Multiple sclerosis (MS) is a progressive, neurological disease that can affect the central nervous system (CNS). Millions of nerve cells in the brain send signals throughout the body to control movement, sensation, memory, cognition, and speech. Every time you take a step, blink, or move your arm, your CNS is at work.
Nerve cells communicate by sending electrical signals via nerve fibers. A layer called the myelin sheath covers and protects these fibers. It ensures that each nerve cell properly reaches its intended target. In people with MS, immune cells mistakenly attack and damage the myelin sheath. This damage results in the disruption of nerve signals.
Damaged nerve signals can cause debilitating symptoms in a person with MS, including:
- walking and coordination problems
- muscle weakness
- vision problems
MS affects everyone differently. The severity of the disease and the types of symptoms vary from person to person. The exact cause of MS is unknown. However, scientists believe that four factors may play a role in the development of the disease.
MS is considered an immune-mediated disease. That is, the immune system malfunctions and attacks the CNS. Researchers know that the myelin sheath is directly affected, but don’t know what triggers the immune system to attack the myelin.
Research about which immune cells are responsible for the attack is ongoing. Scientists are seeking to uncover what causes these cells to attack. They’re also searching for methods to control or stop the progression of the disease.
Several genes are believed to play a role in MS. Your chance of developing MS is slightly higher if a close relative, such as a parent or sibling, has the disease. According to the Multiple Sclerosis Foundation (MSF), if one parent has MS, the risk of their children getting the disease is estimated between two and five percent.
Scientists believe that people with MS are born with a genetic susceptibility to react to certain (unknown) environmental agents. An autoimmune response is triggered when they encounter these agents.
Epidemiologists have seen an increased pattern of MS cases in countries located farthest from the equator. This correlation causes some to believe that vitamin D may play a role.
Vitamin D benefits the function of the immune system. People who live near the equator are exposed to more sunlight. As a result, their bodies produce more vitamin D.
The longer your skin is exposed to sunlight, the more your body naturally produces the vitamin. Since MS is considered an immune-mediated disease, vitamin D and sunlight exposure may be linked.
Researchers are considering the possibility that viruses and bacteria may cause MS. Viruses are known to cause inflammation and a breakdown of myelin (called demyelination). Therefore, it’s possible that a virus will trigger MS.
Several viruses and bacteria are being investigated to determine if they’re involved in the development of MS. These include:
- human herpes virus-6
In addition to genetics, the environment, infections, and the immune system, other risk factors may increase your chances of developing MS. For example:
There have been many theories on what causes MS. Many have been proven false by scientists. According to the National Multiple Sclerosis Society, the following theories are false:
- having a pet: Canine distemper, a virus carried by dogs, has been suggested a cause of MS. Research has found no connection between the two.
- exposure to heavy metals: Poisoning from metals such as lead and mercury can be harmful, but exposure to these metals doesn’t cause MS.
- physical trauma