Simuni T, Chahine LM, Poston K, Brumm M, Buracchio T, Campbell M, Chowdhury S, Coffey C, Concha-Marambio L, Dam T, DiBiaso P, Foroud T, Frasier M, Gochanour C, Jennings D, Kieburtz K, Kopil CM, Merchant K, Mollenhauer B, Montine T, Nudelman K, Pagano G, Seibyl J, Sherer T, Singleton A, Stephenson D, Stern M, Soto C, Tanner CM, Tolosa E, Weintraub D, Xiao Y, Siderowf A, Dunn B, and Marek K
Parkinson's disease and dementia with Lewy bodies are currently defined by their clinical features, with α-synuclein pathology as the gold standard to establish the definitive diagnosis. We propose that, given biomarker advances enabling accurate detection of pathological α-synuclein (ie, misfolded and aggregated) in CSF using the seed amplification assay, it is time to redefine Parkinson's disease and dementia with Lewy bodies as neuronal α-synuclein disease rather than as clinical syndromes. This major shift from a clinical to a biological definition of Parkinson's disease and dementia with Lewy bodies takes advantage of the availability of tools to assess the gold standard for diagnosis of neuronal α-synuclein (n-αsyn) in human beings during life. Neuronal α-synuclein disease is defined by the presence of pathological n-αsyn species detected in vivo (S; the first biological anchor) regardless of the presence of any specific clinical syndrome. On the basis of this definition, we propose that individuals with pathological n-αsyn aggregates are at risk for dopaminergic neuronal dysfunction (D; the second biological anchor). Our biological definition establishes a staging system, the neuronal α-synuclein disease integrated staging system (NSD-ISS), rooted in the biological anchors (S and D) and the degree of functional impairment caused by clinical signs or symptoms. Stages 0-1 occur without signs or symptoms and are defined by the presence of pathogenic variants in the SNCA gene (stage 0), S alone (stage 1A), or S and D (stage 1B). The presence of clinical manifestations marks the transition to stage 2 and beyond. Stage 2 is characterised by subtle signs or symptoms but without functional impairment. Stages 2B-6 require both S and D and stage-specific increases in functional impairment. A biological definition of neuronal α-synuclein disease and an NSD-ISS research framework are essential to enable interventional trials at early disease stages. The NSD-ISS will evolve to include the incorporation of data-driven definitions of stage-specific functional anchors and additional biomarkers as they emerge and are validated. Presently, the NSD-ISS is intended for research use only; its application in the clinical setting is premature and inappropriate., Competing Interests: Declaration of interests TSi declares consultancies for 4D Pharma, Acadia, AcureX, AskBio, Amneal, Blue Rock Therapeutics, Caraway, Critical Path for Parkinson's Consortium, Denali, The Michael J Fox Foundation, Neuroderm, Roche, Sanofi, Sinopia, Sunovion, Takeda, UCB, Vanqua Bio, and Voyager. LMC declares research support and consulting fees from The Michael J Fox Foundation. KP declares consultancies for Curasen; was on a scientific advisory board for Curasen and Amprion; honoraria from invited scientific presentations to universities and professional societies not exceeding $5000 per year from California Congress of Clinical Neurology, California Neurological Society, and Johns Hopkins University; and patents or patent applications numbers 17/314,979 and 63/377,293. KP also declares grants to her institution (Stanford University School of Medicine) from NIH/NINDS NS115114, NS062684, NS075097, NIH/NIA U19 AG065156, P30 AG066515, The Michael J Fox Foundation, Lewy Body Dementia Association, Alzheimer's Drug Discovery Foundation, Sue Berghoff LBD Research Fellowship, and the Knight Initiative for Brain Resilience. MB declares travel grants from The Michael J Fox Foundation. SC declares employment for and travel grants from The Michael J Fox Foundation. The Michael J Fox Foundation received funding support from named non-profit institutions (Cure Parkinson's, Lewy Body Dementia Association, Parkinson Canada, Parkinson's UK, and Shake It Up Australia Foundation) to convene an in-person roundtable of experts in April 2023 in which The Michael J Fox Foundation (employer) cost-shared; The Michael J Fox Foundation (employer) provided funding for an in-person meeting in January, 2023. CC declares grants from The Michael J Fox Foundation and NIH/NINDS. LC-M declares employment for, and employee stock options in, Amprion; grants from The Michael J Fox Foundation; and patents or patent applications (numbers US 20210277076A1, US 20210311077A1, US 20190353669A1, and US 20210223268A1). TD declares former employment of and might hold stock or stock options in Biogen. TF declares travel grants and grant payments to her institution (Indiana University) from The Michael J Fox Foundation. MF declares employment for The Michael J Fox Foundation and an unpaid advisory role at Vaxxinity. CG declares research funding to her institution from The Michael J Fox Foundation. DJ declares employment for and employee stock options from Denali Therapeutics. KK declares support to his institution (University of Rochester Medical Center) from The Michael J Fox Foundation. CK declares employment for and travel grants from The Michael J Fox Foundation. KMe declares consultancies for The Michael J Fox Foundation, AcuRx, Caraway, Cerebral Therapeutics, NRG Therapeutics (scientific advisory board), Nitrase Therapeutics (scientific advisory board), Nurabio, Retromer Therapeutics (director on the board, part-time chief scientific officer), Schrodinger, Sinopia Biosciences (scientific advisory board), and Vanqua Biosciences (scientific advisory board); stock ownership for Cognition Therapeutics, Eli Lilly (retiree stock holder), Envisagenics, Nitrase Therapeutics, Sinopia Biosciences, and Retromer Therapeutics; honoraria for the University of Utah; patents or patent applications for Retromer Therapeutics (planned patent); a research grant from The Michael J Fox Foundation; and travel grants from the University of Utah. BM declares consultancies from Roche, Biogen, and The Michael J Fox Foundation; grants from The Michael J Fox Foundation, ASAP, and DFG; honoraria for AbbVie; and travel grants for AbbVie. TM declares support to his institution (Stanford University School of Medicine) from The Michael J Fox Foundation. KN declares support from The Michael J Fox Foundation. GP declares employment for F Hoffmann-La Roche and stock ownership for F Hoffmann-La Roche, Atea, Novartis, and Eli Lilly. JS declares consultancies from Invicro, Biogen, and AbbVie; and stock ownership from RealmIDX, MNI Holdings, and LikeMinds, as well as grants from The Michael J Fox Foundation. TSh declares employment for The Michael J Fox Foundation. ASin declares employment for NIH who received grants from The Michael J Fox Foundation and ASAP. ASin declares Diagnostic for Stroke royalties (unrelated to current work); honoraria from Movement Disorders Society and Nature Publishing Group; travel grants from Chan Zuckerberg Initiative, The Michael J Fox Foundation, and Weill Cornell. Asin's spouse is an employee of GeneDx. DS has no declarations. MS declared consultancies for Mediflix, and Health and Wellness Partners; honoraria from Atria Foundation, International Parkinson and Movement Disorder Society, Neurocrine, Luye Pharma, and Acorda. MS serves on advisory board at Neuroderm, Alexza, Alexion, and Biogen. CS declares employment for Amprion; stock ownership for Amprion; honoraria (will receive royalties for the sale of seed amplification assay) from Amprion; and patents or patent applications, awarded and amplified in conjunction with Amprion for the seed amplification assay. CT declares consultancies for CNS Ratings, Australian Parkinson's Mission, Biogen, Evidera, Cadent (data safety monitoring board), Adamas (steering committee), Biogen (via the Parkinson Study Group steering committee), Kyowa Kirin (advisory board), Lundbeck (advisory board), Jazz–Cavion (steering committee), Acorda (advisory board), Bial (DMC), and Genentech. CT also declares grant support to UCSF from The Michael J Fox Foundation, National Institute of Health, Gateway, Department of Defense, Roche Genentech, Biogen, Parkinson Foundation, and Marcus Program in Precision Medicine. DW declares salary support from The Michael J Fox Foundation for serving on an executive steering committee for the Parkinson Progression Markers Initiative. YX declares employment for and travel grants from The Michael J Fox Foundation. ASid declares consultancies for SPARC Therapeutics, Capsida Therapeutics, and Parkinson Study Group; honoraria from Bial; grants from The Michael J Fox Foundation (member of Parkinson Progression Markers Initiative steering committee), and NIH; and participation on board at Wave Life Sciences, Inhibikase, Prevail and Huntington Study Group, and Massachusetts General Hospital. BD has received consulting fees and travel support for his role as an advisor for Arch Venture Partners, Cerveau Technologies, Epilepsy Foundation, F-PRIME Capital, Loulou Foundation, and The Michael J Fox Foundation. BD has a leadership or fiduciary role in the Virginia Neurological Society (past president) and Prothena (Director). BD holds stock options with Prothena. KM declares support to his institution (Institute for Neurodegenerative Disorders) from The Michael J Fox Foundation. KMa also declares consultancies for Invicro, The Michael J Fox Foundation, Roche, Calico, Coave, Neuron23, Orbimed, Biohaven, Anofi, Koneksa, Merck, Lilly, Inhibikase, Neuramedy, IRLabs, and Prothena. KMa participates on DSMB at Biohaven. TB, MC, PD, and ET and declare no competing interests., (Copyright © 2024 Elsevier Ltd. All rights reserved.)