Friday, November 14, 2008
Environmental Factors in MS
I started to write a response to Merelyme's comment on my last post, but quickly realized it needed a post of its own. Her comment first: So people can get MS from environmental agents?
An environmental agent can be anything in the person's environment:an acquired virus, a chemical agent, an immunization, not enough sunlight, noisy neighbours, or a combination of those things. It is currently thought that a person's genetic make-up, coupled with an environmental factor is what triggers the auto immune response that we know as MS. For example: if you are born with MS genes and you are exposed to a certain virus as a child and you happen to live in the Northern hemisphere, then you get MS. However, if you don't have the genetic factor, then the virus and lack of sunlight do nothing more than leave you pale.
We don't know if this is how MS works, but it's a current theory. We also can't identify all the genetic factors involved. A few genes have been implicated, but nothing has been proven at this point and we haven't identified all the genes involved. It is a sometimes very complex disease because we don't know the whys and hows. But to put it simply, we have a weakness in our blood brain barrier (which may be genetic in nature or a result of environmental factors) that allows something into our CNS that shouldn't be there. The body's response to that "something", whether it's a virus or chemical we are exposed to, is to turn on itself, and eventually when abnormal body function is observed, the response is called MS.
Some researchers are working on the blood brain barrier, either to see why it's been weakened or to see if it can be strengthened. Some researchers are working on myelin repair and regeneration, and still others are looking at the complex chemical reactions that occur on the cellular level to reduce inflammation.
There is also some research into nutrition. Our food is what we would consider an environmental factor as well.
In answer to your question, at this point in time, no we don't "get" MS from the environment, at least not in the same way we get the flu or measles. The environment possibly contributes to our getting MS, but on its own the environment is not responsible (we think). Our environment is too big and too varied to pin it down at this point.
You can think of it this way. Let's say that an illness develops in all kinds of people around the world. They all live in different communities, some in China, some in Africa, some in North America. they all eat different food. Some have had measles and other childhood illnesses. Some haven't had even a case of the sniffles. But what they all have in common is they all have pet rabbits. So the logical conclusion is that they've all been infected with the illness by their rabbits. So researchers start examining the rabbits and discover a previously unobserved species of flea that only lives on rabbits. The rabbits scratch the flea bites and infected skin is shed into the air and is touched by the rabbit owners, who in turn develop the illness. Now the researchers can look at methods of eliminating the fleas, or treating the flea bites so the animals don't scratch and shed infected skin, or they can kill all the rabbits, thus eliminating the food source of the fleas causing the fleas to die off. But researchers also discover that some people who own rabbits that are infected with fleas don't get the illness. By examining those people, the researchers may be able to discover if these people have a natural immunity to the illness or perhaps an immune system better equipped to handle exposure to the infectious agent. Then they may be able to develop a vaccine or physical improvement to the humans' bodies to avoid the illness.
If you're still with me at this point, consider this: in the story of MS, we just haven't discovered what we all have in common. We're not all women. We're not all living in the extreme Northern or Southern hemispheres. We're not all of Northern European heritage. But we all have pet rabbits that are making us sick. We just don't know what our pet rabbit looks like.
hope this helps!
The picture at the top is from The Velveteen Rabbit.