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

الملخص EN

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: rS = 0.38), Denmark (peak correlation at lag of 2 years: rS = 0.53), and UK (at lag of 1 year: rS = 0.50).

We found a positive correlation between received UV and MS incidences in the Nordland at lag of 1 year (rS = 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.