Multiple sclerosis (MS) is a disease that affects your brain and spinal cord, so before we can understand MS it’s best to learn a little about the layout of the nervous system.
Your brain and spinal cord make up what is known as the central nervous system, or CNS—which (simply put) is the part of your body that controls voluntary and involuntary actions. The CNS is made of many kinds of cells, but the two most important here are neurons and oligodendrocytes.
Neurons are the cells responsible for communicating parts of the body, creating a “highway” for information to travel across the body. This communication is usually transmitted through electrical signals or chemicals across the neurons’ branches.
Oligodendrocytes produce something called myelin, a substance that is mostly made of fat. Myelin wraps around parts on neurons, and by doing so acts similarly to insulation on wires: It helps keep the electrical and chemical signals from leaking outside the “wire”. If mass leakage were to occur, the communication between neurons would either become very slow, or would stop happening at all—like how a wire without insulation would short-circuit an electronic device.
In MS, this is actually what happens: Something destroys the oligodendrocytes, therefore stripping the neurons of their insulation. However, the disease sometimes progresses beyond removing the myelin—the attacking substance also damages the “wires” beneath, crippling communication between neurons even further.
What this means for the person with MS is that, depending on where in the brain the attacks occur, deficits will arise. For example, losing myelin around the optic nerve harms vision, while losing it in your cerebellum harms balance and coordination. MS patients can recover from these changes, but often they are permanent.
According to the NationalMSSociety, Other symptoms include: fatigue, walking difficulties, spasticity (stiffness and muscle spasms), weakness, dizziness and vertigo, bladder problems, bowel problems, pain, cognitive changes (like the ability to remember information and problem-solve), emotional changes, and depression.
These symptoms vary widely amongst patients, and come on in four different types of patterns: relapsing-remitting MS (RRMS), where there are flare-ups followed by recovery periods followed by even worse flare-ups; secondary-progressive MS (SPMS), in which people with RRMS stop the cycle of relapse-recovery and begin to steadily grow worse; primary-progressive MS (PPMS), where the disease progresses steadily from the beginning without relapses and remissions; and progressive-relapsing MS (PRMS), in which the other types are combined.
What causes MS?
Nobody knows for sure at this point. The primary perpetrator is thought to be the immune system: It incorrectly recognizes something in the myelin and nerve cells as a foreign invader, and attacks them. Or in other words, your body’s defense systems try to protect you from harm, and end up harming you in the process—also known as an autoimmune disease.
But what would trigger such a response? Is it genes? Or is it environmental?
Genetics certainly play a role in MS. The people most likely to develop MS are Caucasian women of northern European descent, and having a close relative with the disease ups your personal likelihood from 0.1% (the general population) to around 5%.
There are some other risk factors involved in developing MS. For example, smoking has been found to increase a person’s risk of developing the disease, and is known to make it progress more quickly and severely. (Thankfully, it was also found that quitting smoking either before or during development of MS slows disease progression.)
Further, scientists have found that MS likelihood varies by how far you live from the equator. The closer you are, the less likely you and your descendants are to develop the disease—a relationship which holds true for young people (<15 years old) who move either closer or farther away. Scientists believe it has to do with vitamin D exposure, because those who live closer to the equator generally receive more vitamin D from sunlight.
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