How MS Attacks the Body
Multiple sclerosis (MS) is an autoimmune disorder where the immune system mistakenly perceives its own myelin (the sheath around the nerves) as an intruder and attacks it, as it would a virus or other foreign infectious agent. To understand how this harms the body, it helps to understand how nerves work.
A nerve can be seen by the naked eye, but it is made up of hundreds or even thousands of microscopic nerve fibers wrapped by connective tissue. Nerves conduct messages to and from the brain by way of electrical impulses.
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. (The same principle is used to improve electric wires by covering them with a plastic outer layer.)
How Does MS Destroy 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. It can also cause scarring (the “sclerosis” in the name “multiple sclerosis”). This causes electrical impulses to travel more slowly along the nerves resulting in deterioration of function in body processes such as vision, speech, walking, writing, and memory.