Multipe Sclerosis - Treatment

Sunlight - updated: 16 November 2009

Explaining multiple sclerosis prevalence by ultraviolet exposure: a geospatial analysis

Mult Scler. 2009 Aug;15(8):891-8

Beretich BD, Beretich TM.

BACKGROUND: Epidemiologic studies have shown a positive correlation of multiple sclerosis (MS) prevalence with latitude. However, there has not been a causal association found. Increased dietary intake and increased serum levels of vitamin D showed to be protective for the development of MS. Ultraviolet (UV) radiation plays an important role in vitamin D synthesis and could potentially explain both latitude differences in MS prevalence and the low levels of vitamin D in individuals with MS. OBJECTIVE: To evaluate the relationship between UV radiation and MS prevalence using geospatial analysis. METHODS: Geospatial analysis was performed on North American regions and separately for the continental United States. The correlation of UV radiation (measured as UV index [UVI]) versus MS prevalence and UV radiation versus case-control ratios was calculated. In addition, the relative risk (RR) of MS was determined for regions/states with low UV radiation exposure. RESULTS: Case-control ratios by US state and MS prevalence by North American region showed a strong negative (inverse) correlation with UVI (R = -0.72 and -0.86, respectively). The RR for the five highest risk states/lowest UVI versus the five lowest risk states/highest UVI was increased (RR = 1.8-5.4). The RR for MS, when comparing North American regions with lowest and highest UVI, was 3.78 and within US regions was 1.52. CONCLUSION: This analysis suggests a strong association between UV radiation and MS distribution, and an increase in risk for MS in those areas with a low UVI.

Publication Types:

• geospatial analysis

Past environmental sun exposure and risk of multiple sclerosis: a role for the Cdx-2 Vitamin D receptor variant in this interaction

Mult Scler. 2009 May;15(5):563-70.

Dickinson JL, Perera DI, van der Mei AF, Ponsonby AL, Polanowski AM, Thomson RJ, Taylor BV, McKay JD, Stankovich J, Dwyer T.

Multiple studies have provided evidence for an association between reduced sun exposure and increased risk of multiple sclerosis (MS), an association likely to be mediated, at least in part, by the vitamin D hormonal pathway. Herein, we examine whether the vitamin D receptor (VDR), an integral component of this pathway, influences MS risk in a population-based sample where winter sun exposure in early childhood has been found to be an important determinant of MS risk. Three polymorphisms within the VDR gene were genotyped in 136 MS cases and 235 controls, and associations with MS and past sun exposure were examined by logistic regression. No significant univariate associations between the polymorphisms, rs11574010 (Cdx-2A > G), rs10735810 (Fok1T > C), or rs731236 (Taq1C > T) and MS risk were observed. However, a significant interaction was observed between winter sun exposure during childhood, genotype at rs11574010, and MS risk (P = 0.012), with the 'G' allele conferring an increased risk of MS in the low sun exposure group (

Publication Types:

• Case Control

Monthly ambient sunlight, infections and relapse rates in multiple sclerosis

Neuroepidemiology. 2008;31(4):271-9. Epub 2008 Oct 30

Tremlett H, van der Mei IA, Pittas F, Blizzard L, Paley G, Mesaros D, Woodbaker R, Nunez M, Dwyer T, Taylor BV, Ponsonby AL.

BACKGROUND: Monthly variation in multiple sclerosis (MS) relapses has been found. The relationship between seasonal environmental factors, infections, serum vitamin D [25(OH)D] and MS relapses is undetermined. METHODS: We prospectively followed a population-based cohort of relapsing-remitting (RR) MS patients in Southern Tasmania for a mean 2.3 years (January 2002-April 2005). Associations between monthly ambient environmental factors, estimated serum 25(OH)D, upper respiratory tract (URT) infections and relapse rates were examined using weighted Pearson's correlation and linear regression. RESULTS: Of 199 definite MS patients, 142 had RRMS. The lowest relapse rate of 0.5 per 1,000 days (95% CI: 0.2-1.3) occurred in February (mid-late summer) versus the March-January RR of 1.1 per 1,000 days (95% CI: 0.9-1.3; p = 0.018, weighted regression). Monthly relapse rates correlated with: (1) prior erythemal ultraviolet radiation (EUV): lagged 1.5 months, r = -0.32, p = 0.046; (2) URT infection rate: no lag, r = 0.39, p = 0.014; (3) 25(OH)D: no lag, r = -0.31, p = 0.057. The association between URT infections and relapses was reduced after adjustment for monthly EUV. CONCLUSIONS: Relapse rates were inversely associated with EUV and serum 25(OH)D levels and positively associated with URT infections. The demonstrated lag between EUV but not 25(OH)D and relapse rates is consistent with a role for EUV-generated 25(OH)D in the alteration of relapse rates. Future work on the association between URT infections and relapses should be considered in the context of ultraviolet radiation and vitamin D.

Publication Types:

• Study

Publication Types:

• Review