Who gets MS?It is estimated that up to 1.2 million people have MS worldwide. Anybody can get MS, whoever they are, and wherever they live.
Interestingly, global distribution patterns suggest that both hereditary and environmental factors could play a part in people contracting the disease. For example, MS is most prevalent in northern Europe, North America, South-East Australia and New Zealand. It is least observed in tropical and sub-tropical regions.
Multiple Sclerosis occurs more frequently in women than in men, and typically develops between the ages of 20 and 40. The average age of onset is 31-33. Multiple Sclerosis is rarely diagnosed in children or the elderly. However, In fact, studies have suggested that the risk of developing of MS is established early in life. For example, an individual who was born in a low risk area, such as Asia, and moves before the age of 15 to a high-risk region such as Northern Europe, may be at an increased risk of developing the disease1,2,. Race
MS occurs at higher rates in Caucasian populations than in any other ethnic group.
Age and MS
MS can occur at any age, although the average age at diagnosis is approximately age 30. Less than 4% of affected individuals develop the disease during childhood. In childhood, Relapsing-remitting Multiple Sclerosis is the most common form of disease, with a predominance of sensory symptoms and a higher frequency in females3.
Gender and MS
Women are twice more likely to develop MS than men, with the only exception being Primary-progressive MS, where there is an equal prevalence among men and women4. When present in males, MS tends to be more severe and often has a poorer prognosis5.
MS prevalence
MS is unevenly distributed throughout the world, and has been geographically described in three frequency zones6:
- High prevalence (>30 per 100,000) – large areas of Europeincluding Russia, Canada, northern USA, south-eastern Australia and New Zealand.
- Medium prevalence (5–30 per 100,000) – southern USA, most of Australia, South Africa, the southern Mediterranean basin, Siberia, Ukraine and some parts of Latin America.
- Low prevalence (<5 per 100,000) – large areas of Asia, Africaand northern South America.
The risk of developing MS changes when an individual migrates from a country of low incidence to one of high incidence and vice versa7. It is therefore thought that environmental factors may play a significant role in the onset of this disease, though no specific factors have been identified to date.
A link with MS prevalence has been established in countries furthest from the equator. MS occurs more frequently in Caucasian populations than in any other ethnic division, but even amongst Caucasians there is a distinct increased prevalence in countries or regions of increased northern latitude in the Northern Hemisphere and increased southern latitude in the Southern Hemisphere. Scotland, for example3, has a higher rate of MS prevalence than both Englandand Wales, perhaps due to its northern latitude. Additionally, as distinct areas of Scotland, such as the south east and Orkney and Shetland, appear to have amongst the highest rates of MS prevalence in the world, perhaps a genetic predisposition to MS in these specific areas may be of importance8.
View a chart detailing the worldwide prevalence of MS.
References
1. Dean G. : Annual incidence, prevalence and mortality rates of MS in white South African born and in white immigrants to South Africa. BMJ 1967;2:724-730. 2. Paty DW, Ebers GC (eds). Multiple Sclerosis. Philadelphia: FA Davis Company; 1998. 3. Duqette P, Murray TJ, Pleines J et al. Multiple sclerosis in childhood: Clinical profile in 125 patients. Journal of Paediatrics 1987;111:359-363 4. Cottrell DA, Kremenchutzky M, Rice GP et al. The natural history of Multiple Sclerosis: a geographically based study. 5. The clinical features and natural history of primary-progressive Multiple Sclerosis. Brain 1999; 122: 625―39. 5. Weinshenker BG, Rice GP, Noseworthy JH et al. The natural history of Multiple Sclerosis: a geographically6based study. 3. Multivariate analysis of predictive factors and models of outcome. Brain1991; 114: 1045―56. 6. Kurtzke JF. Multiple sclerosis in time and space – geographic clues to cause. J Neurovirol 2000; 6 (suppl 2): S134–40. 7. Dean G, Elian M. Age at immigration to England of Asian and Caribbeanimmigrants and the risk of developing Multiple Sclerosis. J Neurol Neurosurg Psychiatry 1997; 63: 565–8. Kurtzke JF. Multiple sclerosis in time and space – geographic clues to cause. J Neurovirol 2000; 6 (suppl 2): S134–40. 8. Rothwell PM, Charlton D. High incidence and prevalence of Multiple Sclerosis in Southeast Scotland: evidence of a genetic predisposition. J Neurol Neurosurg Psychiatry 1998; 64: 730―5. |
