Background: These investigators examined the role of ultraviolet radiation (UVR) in MSers in four different populations, Italians, Danish, White and African Americans. They tested whether variation in UVR as determined by seasons (short term variation) and solar cycles (long term variation) is related to MS birth month and to survival as measured by lifespan.
Menni et al. Short and long term variation in ultraviolet radiation and multiple sclerosis. Int J Environ Res Public Health. 2012;9:685-97.
Methods: Cases were selected from three Italian MS Case Registries (2,737); from the United States National Center for Health Statistics (56,020); and from the Danish Multiple Sclerosis registry (15,900). Chi-square tests were used to study the pattern of month of birth distribution in MSers comparing with general population data. T-tests were employed to study solar cycles association with lifespan.
Results: A surplus of births was observed in June for White Americans. A decrease of births in October and November, though not significant after multiple testing correction, was observed in the three populations. In White American with MS overall, males and females, we found that solar cycle is associated with lifespan.
Conclusion: They found that season and solar cycles have some role in MS susceptibility and life duration. However, this is an exploratory analysis and further work is needed to discern the association.
“This work confirms data in the literature that conditions inside the womb during pregnancy are important for MS risk. This probably relates to vD levels, which is why we recommend vD supplements in pregnancy.”