Truly benign multiple sclerosis is rare: let’s stop fooling ourselves - Commentary

Background: Vitamin D insufficiency is one of the factors that consistently have been shown to be associated with an increased of developing multiple sclerosis (MS). This study aims estimate the association between sun exposure as an indirectmeasure of vitamin D status at various age periods during childhood adolescence and the risk of MS and to look for possible between Norway and Italy. : The data for this study are from EnvIMS, a large multinational -control study, and includes 733 cases and 1438 based controls from Italy and 959 cases and 1718 based controls from Norway. The exposure information collected by means of a standardized self-administered that included questions about sun habits during periods in childhood and adolescence. The participants asked to recall the amount of time spent outdoors and use sunscreen during the same time periods. Effect estimates were using logistic regression contrasting “no outdoor activity” “being outside most of the time ” adjusting for relevant confounding factors. : Adjusting for sex we found a significant inverse association time spent outdoors and MS both in Norway and Italy. In Norway the association was strongest with little sun in the summer between age 16 and 18 years (OR=1.79, 95% Cl[1.28 - 2.52]), while the period from age 0 to 5 years the strongest effect in Italy (OR= 1.57, 95% Cl [1.17 - 2.12]). We also found a statistically significant inverse association the winter in Italy (OR= 1.45, 95% Cl [1.05 - 2.00]), not in Norway. High sunscreen use between the age of 0 and 6 years was associated with an increased risk of MS in Norway (OR=1.59, 95% Cl [1.23 - 2.04]) after adjusting for sun exposure the same period. : Sun exposure was found to be inversely associated MS both in Norway and in Italy, with the strongest effect early childhood in Italy and in late adolescence in Norway. effect of seasonal variations was greater in Norway with association with sun exposure in the winter. Further, high of sunscreen in early childhood was linked to MS in Norway. sun exposure as a proxy of vitamin D exposure, study gives further support for the importance of vitamin in relation to MS. The findings suggest a possible age variation to country/latitude in risk of MS due to vitamin insufficiency.