NEFL and neurodegenerative disease: Neurofilament light chain (NfL) is a blood marker sensitive to neuroaxonal damage and increased levels occur in neurodegenerative diseases.4 5 In a cross-sectional study in SVD, NfL levels were associated with cognition and disability.6 However, if NfL is to be used to predict outcome, studies are required to demonstrate baseline NfL predicts future dementia risk.