NEFL and amyotrophic lateral sclerosis: As neuronal damage leads to the release of these proteins into the cerebrospinal fluid (CSF) and plasma, increased concentrations of NfL have been reported in neurological diseases such as amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS), and Alzheimer disease (AD) (Disanto et al., 2017; Mattsson et al., 2017; Rosengren et al., 1996).