Multiple sclerosis, or MS, is a chronic condition affecting the neurons of the central nervous system. These neurons are wrapped in a substance called myelin, which insulates the neurons and facilitates the transmission of signals, explains the Multiple Sclerosis Foundation. In MS, the myelin in the brain and the spinal cord is destroyed. Without insulation, the nerves cannot transmit signals from the brain to the rest of the body, leading to a variety of symptoms. Doctors do not fully understand the causes of multiple sclerosis as of 2010, although some contributing factors have been identified.
Autoimmune Reactions
Damage caused to the myelin may be caused by autoimmune reactions, according to the Multiple Sclerosis Foundation. The immune system normally protects the body from infection by viruses and other microorganisms. When the immune system mistakenly attacks parts of a person's own body, this is called an autoimmune reaction. For unknown reasons, in people with multiple sclerosis, doctors suspect that the immune system mistakenly attacks the myelin coating of the neurons in the brain and the spinal cord.
Environmental Factors
Cases of multiple sclerosis are most prevalent in areas of the world that are farther away from the equator, especially northern Europe and North America, reports MedlinePlus. This clustering of disease cases suggests that some environmental factor may contribute to the onset of multiple sclerosis. Scientists have investigated numerous factors, such as diet, water or soil contaminants, and industrial toxins, but no conclusive links to multiple sclerosis have been identified as of 2010, according to the Multiple Sclerosis Foundation.
Infectious Agents
Many scientists suspect that the autoimmune reaction to myelin may be triggered by an infection with a virus, bacteria or other infectious agent, explains an article published in the March 2005 issue of "The Lancet Neurology." Several microorganisms, including chlamydia, pneumonia, measles, Epstein-Barr virus, canine distemper and human herpes virus-6, have been extensively studied, but no conclusive link with multiple sclerosis has been found, according to the Multiple Sclerosis Foundation.
Genetic Factors
Although multiple sclerosis is not a hereditary disease, meaning it is not always passed from parents to children, certain genetic factors appear to increase the risk of developing the disease, according to the University of Maryland Medical Center. For example, genes have been identified that are more common in families with more than one affected person. Doctors theorize that certain genes may make a person more likely to develop an autoimmune reaction to some environmental factor, reports the Multiple Sclerosis Foundation. These findings paint a picture of a complex interplay between genes and the environment in the causes of multiple sclerosis.
