Epidemiology
MS is the most common chronic disease of the CNS in young adults. It affects an estimated 1.1–2.5 million people worldwide,1 of which 300,000 are in the US and 390,000 are in Europe.2
The disease occurs to some extent in all races, but it is most common among Caucasians and relatively rare in Asians or people of African origin. In crude terms, incidence and prevalence tend to increase with distance from the equator, but this relationship is a complex one that appears to be influenced by both geographical and genetic factors.3-5 In the temperate zones of Northern Europe, North America and Australasia, rates of approximately 100 per 100,000 population are recorded, reaching a peak of 300 per 100,000 in the Orkney and Shetland Islands, Scotland. In most of Asia and Africa, however, the prevalence is much lower — in the order of five per 100,000.6 It is believed that environmental factors may play a significant role in the onset of this disease. There is increasing evidence that vitamin D deficiency may be linked to the development of MS.7,8
MS affects roughly twice as many women as men, and tends to strike people while they are in the prime of life, often interrupting or even terminating their careers. Most cases are diagnosed between the ages of 20 and 40 when many people already have young children or are thinking of starting a family, with the most common age of onset falling between 31 and 33.6 MS is rarely diagnosed in children or in the elderly.
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3. Ferguson B, Matyszak MK, Esiri MM, et al. Axonal damage in acute multiple sclerosis lesions. Brain 1997; 120(Pt 3): 393-9.
4. Trapp BD, Peterson J, Ransohoff RM, et al. Axonal transection in the lesions of multiple sclerosis. N Engl J Med 1998; 338(5): 278-85.
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6. Steinmann L. Multiple sclerosis: a coordinated immunological attack against myelin in the central nervous system. Cell 1996; 85: 299-302.
7. Hohlfeld R. Biotechnological agents for the immunotherapy of multiple sclerosis. Principles, problems and perspectives. Brain 1997; 120: 865-916.
8. Wekerle H, Linington C, Lassmann H, et al. Cellular immune reactivity within the CNS. Trends Neurosci 1986; 9: 271-7.
