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Sasaki S. Long-term follow-up study of SWEDD patients with mild parkinsonian signs. BMJ Neurol Open 2024; 6:e000600. [PMID: 38665250 PMCID: PMC11043762 DOI: 10.1136/bmjno-2023-000600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 03/01/2024] [Indexed: 04/28/2024] Open
Abstract
Background Whether scan without evidence of dopaminergic deficit (SWEDD) can be a reliable indication of a clinical entity of Parkinson's disease (PD) is controversial. Objective To evaluate the proportion of SWEDD patients with mild parkinsonian signs who are classifiable as idiopathic PD. Methods 32 SWEDD patients with unilateral or asymmetric finger tremor with a rest component and unilateral rigidity (Unified Parkinson's Disease Rating Scale (UPDRS)-III scores of 3-5) were enrolled. They underwent longitudinal examination by UPDRS-III, Mini-Mental State Examination (MMSE), smell test and 123I-FP-CIT SPECT (DaTSCAN) at baseline (first DaTSCAN) and at follow-up (second DaTSCAN) after 27-83 months. Age-matched controls (n=112) also underwent MMSE and smell test. Results At follow-up, 21 of 32 SWEDD patients (65.6%) showed significantly reduced specific binding ratios below the normal range, that is, positive DaTSCAN, sometimes with increased asymmetry index (n=11). Among these 21 patients, the mean (SD) UPDRS-III score at follow-up was significantly higher than that at baseline (5.5 (2.2) vs 4.0 (0.5)) (p=0.003). The mean (SD) MMSE scores in SWEDD patients (n=32) at baseline and follow-up were not significantly different compared with those in controls. Olfactory function both in SWEDD patients with positive and negative DaTSCAN was significantly impaired versus controls (p<0.001), although no significant difference was recognised between patients with positive (n=21) and negative (n=11) second DaTSCAN. Conclusion The majority of SWEDD patients with mild rest tremor and rigidity could be classified as having idiopathic PD in this longitudinal and long-term follow-up study.
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Theis H, Pavese N, Rektorová I, van Eimeren T. Imaging Biomarkers in Prodromal and Earliest Phases of Parkinson's Disease. JOURNAL OF PARKINSON'S DISEASE 2024:JPD230385. [PMID: 38339941 DOI: 10.3233/jpd-230385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2024]
Abstract
Assessing imaging biomarker in the prodromal and early phases of Parkinson's disease (PD) is of great importance to ensure an early and safe diagnosis. In the last decades, imaging modalities advanced and are now able to assess many different aspects of neurodegeneration in PD. MRI sequences can measure iron content or neuromelanin. Apart from SPECT imaging with Ioflupane, more specific PET tracers to assess degeneration of the dopaminergic system are available. Furthermore, metabolic PET patterns can be used to anticipate a phenoconversion from prodromal PD to manifest PD. In this regard, it is worth mentioning that PET imaging of inflammation will gain significance. Molecular imaging of neurotransmitters like serotonin, noradrenaline and acetylcholine shed more light on non-motor symptoms. Outside of the brain, molecular imaging of the heart and gut is used to measure PD-related degeneration of the autonomous nervous system. Moreover, optical coherence tomography can noninvasively detect degeneration of retinal fibers as a potential biomarker in PD. In this review, we describe these state-of-the-art imaging modalities in early and prodromal PD and point out in how far these techniques can and will be used in the future to pave the way towards a biomarker-based staging of PD.
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Affiliation(s)
- Hendrik Theis
- University of Cologne, Faculty of Medicine and University Hospital Cologne, Department of Nuclear Medicine, Multimodal Neuroimaging Group, Cologne, Germany
- University of Cologne, Faculty of Medicine and University Hospital Cologne, Department of Neurology, Cologne, Germany
| | - Nicola Pavese
- Aarhus University, Institute of Clinical Medicine, Department of Nuclear Medicine & PET, Aarhus N, Denmark
- Newcastle University, Translational and Clinical Research Institute, Newcastle upon Tyne, United Kingdom
| | - Irena Rektorová
- Masaryk University, Faculty of Medicine and St. Anne's University Hospital, International Clinical Research Center, ICRC, Brno, Czech Republic
- Masaryk University, Faculty of Medicine and St. Anne's University Hospital, First Department of Neurology, Brno, Czech Republic
- Masaryk University, Applied Neuroscience Research Group, Central European Institute of Technology - CEITEC, Brno, Czech Republic
| | - Thilo van Eimeren
- University of Cologne, Faculty of Medicine and University Hospital Cologne, Department of Nuclear Medicine, Multimodal Neuroimaging Group, Cologne, Germany
- University of Cologne, Faculty of Medicine and University Hospital Cologne, Department of Neurology, Cologne, Germany
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3
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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, Marek K. A biological definition of neuronal α-synuclein disease: towards an integrated staging system for research. Lancet Neurol 2024; 23:178-190. [PMID: 38267190 DOI: 10.1016/s1474-4422(23)00405-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 09/27/2023] [Accepted: 10/06/2023] [Indexed: 01/26/2024]
Abstract
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.
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Affiliation(s)
- Tanya Simuni
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
| | - Lana M Chahine
- Department of Neurology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Kathleen Poston
- Department of Neurology, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Michael Brumm
- Department of Biostatistics, College of Public Health, University of Iowa, Iowa City, IA, USA
| | - Teresa Buracchio
- Center for Drug Evaluation and Research, Food and Drug Administration, Silver Spring, MD, USA
| | - Michelle Campbell
- Center for Drug Evaluation and Research, Food and Drug Administration, Silver Spring, MD, USA
| | - Sohini Chowdhury
- The Michael J Fox Foundation for Parkinson's Research, New York, NY, USA
| | - Christopher Coffey
- Department of Biostatistics, College of Public Health, University of Iowa, Iowa City, IA, USA
| | | | | | - Peter DiBiaso
- Patient Advisory Council, New York, NY, USA; Clinical Solutions and Strategic Partnerships, WCG Clinical, Princeton, NJ, USA
| | - Tatiana Foroud
- Department of Medical and Molecular Genetics, Indiana University, Indianapolis, IN, USA
| | - Mark Frasier
- The Michael J Fox Foundation for Parkinson's Research, New York, NY, USA
| | - Caroline Gochanour
- Department of Biostatistics, College of Public Health, University of Iowa, Iowa City, IA, USA
| | | | - Karl Kieburtz
- Department of Neurology, University of Rochester Medical Center, Rochester, NY, USA
| | - Catherine M Kopil
- The Michael J Fox Foundation for Parkinson's Research, New York, NY, USA
| | - Kalpana Merchant
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Brit Mollenhauer
- Department of Neurology, University Medical Center Göttingen and Paracelsus-Elena-Klinik, Kassel, Germany
| | - Thomas Montine
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA
| | - Kelly Nudelman
- Department of Medical and Molecular Genetics, Indiana University, Indianapolis, IN, USA
| | | | - John Seibyl
- Institute for Neurodegenerative Disorders, New Haven, CT, USA
| | - Todd Sherer
- The Michael J Fox Foundation for Parkinson's Research, New York, NY, USA
| | - Andrew Singleton
- National Institute on Aging, National Institutes of Health, Bethesda, MD, USA
| | - Diane Stephenson
- Critical Path for Parkinson's, Critical Path Institute, Tucson, AZ, USA
| | - Matthew Stern
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Claudio Soto
- Amprion, San Diego, CA, USA; Mitchell Center for Alzheimer's Disease and Related Brain Disorders, Department of Neurology, University of Texas McGovern Medical School at Houston, Houston, TX, USA
| | - Caroline M Tanner
- Movement Disorders and Neuromodulation Center, Department of Neurology, Weill Institute for Neuroscience, University of California, San Francisco, CA, USA; Parkinson's Disease Research Education and Clinical Center, San Francisco Veterans Affairs Health Care System, San Francisco, CA, USA
| | - Eduardo Tolosa
- Parkinson's Disease and Movement Disorders Unit, Neurology Service, Hospital Clínic de Barcelona, Barcelona, Spain; Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas, Hospital Clínic, IDIBAPS, Universitat de Barcelona, Barcelona, Spain
| | - Daniel Weintraub
- University of Pennsylvania and the Parkinson's Disease and Mental Illness Research, Education and Clinical Centers, Philadelphia Veterans Affairs Medical Center Philadelphia, PA, USA
| | - Yuge Xiao
- The Michael J Fox Foundation for Parkinson's Research, New York, NY, USA
| | - Andrew Siderowf
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Billy Dunn
- The Michael J Fox Foundation for Parkinson's Research, New York, NY, USA
| | - Kenneth Marek
- Institute for Neurodegenerative Disorders, New Haven, CT, USA
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Langley J, Hwang KS, Huddleston DE, Hu XP. Nigral volume loss in prodromal, early, and moderate Parkinson's disease. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.08.19.23294281. [PMID: 37645770 PMCID: PMC10462207 DOI: 10.1101/2023.08.19.23294281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
The loss of melanized neurons in the substantia nigra pars compacta (SNc) is a hallmark pathology in Parkinson's disease (PD). Melanized neurons in SNc can be visualized in vivo using magnetization transfer (MT) effects. Nigral volume was extracted in data acquired with a MT-prepared gradient echo sequence in 33 controls, 83 non-manifest carriers (42 LRRK2 and 41 GBA nonmanifest carriers), 65 prodromal hyposmic participants, 105 de novo PD patients and 26 48-month PD patients from the Parkinson's Progressive Markers Initiative. No difference in nigral volume was seen between controls and LRRK2 and GBA non-manifest carriers (F=0.076; P=0.927). A significant main effect in group was observed between controls, prodromal hyposmic participants, and overt PD patients (F=5.192; P=0.002). Longer disease duration significantly correlated with lower nigral volume (r=-0.252; P=0.010). This study shows that nigral depigmentation can be robustly detected in prodromal hyposmic participants and overt PD patients.
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Affiliation(s)
- Jason Langley
- Center for Advanced Neuroimaging, University of California Riverside, Riverside, CA, USA
| | - Kristy S. Hwang
- Department of Neurosciences, University of California San Diego, San Diego, CA, USA
| | | | - Xiaoping P. Hu
- Center for Advanced Neuroimaging, University of California Riverside, Riverside, CA, USA
- Department of Bioengineering, University of California Riverside, Riverside, CA, USA
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5
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Vaswani PA, Morley JF, Jennings D, Siderowf A, Marek K. Predictive value of abbreviated olfactory tests in prodromal Parkinson disease. NPJ Parkinsons Dis 2023; 9:103. [PMID: 37386033 DOI: 10.1038/s41531-023-00530-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 05/22/2023] [Indexed: 07/01/2023] Open
Abstract
There is disagreement in the literature whether olfaction may show specific impairments in Parkinson Disease (PD) and if olfactory tests comprised of selected odors could be more specific for diagnosis. We sought to validate previously proposed subsets of the University of Pennsylvania Smell Identification Test (UPSIT) odors for predicting conversion to PD in an independent, prodromal cohort. Conversion to PD was assessed in 229 participants in the Parkinson At Risk Study who completed baseline olfactory testing with the UPSIT and up to 12 years of clinical and imaging evaluations. No commercially available or proposed subset performed better than the full 40-item UPSIT. The proposed "PD-specific" subsets also did not perform better than expected by chance. We did not find evidence for selective olfactory impairment in Parkinson disease. Shorter odor identification tests, including commercially available 10-12 item tests, may have utility for ease of use and cost, but not for superior predictive value.
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Affiliation(s)
- Pavan A Vaswani
- Parkinson's Disease Research, Education and Clinical Center, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA, USA.
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - James F Morley
- Parkinson's Disease Research, Education and Clinical Center, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA, USA
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Danna Jennings
- The Institute for Neurodegenerative Disorders, New Haven, CT, USA
| | - Andrew Siderowf
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Kenneth Marek
- The Institute for Neurodegenerative Disorders, New Haven, CT, USA
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6
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Chahine LM, Merchant K, Siderowf A, Sherer T, Tanner C, Marek K, Simuni T. Proposal for a Biologic Staging System of Parkinson's Disease. JOURNAL OF PARKINSON'S DISEASE 2023; 13:297-309. [PMID: 37066922 DOI: 10.3233/jpd-225111] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
The Parkinson's disease (PD) research field has seen the advent of several promising biomarkers and a deeper understanding of the clinical features of the disease from the earliest stages of pathology to manifest disease. Despite progress, a biologically based PD staging system does not exist. Such staging would be a useful framework within which to model the disease, develop and validate biomarkers, guide therapeutic development, and inform clinical trials design. We propose that the presence of aggregated neuronal α-synuclein, dopaminergic neuron dysfunction/degeneration, and clinical signs and symptoms identifies a group of individuals that have Lewy body pathology, which in early stages manifests with what is now referred to as prodromal non-motor features and later stages with the manifestations of PD and related Lewy body diseases as defined by clinical diagnostic criteria. Based on the state of the field, we herein propose a definition and staging of PD based on biology. We present the biologic basis for such a staging system and review key assumptions and evidence that support the proposed approach. We identify gaps in knowledge and delineate crucial research priorities that will inform the ultimate integrated biologic staging system for PD.
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Affiliation(s)
- Lana M Chahine
- Department of Neurology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Kalpana Merchant
- Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Andrew Siderowf
- Department of Neurology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Todd Sherer
- The Michael J Fox Foundation for Parkinson's Research, New York, NY, USA
| | - Caroline Tanner
- Department of Neurology, Weill Institute for Neurosciences, University of San Francisco, San Francisco, CA, USA
| | | | - Tanya Simuni
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
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7
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Chahine LM, Simuni T. Role of novel endpoints and evaluations of response in Parkinson disease. HANDBOOK OF CLINICAL NEUROLOGY 2023; 193:325-345. [PMID: 36803820 DOI: 10.1016/b978-0-323-85555-6.00010-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
With progress in our understanding of Parkinson disease (PD) and other neurodegenerative disorders, from clinical features to imaging, genetic, and molecular characterization comes the opportunity to refine and revise how we measure these diseases and what outcome measures are used as endpoints in clinical trials. While several rater-, patient-, and milestone-based outcomes for PD exist that may serve as clinical trial endpoints, there remains an unmet need for endpoints that are clinically meaningful, patient centric while also being more objective and quantitative, less susceptible to effects of symptomatic therapy (for disease-modification trials), and that can be measured over a short period and yet accurately represent longer-term outcomes. Several novel outcomes that may be used as endpoints in PD clinical trials are in development, including digital measures of signs and symptoms, as well a growing array of imaging and biospecimen biomarkers. This chapter provides an overview of the state of PD outcome measures as of 2022, including considerations for selection of clinical trial endpoints in PD, advantages and limitations of existing measures, and emerging potential novel endpoints.
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Affiliation(s)
- Lana M Chahine
- Department of Neurology, University of Pittsburgh, Pittsburgh, PA, United States
| | - Tanya Simuni
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States.
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8
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Marras C, Alcalay RN, Siderowf A, Postuma RB. Challenges in the study of individuals at risk for Parkinson disease. HANDBOOK OF CLINICAL NEUROLOGY 2023; 192:219-229. [PMID: 36796944 DOI: 10.1016/b978-0-323-85538-9.00014-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Identifying individuals at high risk for developing neurodegenerative disease opens the possibility of conducting clinical trials that intervene at an earlier stage of neurodegeneration than has been possible to date, and in doing so hopefully improves the odds of efficacy for interventions aimed at slowing or stopping the disease process. The long prodromal phase of Parkinson disease presents opportunities and challenges to establishing cohorts of at-risk individuals. Recruiting people with genetic variants conferring increased risk and people with REM sleep behavior disorder currently constitutes the most promising strategies, but multistage screening of the general population may also be feasible capitalizing on known risk factors and prodromal features. This chapter discusses the challenges involved in identifying, recruiting, and retaining these individuals, and provides insights into possible solutions using examples from studies to date.
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Affiliation(s)
- Connie Marras
- The Edmond J Safra Program in PD, Toronto Western Hospital, University of Toronto, Toronto, ON, Canada.
| | - Roy N Alcalay
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, United States; Division of Movement Disorders, Neurological Institute, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - Andrew Siderowf
- Department of Neurology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, United States
| | - Ronald B Postuma
- Department of Neurology, McGill University, Montreal, QC, Canada
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Seibyl JP. Imaging Biomarkers for Central Nervous System Drug Development and Future Clinical Utility: Lessons from Neurodegenerative Disorders. J Nucl Med 2023; 64:12-19. [PMID: 36302659 DOI: 10.2967/jnumed.122.264773] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Revised: 09/28/2022] [Accepted: 09/28/2022] [Indexed: 01/07/2023] Open
Abstract
Diseases of the central nervous system are common and often chronic conditions associated with significant morbidity. In particular, neurodegenerative disorders including Alzheimer and Parkinson disease constitute a major health and socioeconomic challenge, with an increasing incidence in many industrialized countries with aging populations. Recent work has established the primary role of abnormal protein accumulation and the spread of disease-specific deposits in brain as a factor in neurotoxicity and disruption of functional networks. A range of therapeutics from small molecules to antibodies targeting these proteinopathies are now in phase 2 and phase 3 clinical trials. These studies are methodologically challenging because of difficulty in accurately diagnosing early disease, the slow and variable rates of progression between individuals, and efficacy measures that may be cofounded by symptomatic improvements due to treatment but not reflecting disease course modification. Further, the ideal candidates for these treatments would be at-risk, or premanifest, persons in whom the pathologic process of the neurodegenerative disorder has begun but who are clinically normal and extremely difficult to identify. Scintigraphic imaging with PET and SPECT in trials offers the opportunity to interrogate pathophysiologic processes such as protein deposition with high specificity. This review summarizes the current implementation of these imaging biomarkers and the implications for future management of neurodegenerative disorders and central nervous system drug development in general.
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Affiliation(s)
- John P Seibyl
- Institute for Neurodegenerative Disorders, New Haven, Connecticut
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Vaswani PA, Morley JF, Jennings D, Siderowf A, Marek K, Marek K, Seibyl J, Siderowf A, Stern M, Russell D, Sethi K, Frank S, Simuni T, Hauser R, Ravina B, Richards I, Liang G, Adler C, Saunders-Pullman R, Evatt ML, Lai E, Subramanian I, Hogarth P, Chung K. Serial olfactory testing for the diagnosis of prodromal Parkinson's disease in the PARS study. Parkinsonism Relat Disord 2022; 104:15-20. [PMID: 36194902 DOI: 10.1016/j.parkreldis.2022.09.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 08/28/2022] [Accepted: 09/11/2022] [Indexed: 01/09/2023]
Abstract
BACKGROUND The Parkinson Associated Risk Syndrome (PARS) study was designed to evaluate whether screening with olfactory testing and dopamine transporter (DAT) imaging could identify participants at risk for developing Parkinson's disease (PD). OBJECTIVE Hyposmia on a single test has been associated with increased risk of PD, but, taken alone, lacks specificity. We evaluated whether repeating olfactory testing improves the diagnostic characteristics of this screening approach. METHODS Participants completed up to 10 years of clinical and imaging evaluations in the PARS cohort. Olfaction was assessed with the University of Pennsylvania Smell Identification Test at baseline and on average 1.4 years later. Multiple logistic regression and Cox proportional hazards regression were used to estimate the hazard of development of clinical PD or abnormal DAT imaging. RESULTS Of 186 participants who were initially hyposmic, 28% reverted to normosmia on repeat testing (reverters). No initially normosmic subjects and only 2% of reverters developed DAT imaging progression or clinical PD, compared to 29% of subjects with persistent hyposmia who developed abnormal DAT and 20% who developed clinical PD. The relative risk of clinical conversion to PD was 8.3 (95% CI:0.92-75.2, p = 0.06) and of abnormal DAT scan was 12.5 (2.4-156.2, p = 0.005) for persistent hyposmia, compared to reversion. CONCLUSIONS Persistent hyposmia on serial olfactory testing significantly increases the risk of developing clinical PD and abnormal DAT imaging, compared to hyposmia on a single test. Repeat olfactory testing may be an efficient and cost-effective strategy to improve identification of at-risk patients for early diagnosis and disease modification studies.
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Affiliation(s)
- Pavan A Vaswani
- Parkinson's Disease Research, Education and Clinical Center, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA, USA; Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - James F Morley
- Parkinson's Disease Research, Education and Clinical Center, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA, USA; Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Danna Jennings
- Institute for Neurodegenerative Disorders, New Haven, CT, USA
| | - Andrew Siderowf
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Kenneth Marek
- Institute for Neurodegenerative Disorders, New Haven, CT, USA
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11
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Longitudinal clinical and biomarker characteristics of non-manifesting LRRK2 G2019S carriers in the PPMI cohort. NPJ Parkinsons Dis 2022; 8:140. [PMID: 36273008 PMCID: PMC9588016 DOI: 10.1038/s41531-022-00404-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 09/29/2022] [Indexed: 11/28/2022] Open
Abstract
We examined 2-year longitudinal change in clinical features and biomarkers in LRRK2 non-manifesting carriers (NMCs) versus healthy controls (HCs) enrolled in the Parkinson's Progression Markers Initiative (PPMI). We analyzed 2-year longitudinal data from 176 LRRK2 G2019S NMCs and 185 HCs. All participants were assessed annually with comprehensive motor and non-motor scales, dopamine transporter (DAT) imaging, and biofluid biomarkers. The latter included cerebrospinal fluid (CSF) Abeta, total tau and phospho-tau; serum urate and neurofilament light chain (NfL); and urine bis(monoacylglycerol) phosphate (BMP). At baseline, LRRK2 G2019S NMCs had a mean (SD) age of 62 (7.7) years and were 56% female. 13% had DAT deficit (defined as <65% of age/sex-expected lowest putamen SBR) and 11% had hyposmia (defined as ≤15th percentile for age and sex). Only 5 of 176 LRRK2 NMCs developed PD during follow-up. Although NMCs scored significantly worse on numerous clinical scales at baseline than HCs, there was no longitudinal change in any clinical measures over 2 years or in DAT binding. There were no longitudinal differences in CSF and serum biomarkers between NMCs and HCs. Urinary BMP was significantly elevated in NMCs at all time points but did not change longitudinally. Neither baseline biofluid biomarkers nor the presence of DAT deficit correlated with 2-year change in clinical outcomes. We observed no significant 2-year longitudinal change in clinical or biomarker measures in LRRK2 G2019S NMCs in this large, well-characterized cohort even in the participants with baseline DAT deficit. These findings highlight the essential need for further enrichment biomarker discovery in addition to DAT deficit and longer follow-up to enable the selection of NMCs at the highest risk for conversion to enable future prevention clinical trials.
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12
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Prange S, Theis H, Banwinkler M, van Eimeren T. Molecular Imaging in Parkinsonian Disorders—What’s New and Hot? Brain Sci 2022; 12:brainsci12091146. [PMID: 36138882 PMCID: PMC9496752 DOI: 10.3390/brainsci12091146] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 08/23/2022] [Accepted: 08/24/2022] [Indexed: 12/02/2022] Open
Abstract
Highlights Abstract Neurodegenerative parkinsonian disorders are characterized by a great diversity of clinical symptoms and underlying neuropathology, yet differential diagnosis during lifetime remains probabilistic. Molecular imaging is a powerful method to detect pathological changes in vivo on a cellular and molecular level with high specificity. Thereby, molecular imaging enables to investigate functional changes and pathological hallmarks in neurodegenerative disorders, thus allowing to better differentiate between different forms of degenerative parkinsonism, improve the accuracy of the clinical diagnosis and disentangle the pathophysiology of disease-related symptoms. The past decade led to significant progress in the field of molecular imaging, including the development of multiple new and promising radioactive tracers for single photon emission computed tomography (SPECT) and positron emission tomography (PET) as well as novel analytical methods. Here, we review the most recent advances in molecular imaging for the diagnosis, prognosis, and mechanistic understanding of parkinsonian disorders. First, advances in imaging of neurotransmission abnormalities, metabolism, synaptic density, inflammation, and pathological protein aggregation are reviewed, highlighting our renewed understanding regarding the multiplicity of neurodegenerative processes involved in parkinsonian disorders. Consequently, we review the role of molecular imaging in the context of disease-modifying interventions to follow neurodegeneration, ensure stratification, and target engagement in clinical trials.
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Affiliation(s)
- Stéphane Prange
- Multimodal Neuroimaging Group, Department of Nuclear Medicine, Faculty of Medicine, University Hospital of Cologne, University of Cologne, 50937 Cologne, Germany
- Institut des Sciences Cognitives Marc Jeannerod, CNRS, UMR 5229, Université de Lyon, 69675 Bron, France
- Correspondence: (S.P.); (T.v.E.); Tel.: +49-221-47882843 (T.v.E.)
| | - Hendrik Theis
- Multimodal Neuroimaging Group, Department of Nuclear Medicine, Faculty of Medicine, University Hospital of Cologne, University of Cologne, 50937 Cologne, Germany
- Department of Neurology, Faculty of Medicine, University Hospital of Cologne, University of Cologne, 50937 Cologne, Germany
| | - Magdalena Banwinkler
- Multimodal Neuroimaging Group, Department of Nuclear Medicine, Faculty of Medicine, University Hospital of Cologne, University of Cologne, 50937 Cologne, Germany
| | - Thilo van Eimeren
- Multimodal Neuroimaging Group, Department of Nuclear Medicine, Faculty of Medicine, University Hospital of Cologne, University of Cologne, 50937 Cologne, Germany
- Department of Neurology, Faculty of Medicine, University Hospital of Cologne, University of Cologne, 50937 Cologne, Germany
- Correspondence: (S.P.); (T.v.E.); Tel.: +49-221-47882843 (T.v.E.)
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Mirelman A, Siderowf A, Chahine L. Outcome Assessment in Parkinson Disease Prevention Trials: Utility of Clinical and Digital Measures. Neurology 2022; 99:52-60. [PMID: 35970590 DOI: 10.1212/wnl.0000000000200236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 01/21/2022] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND AND OBJECTIVES The prodromal phase of Parkinson disease (PD) is accompanied by subtle clinical signs that are not sufficient for diagnosis but could potentially be measured in the context of clinical trials of therapies intended to delay or prevent more definitive clinical features. The objective of this study was to review the available literature on the presence and time course of subtle motor features in prodromal PD in the context of planning for possible clinical trials. METHODS We reviewed the available literature based on expert opinion. We considered a range of outcomes including measurement of clinical features, patient-reported outcomes, digital markers, and clinical diagnosis. RESULTS We considered these features and measures in the context of patient stratification, intermediate outcomes, and clinically relevant end points, including phenoconversion. DISCUSSION Substantial progress has been made in understanding how motor features evolve in the period immediately before a PD diagnosis. Digital measures hold substantial progress for measurement precision and may be additionally relevant because they can be used in naturalistic environments outside the clinic. Future studies should focus on advancing digital sensor technology and analysis and developing methods to implement available methods, particularly determination of a clinical diagnosis of PD, in a clinical trial context.
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Affiliation(s)
- Anat Mirelman
- From the Sackler School of Medicine and Sagol School of Neuroscience (A.M.), Tel Aviv University, Israel; Department of Neurology (A.S.), Perelman School of Medicine, University of Pennsylvania, Philadelphia; and Department of Neurology (L.C.), University of Pittsburgh, PA
| | - Andrew Siderowf
- From the Sackler School of Medicine and Sagol School of Neuroscience (A.M.), Tel Aviv University, Israel; Department of Neurology (A.S.), Perelman School of Medicine, University of Pennsylvania, Philadelphia; and Department of Neurology (L.C.), University of Pittsburgh, PA.
| | - Lana Chahine
- From the Sackler School of Medicine and Sagol School of Neuroscience (A.M.), Tel Aviv University, Israel; Department of Neurology (A.S.), Perelman School of Medicine, University of Pennsylvania, Philadelphia; and Department of Neurology (L.C.), University of Pittsburgh, PA
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14
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Postuma RB. Neuroprotective Trials in REM Sleep Behavior Disorder: The Way Forward Becomes Clearer. Neurology 2022; 99:19-25. [PMID: 35970587 DOI: 10.1212/wnl.0000000000200235] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 01/21/2022] [Indexed: 01/02/2023] Open
Abstract
As neuroprotective therapies continue to be advanced against neurodegenerative synucleinopathies, such as Parkinson disease (PD), dementia with Lewy bodies (DLBs), and multiple system atrophy, increasing attention is turning to the prodromal stages of disease. Treatments at the prodromal stage have the compelling advantages of being applied early enough to make a meaningful difference and can be tested without confounding by symptomatic therapies used for clinical PD/DLB. As it currently stands, patients with idiopathic/isolated REM sleep behavior disorder (iRBD) represent the only large existing cohort of untreated prodromal PD/DLB that would be ready to start a clinical trial now. Several thousand patients with RBD are currently being followed in research-based clinics, and more than 80% of them will develop a full neurodegenerative synucleinopathy. Research into RBD phenoconversion rates and predictors has advanced considerably, and we are now able to generate increasingly precise estimates of progression rates, can select stratification markers to enrich trials, and are able to understand the progression and sample size implications of different primary outcome measures. This review will outline the potential for neuroprotective trials in iRBD, including the pathophysiologic mechanisms with the most promise to target in iRBD, selection criteria for inclusion, and the optimal primary trial outcome measures to choose.
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Affiliation(s)
- Ronald B Postuma
- From the Department of Neurology, McGill University, Montreal, Quebec, Canada.
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15
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Berg D, Crotty GF, Keavney JL, Schwarzschild MA, Simuni T, Tanner C. Path to Parkinson Disease Prevention: Conclusion and Outlook. Neurology 2022; 99:76-83. [PMID: 35970586 DOI: 10.1212/wnl.0000000000200793] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 04/12/2022] [Indexed: 01/19/2023] Open
Abstract
Tremendous progress in our understanding of the pathophysiology and clinical manifestations of the prodromal phase of Parkinson disease (PD) offers a unique opportunity to start therapeutic interventions as early as possible to slow or even stop the progression to clinically manifest motor PD. A Parkinson's Prevention Conference, "Planning for Prevention of Parkinson's: A trial design symposium and workshop" was convened to discuss all issues that need to be addressed before the launch of the first PD prevention study. In this review, we summarize the major opportunities and challenges in designing prevention trials in PD, organized by the following critical trial design questions: Who (should be enrolled)? What (to test)? How (to measure prevention)? and the pivotal question, When during the prodromal disease (should we start these trials)? We outline the implications of these questions and their meaning for a responsible, sustainable, and fruitful further planning for prevention trials. Despite the great progress that has been made, it needs to be acknowledged that several queries remain to be carefully considered and addressed because prevention trials are being planned and become a reality.
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Affiliation(s)
- Daniela Berg
- From the Department of Neurology (D.B.), Christian-Albrechts-University, Kiel, Germany; Molecular Neurobiology Laboratory (G.F.C., M.A.S.), Mass General Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital, Charlestown; Harvard Medical School (G.F.C., M.A.S.), Boston, MA; Parkinson's Foundation Research Advocates Program (J.L.K.), Parkinson's Foundation, Miami, FL/New York, NY; Northwestern University Feinberg School of Medicine (T.S.), Weill Institute for Neuroscience (C.T.), Department of Neurology, University of California - San Francisco; and Parkinson's Disease Research Education and Clinical Center (C.T.), San Francisco Veterans Affairs Medical Center
| | - Grace F Crotty
- From the Department of Neurology (D.B.), Christian-Albrechts-University, Kiel, Germany; Molecular Neurobiology Laboratory (G.F.C., M.A.S.), Mass General Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital, Charlestown; Harvard Medical School (G.F.C., M.A.S.), Boston, MA; Parkinson's Foundation Research Advocates Program (J.L.K.), Parkinson's Foundation, Miami, FL/New York, NY; Northwestern University Feinberg School of Medicine (T.S.), Weill Institute for Neuroscience (C.T.), Department of Neurology, University of California - San Francisco; and Parkinson's Disease Research Education and Clinical Center (C.T.), San Francisco Veterans Affairs Medical Center
| | - Jessi L Keavney
- From the Department of Neurology (D.B.), Christian-Albrechts-University, Kiel, Germany; Molecular Neurobiology Laboratory (G.F.C., M.A.S.), Mass General Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital, Charlestown; Harvard Medical School (G.F.C., M.A.S.), Boston, MA; Parkinson's Foundation Research Advocates Program (J.L.K.), Parkinson's Foundation, Miami, FL/New York, NY; Northwestern University Feinberg School of Medicine (T.S.), Weill Institute for Neuroscience (C.T.), Department of Neurology, University of California - San Francisco; and Parkinson's Disease Research Education and Clinical Center (C.T.), San Francisco Veterans Affairs Medical Center
| | - Michael A Schwarzschild
- From the Department of Neurology (D.B.), Christian-Albrechts-University, Kiel, Germany; Molecular Neurobiology Laboratory (G.F.C., M.A.S.), Mass General Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital, Charlestown; Harvard Medical School (G.F.C., M.A.S.), Boston, MA; Parkinson's Foundation Research Advocates Program (J.L.K.), Parkinson's Foundation, Miami, FL/New York, NY; Northwestern University Feinberg School of Medicine (T.S.), Weill Institute for Neuroscience (C.T.), Department of Neurology, University of California - San Francisco; and Parkinson's Disease Research Education and Clinical Center (C.T.), San Francisco Veterans Affairs Medical Center
| | - Tanya Simuni
- From the Department of Neurology (D.B.), Christian-Albrechts-University, Kiel, Germany; Molecular Neurobiology Laboratory (G.F.C., M.A.S.), Mass General Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital, Charlestown; Harvard Medical School (G.F.C., M.A.S.), Boston, MA; Parkinson's Foundation Research Advocates Program (J.L.K.), Parkinson's Foundation, Miami, FL/New York, NY; Northwestern University Feinberg School of Medicine (T.S.), Weill Institute for Neuroscience (C.T.), Department of Neurology, University of California - San Francisco; and Parkinson's Disease Research Education and Clinical Center (C.T.), San Francisco Veterans Affairs Medical Center.
| | - Caroline Tanner
- From the Department of Neurology (D.B.), Christian-Albrechts-University, Kiel, Germany; Molecular Neurobiology Laboratory (G.F.C., M.A.S.), Mass General Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital, Charlestown; Harvard Medical School (G.F.C., M.A.S.), Boston, MA; Parkinson's Foundation Research Advocates Program (J.L.K.), Parkinson's Foundation, Miami, FL/New York, NY; Northwestern University Feinberg School of Medicine (T.S.), Weill Institute for Neuroscience (C.T.), Department of Neurology, University of California - San Francisco; and Parkinson's Disease Research Education and Clinical Center (C.T.), San Francisco Veterans Affairs Medical Center
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Seibyl JP, Kuo P. What Is the Role of Dopamine Transporter Imaging in Parkinson Prevention Clinical Trials? Neurology 2022; 99:61-67. [PMID: 35970589 DOI: 10.1212/wnl.0000000000200786] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 04/11/2022] [Indexed: 12/17/2022] Open
Affiliation(s)
- John Peter Seibyl
- From the Institute for Neurodegenerative Disorders (J.P.S.), New Haven, CT; Department of Radiology (P.K.), University of Arizona, Tucson; and Invicro, LLC (P.K.), New Haven, CT.
| | - Phillip Kuo
- From the Institute for Neurodegenerative Disorders (J.P.S.), New Haven, CT; Department of Radiology (P.K.), University of Arizona, Tucson; and Invicro, LLC (P.K.), New Haven, CT
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Genetic factors affecting dopaminergic deterioration during the premotor stage of Parkinson disease. NPJ Parkinsons Dis 2021; 7:104. [PMID: 34836969 PMCID: PMC8626486 DOI: 10.1038/s41531-021-00250-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 11/04/2021] [Indexed: 12/14/2022] Open
Abstract
To estimate dopaminergic dysfunction in patients with Parkinson disease (PD) during the premotor stage and to investigate the effect of genetic factors on the trajectories. Using longitudinal dopamine transporter single-photon emission computed tomography data from 367 sporadic PD (sPD), 72 LRRK2 (G2019S), and 39 GBA (N370S) PD patients in the Parkinson's Progression Markers Initiative (PPMI) study, we estimated the temporal trajectories of putaminal-specific binding ratios using an integrating function between baseline values and their annual change rates. In order to test reproducibility, we computed another trajectory for sPD using positron emission tomography data of 38 sPD patients at Gangnam Severance Hospital (GSH). Temporal trajectories of sPD were compared between the groups separated by age at onset (AAO) and polygenic load for common PD risk variants, and also compared with genetic PD. sPD patients in both the PPMI and GSH cohorts showed similar onset of dopaminergic degeneration around 10 years before motor onset. Early-onset PD patients exhibited later onset of degeneration and a faster decline in dopaminergic activity during the premotor period than late-onset patients. sPD patients with high polygenic load were associated with earlier onset and slower progression of dopaminergic dysfunction. Compared to the sPD and LRRK2 PD groups, GBA PD patients exhibited faster deterioration of dopaminergic function during the premotor stage. Dopaminergic dysfunction in PD appears to start about 10 years before motor onset. Genetic factors may be contributing to the heterogeneity of dopaminergic deterioration during the premotor stage.
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Palermo G, Giannoni S, Bellini G, Siciliano G, Ceravolo R. Dopamine Transporter Imaging, Current Status of a Potential Biomarker: A Comprehensive Review. Int J Mol Sci 2021; 22:11234. [PMID: 34681899 PMCID: PMC8538800 DOI: 10.3390/ijms222011234] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Revised: 10/12/2021] [Accepted: 10/13/2021] [Indexed: 11/16/2022] Open
Abstract
A major goal of current clinical research in Parkinson's disease (PD) is the validation and standardization of biomarkers enabling early diagnosis, predicting outcomes, understanding PD pathophysiology, and demonstrating target engagement in clinical trials. Molecular imaging with specific dopamine-related tracers offers a practical indirect imaging biomarker of PD, serving as a powerful tool to assess the status of presynaptic nigrostriatal terminals. In this review we provide an update on the dopamine transporter (DAT) imaging in PD and translate recent findings to potentially valuable clinical practice applications. The role of DAT imaging as diagnostic, preclinical and predictive biomarker is discussed, especially in view of recent evidence questioning the incontrovertible correlation between striatal DAT binding and nigral cell or axon counts.
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Affiliation(s)
- Giovanni Palermo
- Unit of Neurology, Department of Clinical and Experimental Medicine, University of Pisa, 56126 Pisa, Italy; (G.P.); (S.G.); (G.B.); (G.S.)
| | - Sara Giannoni
- Unit of Neurology, Department of Clinical and Experimental Medicine, University of Pisa, 56126 Pisa, Italy; (G.P.); (S.G.); (G.B.); (G.S.)
- Unit of Neurology, San Giuseppe Hospital, 50053 Empoli, Italy
| | - Gabriele Bellini
- Unit of Neurology, Department of Clinical and Experimental Medicine, University of Pisa, 56126 Pisa, Italy; (G.P.); (S.G.); (G.B.); (G.S.)
| | - Gabriele Siciliano
- Unit of Neurology, Department of Clinical and Experimental Medicine, University of Pisa, 56126 Pisa, Italy; (G.P.); (S.G.); (G.B.); (G.S.)
| | - Roberto Ceravolo
- Unit of Neurology, Department of Clinical and Experimental Medicine, University of Pisa, 56126 Pisa, Italy; (G.P.); (S.G.); (G.B.); (G.S.)
- Center for Neurodegenerative Diseases, Unit of Neurology, Parkinson’s Disease and Movement Disorders, Department of Clinical and Experimental Medicine, University of Pisa, 56126 Pisa, Italy
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Dommershuijsen LJ, Boon AJW, Ikram MK. Probing the Pre-diagnostic Phase of Parkinson's Disease in Population-Based Studies. Front Neurol 2021; 12:702502. [PMID: 34276552 PMCID: PMC8284316 DOI: 10.3389/fneur.2021.702502] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 06/03/2021] [Indexed: 11/13/2022] Open
Abstract
Parkinson's disease covers a wide spectrum of symptoms, ranging from early non-motor symptoms to the characteristic bradykinesia, tremor and rigidity. Although differences in the symptomatology of Parkinson's disease are increasingly recognized, there is still a lack of insight into the heterogeneity of the pre-diagnostic phase of Parkinson's disease. In this perspective, we highlight three aspects regarding the role of population-based studies in providing new insights into the heterogeneity of pre-diagnostic Parkinson's disease. First we describe several specific advantages of population-based cohort studies, including the design which overcomes some common biases, the broad data collection and the high external validity. Second, we draw a parallel with the field of Alzheimer's disease to provide future directions to uncover the heterogeneity of pre-diagnostic Parkinson's disease. Finally, we anticipate on the emergence of prevention and disease-modification trials and the potential role of population-based studies herein. In the coming years, bridging gaps between study designs will be essential to make vital advances in elucidating the heterogeneity of pre-diagnostic Parkinson's disease.
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Affiliation(s)
| | - Agnita J. W. Boon
- Department of Neurology, Erasmus MC University Medical Center, Rotterdam, Netherlands
| | - M. Kamran Ikram
- Department of Epidemiology, Erasmus MC University Medical Center, Rotterdam, Netherlands
- Department of Neurology, Erasmus MC University Medical Center, Rotterdam, Netherlands
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