Magalhaes S, et al. - Researchers examined the link between early life sun exposure and risk of multiple sclerosis (MS) by analyzing data from a case-control study that included patients with MS and population-based control participants from Canada, Italy, and Norway and used the critical period vs the accumulation model. Participants were asked to report on sun exposure behaviors for 5-year age intervals from birth; the first three age intervals (≤15 years) were the primary focus of the study. The investigators evaluated data from 2,251 patients with MS and 4,028 control participants. Upon comparing the lowest reported summer sun exposure with highest, they noted a nearly 50% increased risk of MS with the accumulation model, which was considered to be the best model. Overall, they found that more time indoors during childhood and early adolescence was related to MS risk, and sun protection behaviors among individuals who spend most time indoors may play an integral role in increasing risk.