Causes of Multiple Sclerosis

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We still have much to learn about what triggers the development of MS. As far as we know, it doesn’t result from a single cause.  Instead, it seems that both your genes and certain factors in the environment contribute to your risk of getting MS.1

Family studies have shown that parents, brothers and sisters, and children of people with MS are more likely to have MS. This family association tells us that genetic make-up leads some people to be more susceptible to MS than others, but it is not as simple as a single gene causing the disease.1

Certain environmental factors also seem to be involved. One is a common virus called the Epstein-Barr virus or EBV.1,2 It is important to remember that most people who get an EBV infection remain healthy. However, there does seem to be a connection since more than 99% of people with MS have been infected with EBV at some stage, and EBV has been found in MS lesions in the CNS.1,2

Smoking may also be a risk factor for MS.  A recent study showed that people who had smoked had about a 50% greater risk of developing MS than those who had never smoked.1 Earlier studies similarly show that the more you smoke, the greater your risk of developing the disease.1

Where you live in the world also has a strong influence on how likely you are to get MS.  Generally speaking, the farther away you are from the equator (increasing latitude), the greater your risk of developing the disease.3 Recently, low vitamin D levels have been linked to developing MS, which might help explain this geographical effect.1,2

1. Ramagopalan SV, Dobson R, Meier UC, Giovannoni G. Multiple sclerosis: risk factors, prodromes, and potential causal pathways. Lancet Neurol. 2010;9:727-739.
2. Bagert BA. Epstein-Barr virus in multiple sclerosis. Curr Neurol Neurosci. 2009;9:405-410.
3. Compston A, Coles A. Multiple sclerosis. Lancet. 2008;372:1502-1517.