Multiple Sclerosis has so far been found to be most prevalent among Caucasians, particularly those of Northern European ancestry. There are a number of studies showing that whites are most likely to get MS. Caucasians are twice as likely to suffer from MS as African-Americans. MS is also not commonly found in people of Asian, Indian, South American, and Native American descent, and particularly uncommon in people from the African sub-continent. There have also been studies that have found that there are certain ethnicities that seem to have a resistance to MS, these groups include American Inuit, the Lapps of Scandinavia, and the Maoris of New Zealand. In addition to MS being most common among Caucasians, it is also two to three times more likely to occur in white females. There are numerous studies that have been carried out to try and explain the epidemiology of multiple sclerosis. One thing the medical community has come to a consensus on is the geographical distribution of MS. It has been found that MS occurs mostly in regions away from the equator- the Northern United States, Canada, Northern Europe, Southern Australia, and New Zealand. (As shown in the map below)
There is some debate though, to what actually causes this distribution. Some believe it is climatic, others believe it is related to patterns of migration and ancestry, and still others believe it is related to socioeconomic issues that hinder awareness and diagnoses. The climatic factors are an example of medical ecology. One of these factors being studied is the relation of the amount of sun a person gets, and therefore their vitamin D levels, and the fact that the prevalence seems to occur in areas away from the equator. This is an intersection of health and environment, and one of the arguments backing this line of thought, is that African-Americans who live in these northern regions have a much higher rate of MS than Africans living on the sub-continent. The migration argument is an example of political ecology. Some researchers think that this distribution of MS backs the race or ethnicity theory because it follows the historical migration patterns of Northern Europeans- to North America, Australia, and New Zealand- in particular the patterns of the ancient Vikings and Scots. One backing of this theory is that Northern Ireland has a much higher prevalence of MS than the Irish Republic, and this area was historically, much more populated with those of Scottish descent. Lastly, is the social determinant of perhaps a lack of awareness about MS, this falls into cultural ecology. Some researchers believe this distribution of MS is an indicator of cultures that are not readily aware of MS and therefore lack the number of diagnoses found elsewhere, in more developed countries. I personally believe it is a combination of all these factors. There are probably ancestral components, as well as relationships between the patterns of migration found in the geographical areas with more prevalence. Also, there has been a lot of convincing research regarding the climatic and environmental effects on the onset and prevalence of MS, that I believe must be factored in, when discussing the patterns of multiple sclerosis.
1- Marrie, R. (2004). Environmental risk factors in multiple sclerosis aetiology. The Lancet Neurology, 3(12), 709-718. Retrieved from http://www.sciencedirect.com/science/article/pii/S1474442204009330
2- The Multiple Sclerosis Trust. http://www.mstrust.org.uk/information/publications/msexplained/who_gets_ms.jsp (Photo)
3- Compston, A. (2008). Multiple sclerosis. The Lancet, 372(9648), 1502-1517. Retrieved from http://www.sciencedirect.com/science/article/pii/S0140673608616207