Abstract
BackgroundWe noticed that a hypothesis based on the effect of geomagnetic disturbances (GMD) has the ability to explain special features of multiple sclerosis (MS). Areas around geomagnetic 60 degree latitude (GM60L) experience the greatest amount of GMD. The easiest way to evaluate our hypothesis was to test the association of MS prevalence (MSP) with angular distance to geomagnetic 60 degree latitude (AMAG60) and compare it with the known association of MS with geographical latitude (GL). We did the same with angular distance to geographic 60 degree latitude (AGRAPH60) as a control.MethodsEnglish written papers with MSP keywords, done in Europe (EUR), North America (NA) or Australasia (AUS) were retrieved from the PubMed. Geomagnetic coordinates were determined for each location and AMAG60 was calculated as absolute value of numerical difference between its geomagnetic latitude from GM60L. By an ecological study with using meta-regression analyses, the relationship of MSP with GL, AMAG60 and AGRAPH60 were evaluated separately. MSP data were weighted by square root of number of prevalent cases. Models were compared by their adjusted R square (AR2) and standard error of estimate (SEE).Results111 MSP data were entered in the study. In each continent, AMAG60 had the best correlation with MSP, the largest AR2 (0.47, 0.42 and 0.84 for EUR, NA and AUS, respectively) and the least SEE. Merging both hemispheres data, AMAG60 explained 56% of MSP variations with the least SEE (R = 0.75, AR2 = 0.56, SEE = 57), while GL explained 17% (R = 0.41, AR2 = 0.17, SEE = 78.5) and AGRAPH60 explained 12% of that variations with the highest SEE (R = 0.35, AR2 = 0.12, SEE = 80.5).ConclusionsOur results confirmed that AMAG60 is the best describer of MSP variations and has the strongest association with MSP distribution. They clarified that the well-known latitudinal gradient of MSP may be actually a gradient related to GM60L. Moreover, the location of GM60L can elucidate why MSP has parabolic and linear gradient in the north and south hemisphere, respectively. This preliminary evaluation supported that GMD can be the mysterious environmental risk factor for MS. We believe that this hypothesis deserves to be considered for further validation studies.
Highlights
We noticed that a hypothesis based on the effect of geomagnetic disturbances (GMD) has the ability to explain special features of multiple sclerosis (MS)
Search strategy and selection criteria As the most accurate MS prevalence studies have been done in western countries, we retrieved English written papers with the keywords of “prevalence” or “epidemiology” and “multiple sclerosis” in the title, published since 1980 up to the 2010, from the PubMed that were done in western countries
AGRAPH60 model showed the weakest association with MS prevalence in each continent, with the least adjusted R2 (AR2) and the greatest standard error of estimate (SEE)
Summary
We noticed that a hypothesis based on the effect of geomagnetic disturbances (GMD) has the ability to explain special features of multiple sclerosis (MS). It is repeatedly tested and accepted that MS prevalence has a latitudinal gradient and its prevalence has a positive relation to the distance from the equator [3] Based on this fact, all efforts have been toward finding a hypothesis that explains MS etiology by an environmental factor that change in agreement with this feature. All efforts have been toward finding a hypothesis that explains MS etiology by an environmental factor that change in agreement with this feature According to this opinion, the recent hypothesis that tries to explain MS prevalence distribution and etiology by the possible immunomodulatory effect of vitamin D [4] seems to be reasonable, because of the common belief that production of vitamin D is related to the amount of received solar ultra-violet radiation and expected to have a latitudinal gradient
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