The age-range of risk of developing multiple sclerosis: Evidence from a migrant population in Australia

Abstract

The prevalence of multiple sclerosis in the Australian-born population in five different regions of Australia has a strong correlation with latitude, the disease becoming increasingly prevalent with increasing south latitude. In this study, the prevalence in the migrant population from the UK and Ireland (UKI) in the different regions also showed a significant correlation with latitude, but this relationship was strongly influenced by the high prevalence in Hobart. Except for Hobart, the prevalence in migrants was considerably less than that in their countries of origin. The prevalence of multiple sclerosis among those migrating before the age of 15 years from the high-risk UKI to lower-risk Australia was not significantly different to that among those migrating at or after that age, and this finding was confirmed in a case-control study which demonstrated little association between age at migration and risk of developing multiple sclerosis. These findings suggest that the risk from environmental factors in multiple sclerosis may operate over a period of many years and not only in childhood and early adult life.

IL-10 Signaling Is Essential for 1,25-Dihydroxyvitamin D3-Mediated Inhibition of Experimental Autoimmune Encephalomyelitis

“…Worldwide studies have attributed this gradient to a strong link between low sunlight exposure and high MS risk (2)(3)(4)(5). Because sunlight exposure produces vitamin D 3 (6), we hypothesized that the high MS risk with low sunlight exposure might reflect insufficient sunlight-catalyzed vitamin D 3 synthesis to support the immunoregulatory functions of the vitamin D 3 hormone, 1,25-dihydroxyvitamin D 3 (7).…”

Contribution of vitamin D insufficiency to the pathogenesis of multiple sclerosis

“…Accordingly, even if the simple encounter with EBV remains in the great majority of cases a banal infection without apparent deleterious long-term consequences, it could also, in some cases, be the first event triggering a long-lasting deleterious immunological cascade, worsened both by a late primo infection occurrence with symptomatic infectious mononucleosis and by the persistence of a high anti-EBNA1 level, [Gale and Martyn, 1995;Alonso and Hernan, 2008;Simpson et al 2011;Sloka et al 2011a], at a continental level [Kurtzke, 1995;Puggliatti et al, 2006], in large countries, such as the United States [Acheson et al 1960;Kurtzke et al 1985, Kurtzke, 2008, the former Soviet Union [Boiko et al 1995] and Australia [van der Mei et al 2001;Taylor et al 2010] and even in comparatively smaller countries, such as New Zealand [Taylor et al 2008] and France, at least in farmers [Vukusic et al 2007]. MS prevalence may change after migrations occurred during the second decade of life, with, for example, a beneficial effect for people who have migrated from a high-latitude region (with a high MS prevalence) to a sunnier, lower-latitude region (with a low MS prevalence) [Kurtzke et al 1985;Gale and Martyn, 1995;Hammond et al 2000;Munger, 2007a, 2007b;Handel et al 2010a;McDowell et al 2010;McLeod et al 2011]. It should be noted that a reverse migration, that is, from a lowlatitude region to a higher-latitude region, has less effect on MS prevalence, as though the environmental protection acquired in infancy and childhood, maybe related to the sunny climate of these regions (see below), is long lasting at adult age for these migrants.…”

Multiple sclerosis and vitamin D: an update

“…The suggestion that the risk of developing MS is largely determined before the age of 15 y has been questioned by Australian epidemiological data. The prevalence in the migrant population from the UK and Ireland in the different regions in Australia showed a significant correlation with latitude and was considerably less than in their countries of origin (Hammond et al, 2000). The epidemiological evidence suggests that UVR may play a protective role in three autoimmune diseases: MS, insulindependent diabetes mellitus, and rheumatoid arthritis has been reviewed (Ponsonby et al, 2002).…”