Citations

ABSTRACT Background With pathway‐specific trials in PD associated with variants in the glucocerebrosidase gene (PD GBA ) under way, we need markers that confirm the impact of genetic variants in patient‐derived biofluids in order to allow patient stratification merely based on genetics and that might serve as biochemical read‐out for target engagement. Objective To explore GBA‐pathway‐specific biomarker profiles cross‐sectionally (TUEPAC‐MIGAP, PPMI) and longitudinally (PPMI). Methods We measured enzyme activity of the lysosomal glucocerebrosidase, CSF levels of glucosylceramides (upstream substrate of glucocerebrosidase), CSF levels of ceramides (downstream product of glucocerebrosidase), lactosylceramides, sphingosines, sphingomyelin (by‐products) and CSF levels of total α‐synuclein in PD GBA patients compared to PD GBA_wildtype patients. Results Cross‐sectionally in both cohorts and longitudinally in PPMI: (1) glucocerebrosidase activity was significantly lower in PD GBA compared to PD GBA_wildtype . (2) CSF levels of upstream substrates (glucosylceramides species) were higher in PD GBA compared to PD GBA_wildtype . (3) CSF levels of total α‐synuclein were lower in PD GBA compared to PD GBA_wildtype . All of these findings were most pronounced in PD GBA with severe mutations (PD GBA_severe ). Cross‐sectionally in TUEPAC‐MIGAP and longitudinally in PPMI, CSF levels of downstream‐products (ceramides) were higher in PD GBA_severe . Cross‐sectionally in TUEPAC‐MIGAP by‐products sphinganine and sphingosine‐1‐phosphate and longitudinally in PPMI species of by‐products lactosylceramides and sphingomyelin were higher in PD GBA_severe . Interpretation These findings confirm that GBA mutations have a relevant functional impact on biomarker profiles in patients. Bridging the gap between genetics and biochemical profiles now allows patient stratification for clinical trials merely based on mutation status. Importantly, all findings were most prominent in PD GBA with severe variants. © 2021 International Parkinson and Movement Disorder Society

AbstractBackgroundPost‐mortem assessment remains the only option and a gold standard for a definitive diagnosis of Parkinson’s disease (PD). The antemortem diagnosis is challenging due to a variable clinical presentation and the abundance of mimicking conditions, obscuring the clinical picture and delaying the treatment. It is well established that while PD pathologically manifests in central nervous system with aggregation of α‐synuclein as Lewy bodies and Lewy neurites, this pathology is also found in the peripheral nervous system. Peripheral Lewy‐type synucleinopathy (LTS) is present in early PD, suggesting its utility as a diagnostic and prognostic biomarker. We have previously confirmed that detection of LTS in submandibular gland (SMG) biopsies is sensitive (.75) and specific (.90) for early PD. However, the assessment by a neuropathologist of multiple levels of such biopsy is laborious and time‐consuming.MethodHere work we applied two Convolutional Neural Networks (CNN) for detection of LTS on 283 digital whole slide images (WSI) from 95 unique SMG biopsies. A total number of 8,386 LTS were annotated following the interrater reliability study with kappa=.7. We used transfer learning to train a CNN model to classify image patches (40‐by‐40 pixels at 20x) with and without presence of LTS objects.ResultThe trained CNNs showed the following performance on image patches: sensitivity: .982/.988, specificity: .998/.999, precision: .852/.950, accuracy: .995/.998, and F‐1 score .912/.968 for ResNet30/InceptionV4 respectively. On test WSI the sensitivity in detecting LTS was .963/.971 respectively.ConclusionThis work is first to demonstrate the practical utility of an CNN for screening for LTS, which can further translate into a practical screening tool facilitating the antemortem diagnosis of PD. We further plan to develop neural networks for accurate and precise detection and quantification of LTS in antemortem SMG biopsies. This, altogether, would offer a screening, confirmatory, prognostic, and quantitative tool for clinical assessment of early PD.

ABSTRACT Background There is only partial overlap in the genetic background of isolated rapid‐eye‐movement sleep behavior disorder (iRBD) and Parkinson's disease (PD). Objective To examine the role of autosomal dominant and recessive PD or atypical parkinsonism genes in the risk of iRBD. Methods Ten genes, comprising the recessive genes PRKN , DJ‐1 (PARK7) , PINK1 , VPS13C , ATP13A2 , FBXO7 , and PLA2G6 and the dominant genes LRRK2 , GCH1 , and VPS35 , were fully sequenced in 1039 iRBD patients and 1852 controls of European ancestry, followed by association tests. Results We found no association between rare heterozygous variants in the tested genes and risk of iRBD. Several homozygous and compound heterozygous carriers were identified, yet there was no overrepresentation in iRBD patients versus controls. Conclusion Our results do not support a major role for variants in these genes in the risk of iRBD. © 2020 International Parkinson and Movement Disorder Society

Objective Rapid eye movement sleep behavior disorder (RBD) is a prodromal synucleinopathy, as >80% will eventually convert to overt synucleinopathy. We performed an in‐depth analysis of the SNCA locus to identify RBD‐specific risk variants. Methods Full sequencing and genotyping of SNCA was performed in isolated/idiopathic RBD (iRBD, n = 1,076), Parkinson disease (PD, n = 1,013), dementia with Lewy bodies (DLB, n = 415), and control subjects (n = 6,155). The iRBD cases were diagnosed with RBD prior to neurodegeneration, although some have since converted. A replication cohort from 23andMe of PD patients with probable RBD (pRBD) was also analyzed (n = 1,782 cases; n = 131,250 controls). Adjusted logistic regression models and meta‐analyses were performed. Effects on conversion rate were analyzed in 432 RBD patients with available data using Kaplan–Meier survival analysis. Results A 5′‐region SNCA variant (rs10005233) was associated with iRBD (odds ratio [OR] = 1.43, p = 1.1E‐08), which was replicated in pRBD. This variant is in linkage disequilibrium (LD) with other 5′ risk variants across the different synucleinopathies. An independent iRBD‐specific suggestive association (rs11732740) was detected at the 3′ of SNCA (OR = 1.32, p = 4.7E‐04, not statistically significant after Bonferroni correction). Homozygous carriers of both iRBD‐specific SNPs were at highly increased risk for iRBD (OR = 5.74, p = 2E‐06). The known top PD‐associated variant (3′ variant rs356182) had an opposite direction of effect in iRBD compared to PD. Interpretation There is a distinct pattern of association at the SNCA locus in RBD as compared to PD, with an opposite direction of effect at the 3′ of SNCA . Several 5′ SNCA variants are associated with iRBD and with pRBD in overt synucleinopathies. ANN NEUROL 2020;87:584–598

AbstractBackgroundThe International Parkinson and Movement Disorders Society criteria for mild cognitive impairment in PD need validation. The objectives of this present study were to evaluate prognostic validity of level I (abbreviated) International Parkinson and Movement Disorders Society mild cognitive impairment in PD criteria for development of PD dementia and compared them with level II (comprehensive) criteria.MethodsWe analyzed data from 8 international studies (1045 patients) from our consortium that included baseline data on demographics, motor signs, depression, detailed neuropsychological testing, and longitudinal follow‐up for conversion to Parkinson's disease dementia. Survival analysis evaluated their contribution to the hazard of Parkinson's disease dementia.ResultsLevel I mild cognitive impairment in PD, increasing age, male sex, and severity of PD motor signs independently increased the hazard of Parkinson's disease dementia. Level I and level II mild cognitive impairment in PD classification had similar discriminative ability with respect to the time to Parkinson's disease dementia.ConclusionsLevel I mild cognitive impairment in PD classification independently contributes to the hazard of Parkinson's disease dementia. This finding supports the prognostic validity of the abbreviated mild cognitive impairment in PD criteria. © 2019 International Parkinson and Movement Disorder Society

Background: α-synuclein is a lead Parkinson’s disease (PD) biomarker. There are conflicting reports regarding accuracy of α-synuclein in different tissues and biofluids as a PD biomarker, and the within-subject anatomical distribution of α-synuclein is not well described. The Systemic Synuclein Sampling Study (S4) aims to address these gaps in knowledge. The S4 is a multicenter, cross-sectional, observational study evaluating α-synuclein in multiple tissues and biofluids in PD and healthy controls (HC). Objective: To describe the baseline characteristics of the S4 cohort and safety and feasibility of this study. Methods: Participants underwent motor and non-motor clinical assessments, dopamine transporter SPECT, biofluid collection (cerebrospinal fluid, saliva, and blood), and tissue biopsies (skin, sigmoid colon, and submandibular gland). Biopsy adequacy was determined based on presence of adequate target tissue. Tissue sections were stained with the 5C12 monoclonal antibody against unmodified α-synuclein. All specimens were acquired and processed in a standardized manner. Adverse events were systematically recorded. Results: The final cohort consists of 82 participants (61 PD, 21 HC). In 68 subjects (83%), all types of specimens were obtained but only 50 (61%) of subjects had all specimens both collected and evaluable for α-synuclein. Mild adverse events were common, especially for submandibular gland biopsy, but only 1 severe adverse event occurred. Conclusion: Multicenter tissue and biofluid sampling for α-synuclein is feasible and generally safe. S4 will inform understanding of the concurrent distribution of α-synuclein pathology and biomarkers in biofluids and peripheral nervous system in PD.

AbstractBackground: Numerous neuropsychological tests and test versions are used in Parkinson's disease research, but their relative capacity to detect mild cognitive deficits and their comparability across studies are unknown. The objective of this study was to identify neuropsychological tests that consistently detect cognitive decline in PD across studies.Methods: Data from 30 normed neuropsychological tests across 20 international studies in up to 2908 nondemented PD patients were analyzed. A subset of 17 tests was administered to up to 1247 healthy controls. A 2‐step meta‐analytic approach using standardized scores compared performance in PD with normative data.Results: Pooled estimates of the differences between PD and site‐specific healthy controls identified significant cognitive deficits in PD patients on 14 test scores across 5 commonly assessed cognitive domains (attention or working memory, executive, language, memory, and visuospatial abilities), but healthy control performance was statistically above average on 7 of these tests. Analyses based on published norms only, as opposed to direct assessment of healthy controls, showed high between‐study variability that could not be accounted for and led to inconclusive results.Conclusions: Normed neuropsychological tests across multiple cognitive domains consistently detect cognitive deficits in PD when compared with site‐specific healthy control performance, but relative PD performance was significantly affected by the inclusion and type of healthy controls versus the use of published norms only. Additional research is needed to identify a cognitive battery that can be administered in multisite international studies and that is sensitive to cognitive decline, responsive to therapeutic interventions, and superior to individual cognitive tests. © 2018 International Parkinson and Movement Disorder Society