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Multiple Sclerosis International
Volume 2017 (2017), Article ID 4960386, 11 pages
https://doi.org/10.1155/2017/4960386
Research Article

Which Environmental Factor Is Correlated with Long-Term Multiple Sclerosis Incidence Trends: Ultraviolet B Radiation or Geomagnetic Disturbances?

1Neuroscience Research Center, Faculty of Medicine, Golestan University of Medical Sciences, Gorgan, Iran
2Department of Neurology, Sayyad Shirazi Hospital, Golestan University of Medical Sciences, Gorgan, Iran
3Multiple Sclerosis Center, Golestan Hospital, Ahvaz, Iran
4Department of Internal Medicine, Sayyad Shirazi Hospital, Golestan University of Medical Sciences, Gorgan, Iran

Correspondence should be addressed to Seyed Aidin Sajedi; moc.liamg@ydejas.rd

Received 11 April 2017; Revised 20 August 2017; Accepted 30 August 2017; Published 24 October 2017

Academic Editor: Bianca Weinstock-Guttman

Copyright © 2017 Seyed Aidin Sajedi and Fahimeh Abdollahi. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background. Insufficient received ultraviolet B radiation (UV) is regarded as the main environmental risk factor (RF) for MS in vitamin D deficiency hypothesis. Nevertheless, geomagnetic disturbance (GMD) has also been proposed as a potential trigger for MS in GMD hypothesis. The aim of this study was to investigate which of these mentioned RF is correlated with long-term ultradecadal MS incidence. Methods. After a systematic search, long-term incidence reports of the United Kingdom (UK), Denmark, Tayside County, Nordland County, the Orkney, and Shetland Islands were selected for this retrospective time-series study. Possible lead-lag relationships between MS incidence, GMD, and UV were evaluated by cross-correlation analysis. Results. Significant positive correlations between GMD and MS incidence were seen in Tayside County (at lag of 2 years: = 0.38), Denmark (peak correlation at lag of 2 years: = 0.53), and UK (at lag of 1 year: = 0.50). We found a positive correlation between received UV and MS incidences in the Nordland at lag of 1 year ( = 0.49). Conclusion. This study found significant positive correlations between alterations in GMD with alterations in long-term MS incidence in three out of six studied locations and supports the GMD hypothesis. The observed significant correlation between MS and UV is positive; hence it is not supportive for UV related vitamin D deficiency hypothesis.