Multiple Sclerosis Risk Factors and Causes

The specific cause of MS is not fully understood. Symptoms are caused by an abnormal inflammatory attack on the nerves of the brain or spinal cord (called demyelination). This inflammatory response may be triggered by genetic, environmental, and viral factors that initiate the damage.

Demyelination is associated with an abnormal immune system response that causes a type of white blood cell (called T cells) to attack myelin. Damage to the myelin then leads to sclerosis of nerve fibers in the central nervous system (CNS). The CNS has the ability to repair some of the damage but may not be able to achieve complete restoration. Exacerbations and remissions (common in multiple sclerosis) result from the intermittent damage and restoration.

A higher incidence of MS in certain geographical areas, such as the northern United States, suggests that environmental factors may be involved, but none have been confirmed.

A specific viral risk factor has not been identified, but exposure to a virus that causes demyelination (especially prior to adolescence) may be a risk factor.

According to the National Institutes of Health (NIH) in February 2014, people with low levels of vitamin D may be at increased risk for multiple sclerosis. However, the NIH reports that it's unclear if low vitamin D levels are a cause or a consequence of MS.

In people with early-stage MS, studies show that those with higher vitamin D levels have better outcomes during 5-year follow-ups. More research is needed, but improving vitamin D levels may help in the early treatment of the condition.

Updated by Remedy Health Media

Publication Review By: Jean-Raphael Schneider, M.D.

Published: 31 Dec 1999

Last Modified: 25 Sep 2015