Medicine is filled with researchers pouring long hours into the question of nature versus nurture. When they find answers, it is almost always “both”. Then the next question lies in how do the two interact. In multiple sclerosis two immune genetic markers, LA-DRB1*15 and HLA-A*02 have been long known to influence risk, the former increasing it and the latter decreasing it. Still statistics told them that the environment must play a major role in the disease as only a small portion of those with the HLA-DRB1*15 genetics developed MS.
A few articles provide insight into the environmental factors for this devastating disease which attacks and disables the immune system. First, Medscape Pediatrics online shared a summary from a poster presentation at the 35th Congress of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) 2019 (link below). Their research found an increase in MS 8 years after concussions in males during adolescence. The risk after concussion was nearly double versus those without a concussion event. The article also mentions an Annals of Neurology study from Sweden that showed having 2 concussions was an even greater risk.
Medscape also published a summary of another study linking common organic solvents to MS risk. In that study, they suggested that those with a family history of MS or known HLA DRB1*15 gene should avoid smoking and limit exposures to various solvents. The solvents mentioned include hydrocarbon compounds like those found in paint, varnishes, adhesives, dry cleaning and even some cosmetics. This did not mean that good genetics permits you to breathe in solvent vapors without harm. Even in those with favorable genetics, smoking and / or solvent exposure increased risk for MS. However, if you had unfavorable genetics, smoking and solvents could increase your risk 30 fold. One downside of this study was the problem of recall bias. They study looked at those with MS and asked them to report their past exposure to the solvents rather than having tested them directly for the solvents. This oversight could introduce unknown error into the final data.
From this last article, a few other cross references stood out. In one, EBV was linked to multiple sclerosis risk. In another, vitamin D levels were linked to MS risk. In yet another, sunlight exposure was linked to lower MS risk. In the last two, obesity was linked with MS risk. These articles are listed further below.
All in all, I re-emphasize the importance of nature and nurture interacting to produce disease risk for MS and for most of chronic illness. While congenital diseases of newborns are more likely genetics alone, the disease of adult life develop as an interplay of nature and nurture. This gives functional medicine types like myself hope that while genetics is rather fixed, we can guide our patients in modifying environmental exposures to lower the chances of diseases like MS. Nurturing the healthier more abundant life requires several ounces of prevention as well as curative therapies.
Medscape, Risk Nearly Doubles 15 Years Following Teen Concussion. https://www.medscape.com/viewarticle/918794
Annals of Neurology link: https://onlinelibrary.wiley.com/doi/epdf/10.1002/ana.25036?referrer_access_token=iB8WmCZjvqdIBRGEB5laEE4keas67K9QMdWULTWMo8MMY9mTvbd0KEGRCjLEXRHJFz2cPh3zFTH1G8HXzqe9jBt_dvlbwqjUTlb-F8vqROpA69Gm4gHAmPWjCXiHcdP1gc-nyQKGScIHt4WgWoDnew==
Medscape, Common Solvents Strongly Tied to MS Risk, https://www.medscape.com/viewarticle/898928
Annals of Neurology
Organic solvents and MS susceptibility. Anna Karin Hedström, Ola Hössjer, Michail Katsoulis, Ingrid Kockum, Tomas Olsson, Lars Alfredsson. Neurology Jul 2018, 91 (5) e455-e462; DOI: 10.1212/WNL.0000000000005906
Sundqvist E, Sundström P, Lindén M, et al. Epstein–Barr virus and multiple sclerosis: interaction with HLA. Genes Immun 2012;13:14–20.
Simon KC, Munger KL, Ascherio A. Vitamin D and multiple sclerosis: epidemiology, immunology, and genetics. Curr Opin Neurol 2012;25:246–251.
Bäärnhielm M, Hedström AK, Kockum I, et al. Sunlight is associated with decreased multiple sclerosis risk: no interaction with human leukocyte antigen-DRB1*15. Eur J Neurol 2012;19:955–962.
Munger KL, Chitnis T, Ascherio A. Body size and risk of MS in two cohorts of US women. Neurology 2009;73:1543–1550.
Hedström AK, Olsson T, Alfredsson L. High body mass index before age 20 is associated with increased risk for multiple sclerosis in both men and women. Mult Scler 2012;18:1334–1336.