NEFL and multiple sclerosis: Measurement of plasma NfL has also been used in trials of several other neurodegenerative diseases, including Parkinson’s disease, multiple sclerosis, and Alzheimer’s disease, further speaking to the validity of this protein as a nonspecific biomarker of neurodegeneration (Gagliardi et al., 2019; Sormani et al., 2019; Committee PaCNSDA, 2022).