Mutations in the SNCA gene, which encodes α-synuclein (α-syn), play a key role in the development of genetic Parkinson’s disease (PD). α-Syn is a major component of Lewy bodies in PD and glial cytoplasmic inclusions in multiple system atrophy (MSA). Rapid eye movement sleep behavior disorder patients often progress to PD, dementia with Lewy bodies, or MSA, which are collectively known as α-synucleinopathies. The loss of dopaminergic neurons with Lewy bodies precedes motor dysfunction in these diseases, but the mechanisms of neurodegeneration due to α-syn aggregation are poorly understood. Monitoring α-syn aggregation in vivo could serve as a diagnostic biomarker and help elucidate pathogenesis, necessitating a simple and accurate detection method. Seed amplification assays (SAAs), such as real-time quaking-induced conversion and protein misfolding cyclic amplification, are used to detect small amounts of abnormally structured α-syn protofibrils, which are central to aggregation. These methods are promising for the early diagnosis of α-synucleinopathy. Differences in α-syn filament structures between α-synucleinopathies, as observed through transmission electron microscopy and cryo-electron microscopy, suggest their role in the pathogenesis of neurodegeneration. SAAs may differentiate between subtypes of α-synucleinopathy and other diseases. Efforts are also being made to identify α-syn from blood using various methods. This review introduces body fluid α-syn biomarkers based on pathogenic α-syn seeds, which are expected to redefine α-synucleinopathy diagnosis and staging, improving clinical research accuracy and facilitating biomarker development.
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Objective To examine the inter- and intra-rater reliability of the pull test in patients with Parkinson’s disease (PD) using the extracted pull force.
Methods In this inter- and intra-rater reliability study, two raters performed a pull test on 30 patients with PD. The pull force was quantified using inertial sensors attached to the rater’s right hand and the patient’s lower trunk. In this study, the pull force was calculated as an extracted three-dimensional vector quantity, the resultant acceleration, and was expressed in m/s2. Inter- and intra-rater reliabilities were analyzed using the interclass correlation coefficient (ICC) for the pull force and Cohen’s weighted kappa (κw) for the pull test score. Furthermore, Bland–Altman analysis was used to investigate systematic errors.
Results The inter- and intra-rater reliability of the pull force was very poor (ICC = 0.033–0.214). Bland–Altman analysis revealed no systematic errors in the pull forces between the two test points. Conversely, κw for the pull test scores ranged from 0.763 to 0.920, indicating substantial to almost perfect agreement.
Conclusion The pull test score was reliable despite variations in the quantified pull force for inter- and intra-rater reliability. Our findings suggest that the pull test is a robust tool for evaluating postural instability in patients with PD and that the pull force probably does not affect scoring performance.
Objective Progressive supranuclear palsy (PSP) is a rare neurodegenerative disorder encompassing several phenotypes with various motor and cognitive deficits. We aimed to study motor and cognitive characteristics across PSP phenotypes and to assess the influence of apolipoprotein E (APOE) gene variants on PSP phenotypic expression.
Methods In this 20-year cross-sectional study, we retrospectively reviewed the charts of all patients classified as PSP patients and recategorized them according to phenotype using the Movement Disorder Society criteria (2017). Phenotypes were divided into three subgroups, Richardson’s syndrome (PSP-RS), PSP-cortical (PSP with predominant frontal presentation [PSP-F] + PSP with predominant speech/language disorder [PSP-SL] + PSP with predominant corticobasal syndrome [PSP-CBS]) and PSP-subcortical (PSP with predominant parkinsonism [PSP-P] + PSP with progressive gait freezing [PSP-PGF] + PSP with predominant postural instability [PSP-PI] + PSP with predominant ocular motor dysfunction [PSP-OM] + PSP with cerebellar ataxia [PSP-C] + PSP with primary lateral sclerosis [PSP-PLS]), based on clinical presentation during the first 3 years after symptom onset, which defines the early disease stage. Clinical and neuropsychological assessment data were collected. Genotyping of APOE was performed using restriction fragment length polymorphism polymerase chain reaction and verified by Sanger sequencing.
Results We included 112 PSP patients comprising 10 phenotypes classified into 48 PSP-RS, 34 PSP-cortical (PSP-CBS, 17.6%; PSP-F, 9.4%; PSP-SL, 8.2%) and 30 PSP-subcortical (PSP-P, 11.6%; PSP-PI, 8%; PSP-OM, 2.7%; PSP-PGF, 1.8%; PSP-C, 1.8%; PSP-PLS, 0.9%) subgroups. PSP-RS patients were older at disease onset (p = 0.009) and had more akinetic-rigid and levodopa-resistant parkinsonism (p = 0.006), while PSP-cortical patients had more tremors and asymmetric and/or levodopa-responsive parkinsonism (p = 0.025). Cognitive domains were significantly less altered in the PSP-subcortical subgroup. Overall, PSP-APOEε4 carriers developed parkinsonism earlier (p = 0.038), had earlier oculomotor dysfunction (p = 0.052) and had more altered cognitive profiles. The APOEε4 allele was also associated with a younger age of parkinsonism onset in the PSP-RS phenotype group (p = 0.026).
Conclusion This study demonstrated the wide phenotypic spectrum of PSP among Tunisians. Disease onset and akinetic-rigid and levodopa-resistant parkinsonism were the hallmarks of the PSP-RS phenotype, while milder cognitive impairment was characteristic of the PSP-subcortical subgroup. The APOEε4 allele was associated with earlier parkinsonism and oculomotor dysfunction and seemed to play a role in defining a more altered cognitive profile in PSP patients.
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Kyeongmin Baek, Young Min Kim, Han Kyu Na, Junki Lee, Dong Ho Shin, Seok-Jae Heo, Seok Jong Chung, Kiyong Kim, Phil Hyu Lee, Young H. Sohn, Jeehee Yoon, Yun Joong Kim
J Mov Disord. 2024;17(2):171-180. Published online February 13, 2024
Objective The Montreal Cognitive Assessment (MoCA) is recommended for general cognitive evaluation in Parkinson’s disease (PD) patients. However, age- and education-adjusted cutoffs specifically for PD have not been developed or systematically validated across PD cohorts with diverse education levels.
Methods In this retrospective analysis, we utilized data from 1,293 Korean patients with PD whose cognitive diagnoses were determined through comprehensive neuropsychological assessments. Age- and education-adjusted cutoffs were formulated based on 1,202 patients with PD. To identify the optimal machine learning model, clinical parameters and MoCA domain scores from 416 patients with PD were used. Comparative analyses between machine learning methods and different cutoff criteria were conducted on an additional 91 consecutive patients with PD.
Results The cutoffs for cognitive impairment decrease with increasing age within the same education level. Similarly, lower education levels within the same age group correspond to lower cutoffs. For individuals aged 60–80 years, cutoffs were set as follows: 25 or 24 years for those with more than 12 years of education, 23 or 22 years for 10–12 years, and 21 or 20 years for 7–9 years. Comparisons between age- and education-adjusted cutoffs and the machine learning method showed comparable accuracies. The cutoff method resulted in a higher sensitivity (0.8627), whereas machine learning yielded higher specificity (0.8250).
Conclusion Both the age- and education-adjusted cutoff methods and machine learning methods demonstrated high effectiveness in detecting cognitive impairment in PD patients. This study highlights the necessity of tailored cutoffs and suggests the potential of machine learning to improve cognitive assessment in PD patients.
Objective Huntington’s disease (HD) is an autosomal dominant, fully penetrant, neurodegenerative disease that most commonly affects middle-aged adults. HD is caused by a CAG repeat expansion in the HTT gene, resulting in the expression of mutant huntingtin (mHTT). Our aim was to detect and quantify mHTT in tear fluid, which, to our knowledge, has never been measured before.
Methods We recruited 20 manifest and 13 premanifest HD gene expansion carriers, and 20 age-matched controls. All patients underwent detailed assessments, including the Unified Huntington’s Disease Rating Scale (UHDRS) total motor score (TMS) and total functional capacity (TFC) score. Tear fluid was collected using paper Schirmer’s strips. The level of tear mHTT was determined using single-molecule counting SMCxPRO technology.
Results The average tear mHTT levels in manifest (67,223 ± 80,360 fM) and premanifest patients (55,561 ± 45,931 fM) were significantly higher than those in controls (1,622 ± 2,179 fM). We noted significant correlations between tear mHTT levels and CAG repeat length, “estimated years to diagnosis,” disease burden score and UHDRS TMS and TFC. The receiver operating curve demonstrated an almost perfect score (area under the curve [AUC] = 0.9975) when comparing controls to manifest patients. Similarly, the AUC between controls and premanifest patients was 0.9846. The optimal cutoff value for distinguishing between controls and manifest patients was 4,544 fM, whereas it was 6,596 fM for distinguishing between controls and premanifest patients.
Conclusion Tear mHTT has potential for early and noninvasive detection of alterations in HD patients and could be integrated into both clinical trials and clinical diagnostics.
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Unveiling brain disorders using liquid biopsy and Raman spectroscopy Jeewan C. Ranasinghe, Ziyang Wang, Shengxi Huang Nanoscale.2024; 16(25): 11879. CrossRef
Ocular tear fluid biomarkers collected by contact lenses Nikolay Boychev, Vincent Yeung, Menglu Yang, Levi N. Kanu, Amy E. Ross, Liangju Kuang, Lin Chen, Joseph B. Ciolino Biochemical and Biophysical Research Communications.2024; 734: 150744. CrossRef
Objective Exercise can improve both motor and nonmotor symptoms in people with Parkinson’s disease (PwP), but there is an unmet need for accessible and sustainable exercise options. This study aimed to evaluate the effect, feasibility, and safety of a regularly performed live-streaming tele-exercise intervention for PwP.
Methods A live-streaming exercise intervention for PwP was implemented twice a week for 12 weeks. We measured the motor and nonmotor symptom scores of the included patients before and after the intervention. Changes in clinical scores from baseline to postintervention were analyzed using paired t-tests. Factors associated with improvements in clinical scores and compliance were analyzed using Pearson’s correlation analysis.
Results Fifty-six participants were enrolled in the study. There were significant improvements in Hospital Anxiety and Depression Scale (HADS)-anxiety (p = 0.007), HADS-depression (p < 0.001), Unified Parkinson’s Disease Rating Scale (UPDRS) part III (p < 0.001), UPDRS total (p = 0.015), Hoehn and Yahr stage (p = 0.027), and Parkinson’s Disease Fatigue Scale-16 (p = 0.026) scores after the intervention. Improvements in motor symptoms were associated with improvements in mood symptoms and fatigue. Higher motor impairment at baseline was associated with a greater compliance rate and better postintervention composite motor and nonmotor outcomes (ΔUPDRS total score). Overall, the 12-week tele-exercise program was feasible and safe for PwP. No adverse events were reported. The overall adherence rate was 60.0% in our cohort, and 83.4% of the participants were able to participate in more than half of the exercise routines.
Conclusion The live-streaming tele-exercise intervention is a safe, feasible, and effective nonpharmacological treatment option that can alleviate fatigue and improve mood and motor symptoms in PwP.
Objective Hyperglycemia and diabetes mellitus have been identified as poor prognostic factors for motor and nonmotor outcomes in patients with Parkinson’s disease (PD), although there is some controversy with this finding. In the present study, we investigated the effects of fasting plasma glucose (FPG) levels on longitudinal motor and cognitive outcomes in PD patients.
Methods We included a total of 201 patients who were diagnosed with PD between January 2015 and January 2020. The patients were categorized based on FPG level into euglycemia (70 mg/dL < FPG < 100 mg/dL), intermediate glycemia (100 mg/dL ≤ FPG < 126 mg/dL), and hyperglycemia (FPG ≥ 126 mg/dL), and longitudinal FPG trajectories were analyzed using group-based trajectory modeling. Survival analysis was conducted to determine the time until motor outcome (Hoehn and Yahr stage ≥ 2) and the conversion from normal cognition to mild cognitive impairment.
Results Among the patient cohort, 82 had euglycemia, 93 had intermediate glycemia, and 26 had hyperglycemia. Intermediate glycemia (hazard ratio 1.747, 95% confidence interval [CI] 1.083–2.816, p = 0.0221) and hyperglycemia (hazard ratio 3.864, 95% CI 1.996–7.481, p < 0.0001) were found to be significant predictors of worsening motor symptoms. However, neither intermediate glycemia (hazard ratio 1.183, 95% CI 0.697–2.009, p = 0.5339) nor hyperglycemia (hazard ratio 1.297, 95% CI 0.601–2.800, p = 0.5078) demonstrated associations with the longitudinal progression of cognitive impairment. Diabetes mellitus, defined by self-reported medical history, was not related to poor motor or cognitive impairment outcomes.
Conclusion Our results suggest that both impaired glucose tolerance and hyperglycemia could be associated with motor progression in PD patients.
Objective Access to care for people with Parkinson’s disease (PD), particularly to device-aided therapies (DAT), is not equally distributed. The objective was to analyze accessibility to DAT (deep brain stimulation, intraduodenal levodopa pump therapy, and apomorphine pump therapy) in Poland.
Methods We analyzed the distribution of DAT use in Poland by determining the number of persons with PD receiving one of the three DATs during 2015–2021.
Results In 2021, the number of persons receiving DAT in Poland was 0.56% of the total PD population, increasing from 0.21% in 2015. Overall, deep brain stimulation was the preferred DAT in Poland, but strong regional differences in the use of the other DATs were observed. Accessibility to DAT was negatively associated with average annual income (p < 0.001).
Conclusion Access to DAT for persons with PD in Poland is still limited, and strong regional differences in accessibility were observed, although its general increase over the last decade is encouraging.
Lysosomal dysfunction plays an important role in neurodegenerative diseases, including Parkinson’s disease (PD) and possibly Parkinson-plus syndromes such as progressive supranuclear palsy (PSP). This role is exemplified by the involvement of variants in the GBA1 gene, which results in a deficiency of the lysosomal enzyme glucocerebrosidase and is the most frequently identified genetic factor underlying PD worldwide. Pathogenic variants in the SMPD1 gene are a recessive cause of Niemann–Pick disease types A and B. Here, we provide the first report on an association between a loss-of-function variant in the SMPD1 gene present in a heterozygous state (p.Pro332Arg/p.P332R, which is known to result in reduced lysosomal acid sphingomyelinase activity), with PSP-Richardson syndrome in three unrelated patients of Chinese ancestry.
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