Daniele Urso, MD, Kings College London, London, UK, describes a study evaluating the association between neurofilament light chain (NfL) levels and non-motor symptoms (NMS) in patients with Parkinson’s disease (PD). In the study, serum and cerebrospinal fluid (CSF) NfL levels were predictive of worse Movement Disorder Society-sponsored Unified Parkinson’s Disease Rating Scale Part I (MDS-UPDRS-I) scores and depression over time. Longitudinal changes in serum and CSF NfL levels were also associated with worse longitudinal anxiety in patients with PD. Together, the results indicate that serum NfL holds potential as a non-invasive biomarker of NMS progression in PD. This interview took place during the AD/PD™ 2021 conference.