin, which helps nerve fibers carry electrical impulses. As the body tries to repair itself, scar tissue is formed. This scar tissue, known as plaque, interferes with the flow of information nerves send - resulting in symptoms that range from lack of coordination to blurred vision, to difficulty with speech and even paralysis.
It affects young adults mostly - more women than men.
The exact cause of the disease is still unknown, although researchers suspect it involves both genetic factors and environmental exposures.