Multiple Sclerosis Causes

While the cause of Multiple Sclerosis (MS) is still not known, scientists believe that the interaction of several different factors —such as environmental or genetics factors— may be involved in the development of the disease.

What causes MS?

Multiple Sclerosis causes are unknown; however evidence suggests that the condition may result from a combination of genetics and environmental factors:

Environmental factors

Multiple Sclerosis occurs more frequently in areas that are farther from the equator. Scientists studying disease patterns are exploring if variations in geography (sunlight duration, changes in temperature and humidity, etc.), demographics (age, gender, ethnicity, migration patterns, etc.), diet, infection causes, exposure to environmental toxins may cause or exacerbate MS [1-2].

So far, no specific environmental factor has been proven to trigger the disease; it is likely caused by several factors.

There is growing evidence that the more sunlight exposure we have, and consequently the higher levels of naturally-produced vitamin D (which is thought to help immune function),  the lower MS risk [1-2].

Population migration studies support the notion that exposure to some environmental agent before puberty may predispose a person to develop Multiple Sclerosis later on. As such, people born in a MS high-risk area seem to acquire a lower risk if they move to an area with a lower risk before the age of 15 [1-2].

Studies have shown that smoking increments the risk of developing MS and correlates with more severe condition and faster disease progression [1-2]. Moreover, exposure to other toxic substances, like solvents or heavy metals, has been associated with MS development, but without reaching clear conclusions [3].
It has also been reported that too much salt may prompt the immune system causing autoimmune diseases [4-5].

Finally, even though infections have been often mentioned by doctors and researchers as a potential Multiple Sclerosis cause, this theory has not been scientifically proved [1-2].

Is MS hereditary? Genetic Factors

Although MS is not hereditary, people having a first-degree relative, such as a sibling or parent, with the disease have a higher risk of developing the condition. In fact, certain genes appear more frequently in populations with increased rates of MS and common genetic factors have also been found in some families with more than one person suffering the disease. For this reason, researchers speculate that predisposition to develop MS is influenced by genetic factors [1, 6-8].

References

1. In: http://www.nationalmssociety.org/What-is-MS. Accessed 25/01/2017.
2. O’Gorman C, Lucas R, Taylor B. Environmental Risk Factors for Multiple Sclerosis: A Review with a Focus on Molecular Mechanisms. Int J Mol Sci. 2012; 13(9):11718-11752.

3. Napier MD, Poole C, Satten GA, Ashley-Koch A, Marrie RA, Williamson DM. Heavy metals, organic solvents and multiple sclerosis: an exploratory look at gene-environment interactions. Arch Environ Occup Health. 2016; 711:26-34.
4. Hucke S, Wiendl H, Klotz L. Implications of dietary salt intake for multiple sclerosis pathogenesis. Mult Scler. 2016; 22(2):133-9.
5. Krementsov DN, Case LK, Hickey WF, Teuscher C. Exacerbation of autoimmune neuroinflammation by dietary sodium is genetically controlled and sex specific. The FASEB Journal. 2015; 29(8): 3446-3457.
6. Dyment DA, Ebers GC, Sadovnick AD. Genetics of multiple sclerosis. Lancet Neurol. 2004; 3(2):104-10
7. Hoppenbrouwers IA, Hintzen RQ. Genetics of multiple sclerosis. Biochim Biophys Acta. 2011; 1812(2):194-201.
8. Gourraud PA, Harbo HF, Hauser SL, Baranzini SE. The genetics of multiple sclerosis: an up-to-date review. Immunol Rev. 2012; 248(1): 87-103.
9. Muñoz-Culla M, Irizar H, Otaegui D. The genetics of multiple sclerosis: review of current and emerging candidates. Appl Clin Genet. 2013; 6: 63-73.

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Disclaimer

This general information is not intended to diagnose any medical condition or to replace your healthcare professional. You should consult with your health care professional for specific advice relating to your medical questions or condition. Only your practitioner can completely and appropriately assess your situation and make conclusive decisions regarding your care.