Thursday, October 11, 2012

Risk Factors for MS

Julie Stachowiak, PhD
Writer, ms.about.com

 
After the "What next?" and the "What is going to happen to me?" type of questions that typically follow diagnosis, eventually most of us living with MS get around to pondering "Why did this happen to me?" We want to know if it was something we did or something that we were exposed to that may have led to us developing MS.

Why people develop MS is still a mystery to researchers. We do know that a variety of risk factors combine to create the "perfect storm" in certain individuals that leads to development of MS.

Two theoretical risk factors that have pretty solid evidence behind them are vitamin D insufficiency and exposure to certain infections.

The EnvIMS study is a large multinational case-control study that looked at people in Italy and Norway. It included 733 people with MS and 1438 controls (people without MS) from Italy and 959 people with MS and 1718 controls from Norway. Researchers collected data on childhood and adolescent sun exposure (sun exposure is necessary for vitamin D production) and sunscreen use by using a self-administered questionnaire. Here is what they found:
  • In both Italy and Norway, there was a significant association between less sun exposure and developing MS. 
  • In Norway, the association between low exposure to sunlight and MS was strongest in people who reported the lowest amount of sun exposure in the summer between the ages of 16 and 18, while in Italy, the people who reported the least summer sun exposure between the ages of 0 and 5 were the almost twice as likely to have MS. 
  • Interestingly, people who had the highest use of sunscreen in early childhood (0 to 6 years) in Norway were also more likely to have MS.

These findings indicate that there may be an important age variation in sun exposure in relation to MS risk.

Another risk factor that seems to contribute to people's risk of developing MS is infection. While it is very unlikely that infections directly cause MS, it does appear that certain infections may make certain people more likely to develop MS. For instance, Epstein-Barr virus (the virus that causes mononucleosis) increases a person's risk of developing MS by two- or three-fold.

One theory involves certain viruses, called human endogenous retroviridae (HERV). Humans were infected with these viruses millions of years ago and over the ages, the viral DNA became part of the human genome. It is postulated that, under certain conditions, some of these HERV may be able to form infectious virions, which could contribute to that kind of inflammation seen in MS. Research has shown that infections such as Epstein-Barr virus increase the production of HERV virions. It could be that the "right" combination of an infection and particular variant of HERV may lead to MS.

What does this research mean? There is not too much that we can do to prevent contracting Epstein-Barr virus (an estimated 96% of adults in the general population have been infected with EBV). However, sun exposure in early childhood and adolescence may be an important factor in preventing MS in later years. Outdoor activities for young people in all seasons are important for many reasons, and now it looks like lowering risk of MS can be added to the list of benefits. (It should be noted that no one is discouraging sensible use of sunscreen, which should absolutely be applied during the times when the sun is most intense, from 10:00 am to 2:00 pm, especially during the hot months.)

21 comments:

  1. I believe that the Parvo virus is what gave it the nudge with me....after experiencing it I began to notice my symptoms...and ironically I had some orthopaedic surgery done about 2 years ago, and since the bones weren't healing normally the Dr. did a blood test and found my vitamin D level to be very low...and just a side note I was diagnosed 10 years ago and the titer for Parvo is still of the charts...

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  2. I'm pretty sure they need to get an island in the caribbean designated for MS patients (like the old leprosy colonies) and send us all there for a minumum of 6 months of the year - probably cheaper than the MS drugs and medications and certainly the disability payments, could you offer my idea up at ECTRIMS and let me know how it is received? ;o) lmao

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    1. I am with you on this! Totally should be covered by insurance! :)

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  3. The caribbean would be way to hot and humid for me. I would want Alaska !

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  4. What does this research mean? Not much! If anything, I had too much sunlight as a young child and teenager yet I developed MS at age 23. I'm 43 and I have only met ONE person with Epstein-Barr... the math doesn't up... at all.

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  5. All though I have the Epstein Barr virus, I believe what set me over the edge was my double wamming of the measels when I was a child. I had the 2 week measels, and right after I developed the week measles, making me very ill for about 3 months.

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  6. I'm about in the same mindset as Peggy. When I was a kid, I went camping all the time, and had a LOT of sun exposure. Granted as I got into my teens, that exposure went down, but not by much. And here I am, diagnosed a few months before my 21st birthday. I've never been too healthy of a kid, but I don't remember ever being told I was low on vitamin D.

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  7. This fits for me. I grew up in New England, got tons of sun exposure in the summer through my early teens and had a mild case of mononucleosis at age 16. My 1st m.s. symptoms appeared post-pregnancy at age 36, and I'm now 47. So far I've been blessed with few relapses and overall good health. Stress aggravates my m.s., and worrying about how to pay for health insurance (I'm self-employed) causes stress.

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    1. Wow, this almost sounds like I wrote this comment myself! I grew up in New England as well, had a moderate case of mono at 16...and my first MS symptoms appeared post-pregnancy at 25. I'm also self employed and money/insurance stress definitely makes my MS worse!

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  8. I am another person that was exsposed to alot of sun from early childhood up until the last 5 years when it seems to flair my MS up on really hot days. I spend every summer between the beach and the swimming pool, horse back riding and ect. But in 2009 I was finally told I had MS. So this research doesn't really tell me a thing about about why I have Secodary Progressive MS...

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  9. My symptoms came on approximately two months after I had the shingles. Nobody in my family recalls me ever having the chicken pox and I do not recall having it but out of nowhere in the Fall of 2010 I got shingles, took anti-virals and everything cleared up that October. In December of 2010, my first MS symptoms started. My vitamin D levels have never been documented lower than 31 (which is the low end of normal, but still). It was said that I likely developed shingles from the stress of grad school, teaching, and my job as a fitness instructor but doctor's pretty much ignored it after it went away just like my MS symptoms were ignored until had an MRI looking for a bulging disc in my neck to explain numbness and BAM lesions. I do believe that my shingles had something to do with it but I'm not sure about the Vit. D

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  10. I grew up in northern PA. Being fair skinned, if I was in the sun, my mom made sure I was "lubed up" with sun screen. When I was 15, I had mono rather bad, resulting in a hospital stay. Almost a year to the date, I had mono again, although not as severe that time. The doc was surprised to see I had it again, as I guess the thought was it was only something you got once. I was diagnosed with MS in December of 2010, after a years worth of various test and doctors. I was 43. Looking back, I'd say the tremors I was diagnosed with in 2002 was most likely the beginning.

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  11. The EBV fits for me (it does for a lot of people) but the lack of early exposure to sunlight doesn't. I was in the scouts and we were always outside. Hell, I spent whole summers camping. Is it, perhaps, going from a lot of sun to very little that may cause the problem?

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    1. I agree with your theory. I spent my childhood camping and working around horses. I wasn't diagnosed until I was 40 but I remember thinking through much of college that I was living life in a fog. I never had mono but had chicken pox at age 6.

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    2. I was just wondering that too. I was born in Hawaii, moved to Washington at age 3. Age 5 moved to the Bahamas for a couple years, moved back to Washington at age 7. Lived here ever since. Lots of sun in the tropics, not so much in the PNW.

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  12. I grew up in Alabama, was a total outdoor type kid and don't remember ever wearing sunscreen. HOWEVER, I did have a life threatening case of EBV in 1996, and my body has never felt "right" since then. I was diagnosed with MS in 2005..

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  13. Like many other posters here, I was diagnosed with a nasty case of mono at age 15 (short hospital visit as well). I grew up with plenty of sunshine, spent all summers at the swimming pool and winters skiing. However my family moved from Colorado to Seattle, WA when I was 16. So the part of the study about less sunshine in the summner between the ages of 16 and 18 fits me as well. Major stress junkie most of my adult life as well. Diagnosed with SPMS in early 40's.

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  14. I got a lot of sun expsoure as a child. I live in Australia and was young before the slip slop slap message became really prevelant. I was sunburnt a lot... and always very very tanned during summer. Even as a teenager I was very outdoorsy. I did have glandular fever (or mono) as a 14 or 15 year old. I started wearing sunscreen and a hat probably in my early 20's when the skin cancer message really hit home for me.... So maybe it's not sun exposure as kids that makes a difference, but really the way MS susceptible people make vitamin D... or make vitamin D after exposure to mono?? I find this research really interesting and that so many of us can say similar things in the face of alternative explanations by research. Maybe there are many ways of "contracting" MS.

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    1. I like your theory about how our bodies deal with Vit D after having mono. This makes more sense to me. I was a sun lover as a kid and young adult as well and got mono around age 15-16.

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  15. That fits me to a tee.
    When I was 17 or 18 yrs old, I spent a summer almost in darkness as I had a night job working from 11pm to 6am. I of course slept during the day missing therefore the summer sun. Living in Canada means also little sun outside of summer.
    Even more interesting I had contracted a virus about 10 years ago which doctors diagnosed as a mononucleosis.
    At 46 yrs old, I just got a diagnosis of PPMS. My symptoms really started about 4 years but it was only last year when the symptoms had become more serious therefor leading to the diagnosis.

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  16. I lived in the sun as a kid & young adult so much so that I now have to see a dermatologist regularly for skin checks. I did have mono in HS but so do a lot of people. I'm not sold on the Vit D theory.

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