Numerous studies have explored the use of plasma biomarkers in neurodegenerative diseases.8–13 Plasma p-tau217 has demonstrated high accuracy in detecting AD pathophysiology within the context of routine clinical practice in a memory clinic.8 In addition, plasma biomarkers such as the ratio of amyloid beta (Aβ)42 to Aβ40, neurofilament light (NEFL/NfL), and glial fibrillary acidic protein (GFAP) hold significant potential for AD diagnosis and monitoring.9,10 Similarly, plasma proteomic analysis in PD has revealed multiple novel biomarkers, such as DOPA decarboxylase (DDC). Here, NEFL is linked to Parkinson disease.