NEFL and early-onset autosomal dominant Alzheimer disease: A few potential cerebrospinal fluid (CSF) biomarkers have been investigated in patients with PD, including total α-synuclein, oligomeric α-synuclein, lysosomal enzyme activities, and neurofilament light chain.67However, differently from similar techniques used in Alzheimer's disease, PD CSF biomarkers for PD are not currently measured in routine clinical practice, been restricted to research protocols, for example, to investigate and determine pre-symptomatic stages in predisposed subjects.67