Importance Unrecognized demyelinating events often precede the clinical onset of multiple
sclerosis (MS). Identification of these events at the time of occurrence would have
implications for early diagnosis and the search of causal factors for the disease. Objective To
assess whether serum neurofilament light chain (sNfL) levels are elevated before the clinical
MS onset. Design, Setting, and Participants Nested case-control study among US military
personnel who have serum samples stored in the US Department of Defense Serum …