Cause of Multiple Sclerosis

The exact cause of multiple sclerosis is not well understood. What is fairly well accepted is that the damage to the myelin sheath, the "insulation" of nerve fibers, which characterizes MS and causes its primary symptoms, is caused by an autoimmune (against your own body tissues) attack on the myelin producing cells, called oligodendrocytes. It is unclear what initiates this inflammatory reaction, but the immune system, which should usually be able to tell "self" from "non-self", gets confused and attacks the myelin sheath in the central nervous system. Normally the immune system is important for fighting disease, fighting off invaders (bacteria, viruses, fungi, etc.), getting rid of foreign substances and abnormal cells. There are several types of autoimmune diseases and for most the underlying cause is not well understood. Likely, the underlying etiology that leads to the disease is multifactorial, resulting from some combination of environmental and genetic factors.

Environmental Factors

An interesting finding in the prevalence of multiple sclerosis is that it occurs more frequently in parts of the world which are further from the equator. It is quite common in northern Europe, in Scotland and the Scandinavian countries. However, if people born in these areas move to areas with lower risk (closer to the equator) their risk of developing the disease drops to about that of others. This implies that some environmental factor in higher latitudes may play a part in the underlying cause of multiple sclerosis. The details of this environmental influence are not well understood.

Genetic Factors

People with close relatives with MS are at higher risk for MS. Therefore it is assumed that there are some genetic factors which help predispose to the disease, although this does not seem to be the only cause. It is likely that any such genetic predisposition is related to multiple genes as no single gene abnormality has been associated with the disease.

Other Factors

Researchers have long hypothesized that some virus could be linked to MS, perhaps setting off the autoimmune attack. However, this has not been proven and no virus has been consistently to be associated with MS. There is also some evidence that hormone activity, particularly the sex hormones, may be associated with the disease; but again the details of this association are not clear.

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Important Note: This site is not intended to offer medical advice. Every patient is different, and only your personal physician can help to counsel you about what is best for your situation. What we offer is general reference information about various disorders and treatments for your education.

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