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Article History

Received: 11 August 2025

Accepted: 3 February 2026

First Online: 24 March 2026

Competing interests

: O.S.M., B.T., E.C.T., B.H., R.L.A., J.W.A., U.K., K.F., Y.M., J. Czerkowicz, S.F. and D.L.G. are employees of Biogen and may hold Biogen stocks and/or shares. H.M.A. and J.I. are employees of Biogen. S.M.A., J. Chen, C.M.T. and E.B. declare no competing interests. T-Y.L. was employed by Biogen at the time of the study. A.A.S. was previously employed by Biogen and holds Biogen stock. K.E.G. was employed by Biogen at the time of the study, is currently an employee of Takeda and is a recipient of the ASAP grant. R.B.P. received grants from the Canadian Institute of Health Research, the Michael J. Fox Foundation, the National Institutes of Health, Roche Diagnostics and the Weston Foundation; received consulting fees from Novartis, Eisai, Merck, Vaxxinity, Bristol Myers Squibb, Ventus, Korro, Vanqua, Roche, Regeneron, Helicon, Epic, Clinilabs and AbbVie; and participates on boards for Parkinson Canada, the Michael J. Fox Foundation, the International Parkinson and Movement Disorders Society, the journal Movement Disorders and the RBD Study Group. T.G. received grant funding from the International Parkinson’s Disease and Movement Disorders Society and the Parkinson’s Foundation; consulting fees from AbbVie, Teva Pharmaceuticals, and Tradis Gat; honoraria from Medison; and support for attending meetings from AbbVie, Medison, AlphaMedix and Medtronic; was a co-founder of VocaVibe; participated on the advisory board for Cytora and Neurosteer; was the principal investigator of the present study (REASON trial); and received payment from Biogen for conducting the study. P.M. received financial support from the Spanish Ministry of Science and Innovation, the Instituto de Salud Carlos III–Fondo Europeo de Desarrollo Regional, the Consejería de Economía, Innovación, Ciencia y Empleo de la Junta de Andalucía, the Consejería de Salud y Bienestar Social de la Junta de Andalucía and the Consejería de Transformación Económica, Industria, Conocimiento y Universidades de la Junta de Andalucía and received support for attending meetings and/or honoraria from Abbott, Allergan, AbbVie, Bial, Britannia, Italfarmaco, Merz, UCB, Teva Pharmaceuticals and Zambon. H.R.M. received grants from PSP Association, Parkinson’s UK, the UK Medical Research Council, the Cure Parkinson’s Trust and the Michael J. Fox Foundation; received consulting fees from Aprinoia and AI Therapeutics; received honoraria from the Movement Disorders Society; and is a co-applicant on the patent “C9ORF72 – Method for diagnosing a neurodegenerative disease (PCT/GB2012/052140).” J.A. received funding from AbbVie, BioVie, Amneal Pharmaceuticals and IRLAB Therapeutics and received consulting fees and honoraria from AbbVie, Allergan, Boston Scientific, Teva Pharmaceuticals, US World Meds, Medtronic and Abbott. M.A.B. received consulting fees from Acadia Pharmaceuticals. A.E. received consulting fees and honoraria from AbbVie, Acorda, Ipsen, Revance, Supernus and Teva Pharmaceuticals; received consulting fees from BioVie, Cerevance, Cerevel and XW Labs; and received speaker honoraria from Arbor. D.L. received grants from the Michael J. Fox Foundation for Parkinson’s Research and the Parkinson’s Foundation and received speaker honoraria from Hyperkinetic Movement Disorders Tremor, Myoclonus and Chorea for the MDS-PAS Residents’ School of Neurology. A.S. received grants or contracts from the National Institute of Neurological Disorders and Stroke, the National Institute on Aging and the Michael J. Fox Foundation; received consulting fees from Aspen Neuroscience, Neurocrine, Theravance, Acadia, Boehringer Ingelheim, Capsida, General Electric and Mitsubishi; and participated on advisory boards for Massachusetts General Hospital, Clintrex, PTC Therapeutics, Inhibikase, Prevail, Prilenia, Wave Therapeutics, Cerevance and Spark. C.T. received honoraria from AbbVie, Desitin, Merz, Allergan and Biogen and was listed as inventor on patent applications relating to the use of nicotinamide riboside as a treatment for PD and related disorders. These patents have been filed by the technology transfer office Vestlandets Innovasjonsselskap AS (VIS) on behalf of Haukeland University Hospital (PCT/EP2022/067412, PCT/EP2023/060962, EP4284387). M.J.M. received grants from the Michael J. Fox Foundation for Parkinson’s Research and Instituto de Salud Carlos III, participated as a principal investigator for industry-sponsored clinical trials without receiving personal honoraria and has two patents planned, issued or pending, “Method for predicting L -DOPA induced dyskinesia onset and severity” and “Diagnostic method for multiple system atrophy.” H.T.Z., H.B.K. and R.L. are employees of Ionis Pharmaceuticals and may hold Ionis stocks and/or shares. W.D.H. was employed by Biogen, is currently employed by DaCapo Brainscience and holds stock in Biogen and DaCapo Brainscience.