What causes MS?
The nerves in the brain, spinal cord, and optic nerves are lined up in a well-organized pathway. All nerves function by sending electrical signals to each other. These signals send orders from the brain down to the spine and out to the muscles to produce movement. The electrical signals can also send messages in the other direction, from the skin, along the spine, and then up to the brain, to let you know that you are touching something hot or cold, sharp or soft, solid or liquid.
Let's take a tiny break from MS to talk about electrical wires. The electrical wires in a house are lined with a padded insulation to help the electricity travel quickly from one place to another in your house. The insulated coating also protects the wires and keeps the signals in the electrical wires, so the signals can keep traveling along the wires. If the wires didn’t have enough insulation, the electricity wouldn’t travel through the wire, and the wire would just be a useless piece of metal.
Nerves, like electrical wires, are also coated for insulation and protection. Nerves are coated with a special type of fat called myelin. The myelin protects the nerves and helps the electrical nerve signals travel quickly, without losing intensity.
In MS, some patches of myelin that normally coat the nerves are gone. This is called demyelination.
Demyelination = loss of myelin.
When there is demyelination, the electrical signals that travel from one nerve to the next can’t send the signal along the pathway because the message decreases in intensity.
People with MS can have patchy demyelination in the brain, spinal cord or optic nerve.
As a result, the electrical message that should travel along these nerves might not travel from the spine to the brain or from the brain to the spine. So, a person with MS might not be able to see out of one eye. Or, she might not be able to move her left arm. Or she might not feel anything touching her right foot. Depending on where the myelin patch defect occurs, the corresponding nerve can't send or receive signals anymore.
Why does demyelination occur?
This is truly a million dollar question. There are several working theories. This means that medical scientists are studying a few different ideas about why demyelination occurs.
One consistent finding is that areas of demyelination always have inflammation around them as if there is an ongoing infection. But so far, no one has been able to find a virus or a type of infection that affects the majority of people with MS.
Scientists suggest that a person with MS has an overactive immune system that attacks the person’s own myelin, destroying it. Some scientists propose that a virus attacks the myelin. There are theories suggesting that the myelin itself may be defective, and, therefore, cannot form properly. Recent research suggests that a vitamin D deficiency may contribute to the development of MS.
Interestingly, people who live in colder climates are more likely to develop MS than people who live in warm climates- even if they were born in a country with a warm climate.
All of these theories about the cause of MS are based on solid scientific research, but none of the explanations fully explains the cause of MS. The actual answer is still a bit of a mystery, and all of these theories will probably have something to do with finally explaining the source of MS.
Next: Improvement, Treatment, Diagnosis of MS