By contrast, the Dominantly Inherited Alzheimer Network modelled that serum NfL was elevated in the presymptomatic stages of familial Alzheimer’s disease; specifically, longitudinal, within-person analysis showed that the rate of change of NfL discriminated mutation carriers from non-mutation carriers almost 10 years earlier than cross-sectional, absolute NfL levels.37 This evidence concerns the gene NEFL and familial Alzheimer disease.