Browsing by Author "Simuni, Tanya"

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    A blood-based marker of mitochondrial DNA damage in Parkinson's disease
    (American Association for the Advancement of Science, 2023) Qi, Rui; Sammler, Esther; Gonzalez-Hunt, Claudia P.; Barraza, Ivana; Pena, Nicholas; Rouanet, Jeremy P.; Naaldijk, Yahaira; Goodson, Steven; Fuzzati, Marie; Blandini, Fabio; Erickson, Kirk I.; Weinstein, Andrea M.; Lutz, Michael W.; Kwok, John B.; Halliday, Glenda M.; Dzamko, Nicolas; Padmanabhan, Shalini; Alcalay, Roy N.; Waters, Cheryl; Hogarth, Penelope; Simuni, Tanya; Smith, Danielle; Marras, Connie; Tonelli, Francesca; Alessi, Dario R.; West, Andrew B.; Shiva, Sruti; Hilfiker, Sabine; Sanders, Laurie H.; Oral and Maxillofacial Surgery and Hospital Dentistry, School of Dentistry
    Parkinson's disease (PD) is the most common neurodegenerative movement disorder, and neuroprotective or disease-modifying interventions remain elusive. High-throughput markers aimed at stratifying patients on the basis of shared etiology are required to ensure the success of disease-modifying therapies in clinical trials. Mitochondrial dysfunction plays a prominent role in the pathogenesis of PD. Previously, we found brain region-specific accumulation of mitochondrial DNA (mtDNA) damage in PD neuronal culture and animal models, as well as in human PD postmortem brain tissue. To investigate mtDNA damage as a potential blood-based marker for PD, we describe herein a PCR-based assay (Mito DNADX) that allows for the accurate real-time quantification of mtDNA damage in a scalable platform. We found that mtDNA damage was increased in peripheral blood mononuclear cells derived from patients with idiopathic PD and those harboring the PD-associated leucine-rich repeat kinase 2 (LRRK2) G2019S mutation in comparison with age-matched controls. In addition, mtDNA damage was elevated in non-disease-manifesting LRRK2 mutation carriers, demonstrating that mtDNA damage can occur irrespective of a PD diagnosis. We further established that Lrrk2 G2019S knock-in mice displayed increased mtDNA damage, whereas Lrrk2 knockout mice showed fewer mtDNA lesions in the ventral midbrain, compared with wild-type control mice. Furthermore, a small-molecule kinase inhibitor of LRRK2 mitigated mtDNA damage in a rotenone PD rat midbrain neuron model and in idiopathic PD patient-derived lymphoblastoid cell lines. Quantifying mtDNA damage using the Mito DNADX assay may have utility as a candidate marker of PD and for measuring the pharmacodynamic response to LRRK2 kinase inhibitors.
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    Assessment of heterogeneity among participants in the Parkinson's Progression Markers Initiative cohort using α-synuclein seed amplification: a cross-sectional study
    (Elsevier, 2023) Siderowf, Andrew; Concha-Marambio, Luis; Lafontant, David-Erick; Farris, Carly M.; Ma, Yihua; Urenia, Paula A.; Nguyen, Hieu; Alcalay, Roy N.; Chahine, Lana M.; Foroud, Tatiana; Galasko, Douglas; Kieburtz, Karl; Merchant, Kalpana; Mollenhauer, Brit; Poston, Kathleen L.; Seibyl, John; Simuni, Tanya; Tanner, Caroline M.; Weintraub, Daniel; Videnovic, Aleksandar; Choi, Seung Ho; Kurth, Ryan; Caspell-Garcia, Chelsea; Coffey, Christopher S.; Frasier, Mark; Oliveira, Luis M. A.; Hutten, Samantha J.; Sherer, Todd; Marek, Kenneth; Soto, Claudio; Parkinson's Progression Markers Initiative; Medical and Molecular Genetics, School of Medicine
    Background: Emerging evidence shows that α-synuclein seed amplification assays (SAAs) have the potential to differentiate people with Parkinson's disease from healthy controls. We used the well characterised, multicentre Parkinson's Progression Markers Initiative (PPMI) cohort to further assess the diagnostic performance of the α-synuclein SAA and to examine whether the assay identifies heterogeneity among patients and enables the early identification of at-risk groups. Methods: This cross-sectional analysis is based on assessments done at enrolment for PPMI participants (including people with sporadic Parkinson's disease from LRRK2 and GBA variants, healthy controls, prodromal individuals with either rapid eye movement sleep behaviour disorder (RBD) or hyposmia, and non-manifesting carriers of LRRK2 and GBA variants) from 33 participating academic neurology outpatient practices worldwide (in Austria, Canada, France, Germany, Greece, Israel, Italy, the Netherlands, Norway, Spain, the UK, and the USA). α-synuclein SAA analysis of CSF was performed using previously described methods. We assessed the sensitivity and specificity of the α-synuclein SAA in participants with Parkinson's disease and healthy controls, including subgroups based on genetic and clinical features. We established the frequency of positive α-synuclein SAA results in prodromal participants (RBD and hyposmia) and non-manifesting carriers of genetic variants associated with Parkinson's disease, and compared α-synuclein SAA to clinical measures and other biomarkers. We used odds ratio estimates with 95% CIs to measure the association between α-synuclein SAA status and categorical measures, and two-sample 95% CIs from the resampling method to assess differences in medians between α-synuclein SAA positive and negative participants for continuous measures. A linear regression model was used to control for potential confounders such as age and sex. Findings: This analysis included 1123 participants who were enrolled between July 7, 2010, and July 4, 2019. Of these, 545 had Parkinson's disease, 163 were healthy controls, 54 were participants with scans without evidence of dopaminergic deficit, 51 were prodromal participants, and 310 were non-manifesting carriers. Sensitivity for Parkinson's disease was 87·7% (95% CI 84·9-90·5), and specificity for healthy controls was 96·3% (93·4-99·2). The sensitivity of the α-synuclein SAA in sporadic Parkinson's disease with the typical olfactory deficit was 98·6% (96·4-99·4). The proportion of positive α-synuclein SAA was lower than this figure in subgroups including LRRK2 Parkinson's disease (67·5% [59·2-75·8]) and participants with sporadic Parkinson's disease without olfactory deficit (78·3% [69·8-86·7]). Participants with LRRK2 variant and normal olfaction had an even lower α-synuclein SAA positivity rate (34·7% [21·4-48·0]). Among prodromal and at-risk groups, 44 (86%) of 51 of participants with RBD or hyposmia had positive α-synuclein SAA (16 of 18 with hyposmia, and 28 of 33 with RBD). 25 (8%) of 310 non-manifesting carriers (14 of 159 [9%] LRRK2 and 11 of 151 [7%] GBA) were positive. Interpretation: This study represents the largest analysis so far of the α-synuclein SAA for the biochemical diagnosis of Parkinson's disease. Our results show that the assay classifies people with Parkinson's disease with high sensitivity and specificity, provides information about molecular heterogeneity, and detects prodromal individuals before diagnosis. These findings suggest a crucial role for the α-synuclein SAA in therapeutic development, both to identify pathologically defined subgroups of people with Parkinson's disease and to establish biomarker-defined at-risk cohorts.
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    Common Variants Near ZIC1 and ZIC4 in Autopsy-Confirmed Multiple System Atrophy
    (Wiley, 2022-10) Hopfner, Franziska; Tietz, Anja K.; Ruf, Viktoria C.; Ross, Owen A.; Koga, Shunsuke; Dickson, Dennis; Aguzzi, Adriano; Attems, Johannes; Beach, Thomas; Beller, Allison; Cheshire, William P.; van Deerlin, Vivianna; Desplats, Paula; Deuschl, Günther; Duyckaerts, Charles; Ellinghaus, David; Evsyukov, Valentin; Flanagan, Margaret Ellen; Franke, Andre; Frosch, Matthew P.; Gearing, Marla; Gelpi, Ellen; van Gerpen, Jay A.; Ghetti, Bernardino; Glass, Jonathan D.; Grinberg, Lea T.; Halliday, Glenda; Helbig, Ingo; Höllerhage, Matthias; Huitinga, Inge; Irwin, David John; Keene, Dirk C.; Kovacs, Gabor G.; Lee, Edward B.; Levin, Johannes; Martí, Maria J.; Mackenzie, Ian; McKeith, Ian; Mclean, Catriona; Mollenhauer, Brit; Neumann, Manuela; Newell, Kathy L.; Pantelyat, Alex; Pendziwiat, Manuela; Peters, Annette; Porcel, Laura Molina; Rabano, Alberto; Matěj, Radoslav; Rajput, Alex; Rajput, Ali; Reimann, Regina; Scott, William K.; Seeley , William; Selvackadunco, Sashika; Simuni, Tanya; Stadelmann, Christine; Svenningsson, Per; Thomas, Alan; Trenkwalder, Claudia; Troakes, Claire; Trojanowski, John Q.; Uitti, Ryan J.; White, Charles L.; Wszolek, Zbigniew K.; Xie, Tao; Ximelis, Teresa; Justo, Yebenes; Alzheimer’s Disease Genetics Consortium; Müller, Ulrich; Schellenberg, Gerard D.; Herms, Jochen; Kuhlenbäumer, Gregor; Höglinger, Günter; Pathology and Laboratory Medicine, School of Medicine
    Background: Multiple System Atrophy is a rare neurodegenerative disease with alpha-synuclein aggregation in glial cytoplasmic inclusions and either predominant olivopontocerebellar atrophy or striatonigral degeneration, leading to dysautonomia, parkinsonism, and cerebellar ataxia. One prior genome-wide association study in mainly clinically diagnosed patients with Multiple System Atrophy failed to identify genetic variants predisposing for the disease. Objective: Since the clinical diagnosis of Multiple System Atrophy yields a high rate of misdiagnosis when compared to the neuropathological gold standard, we studied only autopsy-confirmed cases. Methods: We studied common genetic variations in Multiple System Atrophy cases (N = 731) and controls (N = 2898). Results: The most strongly disease-associated markers were rs16859966 on chromosome 3, rs7013955 on chromosome 8, and rs116607983 on chromosome 4 with P-values below 5 × 10−6, all of which were supported by at least one additional genotyped and several imputed single nucleotide polymorphisms. The genes closest to the chromosome 3 locus are ZIC1 and ZIC4 encoding the zinc finger proteins of cerebellum 1 and 4 (ZIC1 and ZIC4). Interpretation: Since mutations of ZIC1 and ZIC4 and paraneoplastic autoantibodies directed against ZIC4 are associated with severe cerebellar dysfunction, we conducted immunohistochemical analyses in brain tissue of the frontal cortex and the cerebellum from 24 Multiple System Atrophy patients. Strong immunohistochemical expression of ZIC4 was detected in a subset of neurons of the dentate nucleus in all healthy controls and in patients with striatonigral degeneration, whereas ZIC4-immunoreactive neurons were significantly reduced inpatients with olivopontocerebellar atrophy. These findings point to a potential ZIC4-mediated vulnerability of neurons in Multiple System Atrophy.
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    Dopamine transporter imaging predicts clinically-defined α-synucleinopathy in REM sleep behavior disorder
    (Wiley, 2021) Chahine, Lana M.; Brumm, Michael C.; Caspell-Garcia, Chelsea; Oertel, Wolfgang; Mollenhauer, Brit; Amara, Amy; Fernandez-Arcos, Ana; Tolosa, Eduardo; Simonet, Cristina; Hogl, Birgit; Videnovic, Aleksandar; Hutten, Samantha J.; Tanner, Caroline; Weintraub, Daniel; Burghardt, Elliot; Coffey, Christopher; Cho, Hyunkeun R.; Kieburtz, Karl; Poston, Kathleen L.; Merchant, Kalpana; Galasko, Douglas; Foroud, Tatiana; Siderowf, Andrew; Marek, Kenneth; Simuni, Tanya; Iranzo, Alex; Medical and Molecular Genetics, School of Medicine
    Introduction: Individuals with idiopathic rapid eye movement sleep behavior disorder (iRBD) are at high risk for a clinical diagnosis of an α-synucleinopathy (aSN). They could serve as a key population for disease-modifying trials. Abnormal dopamine transporter (DAT) imaging is a strong candidate biomarker for risk of aSN diagnosis in iRBD. Our primary objective was to identify a quantitative measure of DAT imaging that predicts diagnosis of clinically-defined aSN in iRBD. Methods: The sample included individuals with iRBD, early Parkinson's Disease (PD), and healthy controls (HC) enrolled in the Parkinson Progression Marker Initiative, a longitudinal, observational, international, multicenter study. The iRBD cohort was enriched with individuals with abnormal DAT binding at baseline. Motor and nonmotor measures were compared across groups. DAT specific binding ratios (SBR) were used to calculate the percent of expected DAT binding for age and sex using normative data from HCs. Receiver operative characteristic analyses identified a baseline DAT binding cutoff that distinguishes iRBD participants diagnosed with an aSN in follow-up versus those not diagnosed. Results: The sample included 38 with iRBD, 205 with PD, and 92 HC who underwent DAT-SPECT at baseline. Over 4.7 years of mean follow-up, 14 (36.84%) with iRBD were clinically diagnosed with aSN. Risk of aSN diagnosis was significantly elevated among those with baseline putamen SBR ≤ 48% of that expected for age and sex, relative to those above this cutoff (hazard ratio = 17.8 [95%CI: 3.79-83.3], P = 0.0003). Conclusion: We demonstrate the utility of DAT SBR to identify individuals with iRBD with increased short-term risk of an aSN diagnosis.
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    Genetic Testing in Parkinson's Disease
    (Wiley, 2023) Pal, Gian; Cook, Lola; Schulze, Jeanine; Verbrugge, Jennifer; Alcalay, Roy N.; Merello, Marcelo; Sue, Carolyn M.; Bardien, Soraya; Bonifati, Vincenzo; Chung, Sun Ju; Foroud, Tatiana; Gatto, Emilia; Hall, Anne; Hattori, Nobutaka; Lynch, Tim; Marder, Karen; Mascalzoni, Deborah; Novaković, Ivana; Thaler, Avner; Raymond, Deborah; Salari, Mehri; Shalash, Ali; Suchowersky, Oksana; Mencacci, Niccolò E.; Simuni, Tanya; Saunders-Pullman, Rachel; Klein, Christine; Medical and Molecular Genetics, School of Medicine
    Genetic testing for persons with Parkinson's disease is becoming increasingly common. Significant gains have been made regarding genetic testing methods, and testing is becoming more readily available in clinical, research, and direct-to-consumer settings. Although the potential utility of clinical testing is expanding, there are currently no proven gene-targeted therapies, but clinical trials are underway. Furthermore, genetic testing practices vary widely, as do knowledge and attitudes of relevant stakeholders. The specter of testing mandates financial, ethical, and physician engagement, and there is a need for guidelines to help navigate the myriad of challenges. However, to develop guidelines, gaps and controversies need to be clearly identified and analyzed. To this end, we first reviewed recent literature and subsequently identified gaps and controversies, some of which were partially addressed in the literature, but many of which are not well delineated or researched. Key gaps and controversies include: (1) Is genetic testing appropriate in symptomatic and asymptomatic individuals without medical actionability? (2) How, if at all, should testing vary based on ethnicity? (3) What are the long-term outcomes of consumer- and research-based genetic testing in presymptomatic PD? (4) What resources are needed for clinical genetic testing, and how is this impacted by models of care and cost-benefit considerations? Addressing these issues will help facilitate the development of consensus and guidelines regarding the approach and access to genetic testing and counseling. This is also needed to guide a multidisciplinary approach that accounts for cultural, geographic, and socioeconomic factors in developing testing guidelines.
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    Longitudinal Analysis of Multiple Neurotransmitter Metabolites in Cerebrospinal Fluid in Early Parkinson's Disease
    (Wiley, 2021-08) Kremer, Thomas; Taylor, Kirsten I.; Siebourg-Polster, Juliane; Gerken, Thomas; Staempfli, Andreas; Czech, Christian; Dukart, Juergen; Galasko, Douglas; Foroud, Tatiana; Chahine, Lana M.; Coffey, Christopher S.; Simuni, Tanya; Weintraub, Daniel; Seibyl, John; Poston, Kathleen L.; Toga, Arthur W.; Tanner, Caroline M.; Marek, Kenneth; Hutten, Samantha J.; Dziadek, Sebastian; Trenkwalder, Claudia; Pagano, Gennaro; Mollenhauer, Brit; Medical and Molecular Genetics, School of Medicine
    Background: Cerebrospinal fluid (CSF) levels of monoamine metabolites may represent biomarkers of Parkinson's disease (PD). Objective: The aim of this study was quantification of multiple metabolites in CSF from PD versus healthy control subjects (HCs), including longitudinal analysis. Methods: Absolute levels of multiple monoamine metabolites in CSF were quantified by liquid chromatography coupled with tandem mass spectrometry from 161 individuals with early PD and 115 HCs from the Parkinson's Progression Marker Initiative and de novo PD (DeNoPA) studies. Results: Baseline levels of homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC) were lower in individuals with PD compared with HCs. HVA levels correlated with Movement Disorder Society Unified Parkinson's Disease Rating Scale total scores (P < 0.01). Both HVA/dopamine and DOPAC/dopamine levels correlated with caudate nucleus and raw DOPAC with putamen dopamine transporter single-photon emission computed tomography uptake ratios (P < 0.01). No metabolite changed over 2 years in drug-naive individuals, but some changed on starting levodopa treatment. Conclusions: HVA and DOPAC CSF levels mirrored nigrostriatal pathway damage, confirming the central role of dopaminergic degeneration in early PD.
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    Longitudinal clinical and biomarker characteristics of non-manifesting LRRK2 G2019S carriers in the PPMI cohort
    (Springer, 2022-10-22) Simuni, Tanya; Merchant, Kalpana; Brumm, Michael C.; Cho, Hyunkeun; Caspell-Garcia, Chelsea; Coffey, Christopher S.; Chahine, Lana M.; Alcalay, Roy N.; Nudelman, Kelly; Foroud, Tatiana; Mollenhauer, Brit; Siderowf, Andrew; Tanner, Caroline; Iwaki, Hirotaka; Sherer, Todd; Marek, Kenneth; Parkinson’s Progression Marker Initiative Authors; Medical and Molecular Genetics, School of Medicine
    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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    Parkinson's disease variant detection and disclosure: PD GENEration, a North American study
    (Oxford University Press, 2024) Cook, Lola; Verbrugge, Jennifer; Schwantes-An, Tae-Hwi; Schulze, Jeanine; Foroud, Tatiana; Hall, Anne; Marder, Karen S.; Mata, Ignacio F.; Mencacci, Niccolò E.; Nance, Martha A.; Schwarzschild, Michael A.; Simuni, Tanya; Bressman, Susan; Wills, Anne-Marie; Fernandez, Hubert H.; Litvan, Irene; Lyons, Kelly E.; Shill, Holly A.; Singer, Carlos; Tropea, Thomas F.; Vanegas Arroyave, Nora; Carbonell, Janfreisy; Cruz Vicioso, Rossy; Katus, Linn; Quinn, Joseph F.; Hodges, Priscila D.; Meng, Yan; Strom, Samuel P.; Blauwendraat, Cornelis; Lohmann, Katja; Casaceli, Cynthia; Rao, Shilpa C.; Ghosh Galvelis, Kamalini; Naito, Anna; Beck, James C.; Alcalay, Roy N.; Medical and Molecular Genetics, School of Medicine
    Variants in seven genes (LRRK2, GBA1, PRKN, SNCA, PINK1, PARK7 and VPS35) have been formally adjudicated as causal contributors to Parkinson's disease; however, individuals with Parkinson's disease are often unaware of their genetic status since clinical testing is infrequently offered. As a result, genetic information is not incorporated into clinical care, and variant-targeted precision medicine trials struggle to enrol people with Parkinson's disease. Understanding the yield of genetic testing using an established gene panel in a large, geographically diverse North American population would help patients, clinicians, clinical researchers, laboratories and insurers better understand the importance of genetics in approaching Parkinson's disease. PD GENEration is an ongoing multi-centre, observational study (NCT04057794, NCT04994015) offering genetic testing with results disclosure and genetic counselling to those in the US (including Puerto Rico), Canada and the Dominican Republic, through local clinical sites or remotely through self-enrolment. DNA samples are analysed by next-generation sequencing including deletion/duplication analysis (Fulgent Genetics) with targeted testing of seven major Parkinson's disease-related genes. Variants classified as pathogenic/likely pathogenic/risk variants are disclosed to all tested participants by either neurologists or genetic counsellors. Demographic and clinical features are collected at baseline visits. Between September 2019 and June 2023, the study enrolled 10 510 participants across >85 centres, with 8301 having received results. Participants were: 59% male; 86% White, 2% Asian, 4% Black/African American, 9% Hispanic/Latino; mean age 67.4 ± 10.8 years. Reportable genetic variants were observed in 13% of all participants, including 18% of participants with one or more 'high risk factors' for a genetic aetiology: early onset (<50 years), high-risk ancestry (Ashkenazi Jewish/Basque/North African Berber), an affected first-degree relative; and, importantly, in 9.1% of people with none of these risk factors. Reportable variants in GBA1 were identified in 7.7% of all participants; 2.4% in LRRK2; 2.1% in PRKN; 0.1% in SNCA; and 0.2% in PINK1, PARK7 or VPS35 combined. Variants in more than one of the seven genes were identified in 0.4% of participants. Approximately 13% of study participants had a reportable genetic variant, with a 9% yield in people with no high-risk factors. This supports the promotion of universal access to genetic testing for Parkinson's disease, as well as therapeutic trials for GBA1 and LRRK2-related Parkinson's disease.
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    Parkinson's Progression Markers Initiative: A Milestone-Based Strategy to Monitor Parkinson's Disease Progression
    (IOS Press, 2023) Brumm, Michael C.; Siderowf, Andrew; Simuni, Tanya; Burghardt, Elliot; Choi, Seung Ho; Caspell-Garcia, Chelsea; Chahine, Lana M.; Mollenhauer, Brit; Foroud, Tatiana; Galasko, Douglas; Merchant, Kalpana; Arnedo, Vanessa; Hutten, Samantha J.; O’Grady, Alyssa N.; Poston, Kathleen L.; Tanner, Caroline M.; Weintraub, Daniel; Kieburtz, Karl; Marek, Kenneth; Coffey, Christopher S.; Parkinson’s Progression Markers Initiative; Medical and Molecular Genetics, School of Medicine
    Background: Identifying a meaningful progression metric for Parkinson's disease (PD) that reflects heterogeneity remains a challenge. Objective: To assess the frequency and baseline predictors of progression to clinically relevant motor and non-motor PD milestones. Methods: Using data from the Parkinson's Progression Markers Initiative (PPMI) de novo PD cohort, we monitored 25 milestones across six domains ("walking and balance"; "motor complications"; "cognition"; "autonomic dysfunction"; "functional dependence"; "activities of daily living"). Milestones were intended to be severe enough to reflect meaningful disability. We assessed the proportion of participants reaching any milestone; evaluated which occurred most frequently; and conducted a time-to-first-event analysis exploring whether baseline characteristics were associated with progression. Results: Half of participants reached at least one milestone within five years. Milestones within the cognitive, functional dependence, and autonomic dysfunction domains were reached most often. Among participants who reached a milestone at an annual follow-up visit and remained active in the study, 82% continued to meet criteria for any milestone at one or more subsequent annual visits and 55% did so at the next annual visit. In multivariable analysis, baseline features predicting faster time to reaching a milestone included age (p < 0.0001), greater MDS-UPDRS total scores (p < 0.0001), higher GDS-15 depression scores (p = 0.0341), lower dopamine transporter binding (p = 0.0043), and lower CSF total α-synuclein levels (p = 0.0030). Symptomatic treatment was not significantly associated with reaching a milestone (p = 0.1639). Conclusion: Clinically relevant milestones occur frequently, even in early PD. Milestones were significantly associated with baseline clinical and biological markers, but not with symptomatic treatment. Further studies are necessary to validate these results, further assess the stability of milestones, and explore translating them into an outcome measure suitable for observational and therapeutic studies.
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    Staged Screening Identifies People with Biomarkers Related to Neuronal Alpha-Synuclein Disease
    (Wiley, 2025) Brown, Ethan G.; Chahine, Lana M.; Siderowf, Andrew; Gochanour, Caroline; Kurth, Ryan; Marshall, Micah J.; Caspell-Garcia, Chelsea; Brumm, Michael C.; Stanley, Craig E., Jr.; Korell, Monica; McMahon, Bridget; Kuhl, Maggie; Fabrizio, Kimberly; Heathers, Laura; Concha-Marambio, Luis; Soto, Claudio; Chowdhury, Sohini; Coffey, Christopher S.; Foroud, Tatiana M.; Simuni, Tanya; Marek, Kenneth; Tanner, Caroline M.; Parkinson Progression Marker Initiative; Medical and Molecular Genetics, School of Medicine
    Objective: Remote identification of individuals with severe hyposmia may enable scalable recruitment of participants with underlying alpha-synuclein aggregation. We evaluated the performance of a staged screening paradigm using remote smell testing to enrich for abnormal dopamine transporter single-photon emission computed tomography imaging (DAT-SPECT) and alpha-synuclein aggregation. Methods: The Parkinson's Progression Markers Initiative (PPMI) recruited participants for the prodromal cohort who were 60-years and older without a Parkinson's disease diagnosis. Participants were invited to complete a University of Pennsylvania Smell Identification Test (UPSIT) independently through an online portal. Hyposmic participants were invited to complete DAT-SPECT, which determined eligibility for enrollment in longitudinal assessments and further biomarker evaluation including cerebrospinal fluid alpha-synuclein seed amplification assay (aSynSAA). Results: As of January 29, 2024, 49,843 participants were sent an UPSIT and 31,293 (63%) completed it. Of UPSIT completers, 8,301 (27%) scored <15th percentile. Of 1,546 who completed DAT-SPECT, 1,060 (69%) had DAT-SPECT binding <100% expected for age and sex. Participants with an UPSIT <10th percentile (n = 1,221) had greater likelihood of low DAT-SPECT binding compared to participants with an UPSIT in the 10th to 15th percentile (odds ratio, 3.01; 95% confidence interval, 1.85-4.91). Overall, 55% (198/363) of cases with UPSIT <15th percentile and DAT-SPECT <100% had positive aSynSAA, which increased to 70% (182/260) when selecting for more severe hyposmia (UPSIT <10th percentile). Interpretation: Remote screening for hyposmia and reduced DAT-SPECT binding identifies participants with a high proportion positive aSynSAA. Longitudinal data will be essential to define progression patterns in these individuals to ultimately inform recruitment into disease modification clinical trials.