Supranuclear Research Articles

Current Perspectives on Olfactory Loss in Atypical Parkinsonisms-A Review Article.

Atypical parkinsonisms (APs) present various symptoms including motor impairment, cognitive decline, and autonomic dysfunction. Olfactory loss (OL), being a significant non-motor symptom, has emerged as an under-evaluated, yet potentially valuable, feature that might aid in the differential diagnosis of APs. The most pronounced OL is usually associated with Dementia with Lewy Bodies (DLB). While the view about the normosmic course of Multiple System Atrophy (MSA) remains unchanged, research indicates that mild OL may occur in a subset of patients with Progressive Supranuclear Palsy (PSP) and Corticobasal Degeneration (CBD). This might be linked to the deposition of abnormal protein aggregates in the central nervous system. The aim of this review is to discuss the role of OL and its degree and pattern in the pathogenesis and course of APs. Olfactory testing could serve as a non-invasive, quick screening tool to differentiate between APs and project disease progression. There is a need for further evaluation of this topic. This may lead to the development of standardized olfactory testing protocols that could be implemented in clinical practice, making differential diagnosis of APs more convenient. Understanding differences in the sense of smell could create an avenue for more targeted therapeutic strategies.

The possible connection between neutrophil-to-high-density lipoprotein ratio and cerebral perfusion in clinically established corticobasal syndrome: a pilot study.

Progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS) are tauopathic atypical parkinsonisms. Given their overlap in terms of clinical manifestation, there is growing interest in the mechanisms leading to these entities. In total, 71 patients were included in the study, 19 of whom were clinically diagnosed with CBS, 37 with PSP, and 15 with Parkinson's disease (PD). The mean ages of the participants were 72.8, 72.9, and 64.0 years, respectively, and the disease duration varied from 3 to 6 years. Each individual underwent blood collection. Morphological and biochemical evaluation of blood samples was performed to analyze the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and neutrophil-to-high-density lipoprotein ratio (NHR). A single-photon emission computed tomography (SPECT) with technetium-99m hexamethylpropyleneamine oxime (99Tc-HMPAO) tracer was used to assess perfusion in two regions of interest (ROI): the thalamus and insula. Using Pearson correlation to assess the linear relationship between NHR and perfusion in the insula and thalamus for CBS, PSP, and PD patients, the authors intended to verify possible correlations between NLR, PLR, and NHR and perfusion in the indicated ROIs. The study revealed a negative linear correlation between NHR and perfusion of both the left (Insula L; R = -0.59) and right (Insula R; R = -0.58) insula regions. Similar to the insula, a linear correlation between NHR and activity in both the left (Thalamus L) and right (Thalamus R) thalamus regions in CBS subjects with a relatively stronger correlation in the right thalamus (R = -0.64 vs. R = -0.58) was found. These observations were not confirmed in PSP and PD patients. Simultaneously using non-specific parameters for peripheral inflammation (NLR, PLR, and NHR) and perfusion, SPECT may be an interesting beginning point for further analysis of inflammatory disease mechanisms. To the best of our knowledge, this is the first study to address the potential correlation between the peripheral neuroinflammatory markers NLR, PLR, and NHR and perfusion disturbances in particular ROIs.

Toward an animal model of Progressive Supranuclear Palsy.

Progressive Supranuclear Palsy (PSP) is a rare and fatal neurodegenerative tauopathy which, with a rapid clinical progression coupled to a strong degree of clinico-pathologic correlation, has been suggested to be a "frontrunner" in translational development for neurodegenerative proteinopathies. Elegant studies in animals have contributed greatly to our understanding of disease pathogenesis in PSP. However, presently no animal model replicates the key anatomical and cytopathologic hallmarks, the spatiotemporal spread of pathology, progressive neurodegeneration, or locomotor and cognitive symptoms that characterize PSP. Current models therefore likely fail to recapitulate the key mechanisms that underly the pathological progression of PSP, impeding their translational value. Here we review what we have learned about PSP from work in animals to date, examine the gaps in modeling the disease and discuss strategies for the development of refined animal models that will improve our understanding of disease pathogenesis and provide a critical platform for the testing of novel therapeutics for this devastating disease.

Monocyte to high-density lipoprotein cholesterol ratio reflects the peripheral inflammatory state in parkinsonian disorders

BackgroundIn Parkinson’s disease (PD) and Parkinson plus syndrome (PPS), inflammation is recognized as a relevant or contributing factor in the advancement of the diseases. For this reason, numerous biomarkers signaling immune alteration in both the central and peripheral nervous systems have been evaluated in PD and PPS. Nonetheless, the comprehensive inflammatory indices derived from readily available standard blood tests in PD, PPS, and healthy controls (HC) were rarely evaluated especially in the early stage of the diseases. ObjectiveThe aim of this study is to explore the serum level of peripheral inflammatory markers among the patients and investigate whether these markers contribute to symptoms. MethodClinical data and blood test results from drug naïve, early-stage 139 PD and 87 PPS patients, along with 139 age- and sex-matched healthy controls (HC) to PD were enrolled, with exclusion criteria applied to conditions potentially affecting inflammation. The study examined the disparities in peripheral inflammation among the groups, using total and subpopulation of white blood cells (WBCs), platelet count, red cell distribution width (RDW), high-density lipoprotein cholesterol (HDL-C), and other composite values reflecting inflammation including RDW to platelet ratio (RPR), neutrophil to lymphocyte ratio (NLR), monocyte to lymphocyte ratio (MLR), platelet to lymphocyte ratio (PLR), neutrophil to HDL-C ratio (NHR), monocyte to HDL-C ratio (MHR), lymphocyte to HDL-C ratio (LHR), platelet to HDL-C ratio (PHR), systemic inflammation index (SII), systemic inflammation response index (SIRI), and aggregate index of systemic inflammation (AISI). ResultThe MHR values were significantly higher in both PD and PPS groups compared to HC (p < 0.001), and NHR was significantly higher in the PPS group only compared to the HC group (p < 0.001). However, no significant differences in all the inflammatory markers were observed between PPS and PD (p > 0.05). Subgroup analysis of progressive supranuclear palsy (PSP) and multiple system atrophy (MSA) patients revealed significantly higher NHR and MHR levels compared to the HC group (p = 0.025, p = 0.050, respectively), with no significant difference among PSP, MSA, and PD groups. After adjustment for age, sex, and disease duration, MHR was positively associated with H&Y in the total population (β = 0.288, p < 0.001), negatively associated with MMSE in the PD group (β = −0.245, p = 0.017), and positively associated with both H&Y (β = 0.432, p < 0.001) and UPDRS part II (β = 0.295, p = 0.018) in PPS group. ConclusionNHR and MHR values are not effective as reliable diagnostic markers due to overlap among groups and their limited discriminative capacity in ROC analyses. However, MHR may potentially serve as an indicator reflecting peripheral inflammation in the early stage of PD and PPS compared to HC.

Beyond Vertical: Unraveling The PSP Enigma

Progressive Supranuclear Palsy (PSP) is an aberrant type of Parkinsonian disorder that cognates with progressive axial rigidity, vertical gaze palsy, dysarthria and dysphagia. It is supposed to affect movement, gait, balance, speech, swallowing, vision, movements, mood, behavior and cognition. PSP increases as per age and its prevalence is 7% per 1 lakh, as reported. PSP is often misdiagnosed with Parkinson’s disease, however, PSP progresses more rapidly than Parkinson’s. people with PSP develop unique eye movement problems with looking up and down, speech and swallowing problems are much more common and severe in PSP than PD, leaning backwards and extend their neck in PSP (axial rigidity) while in PD -bending happens in forward direction than backward. Tremors are rare for PSP but very common in PD. The three most important primary motor symptoms are: tremors, bradykinesia, and rigidity (parkinsonism). Since this disease is termed as tauopathy, 4R-tau isoforms aggregate into straight filaments and appear as a major tau doublet (tau64 &amp; 69). The differential diagnosis is very difficult for PSP because many neurodegenerative disorders have similar symptoms and very less discrimination between PSP and other disorders. The main objective of our study is to create awareness about PSP and its overlapping symptoms with PD as well as other and other neuro-degenerative disorders. However, based upon detailed investigations about, tau and its isoforms, these clinical features may be distinguished. However, it would require abundant knowledge of the molecular functioning and structure of tau proteins. Keywords: tauopathy, parkinsonism, progressive axial rigidity, neuro-degenerative disorders

Davunetide sex-dependently boosts memory in prodromal Alzheimer’s disease

BackgroundThe tauopathy inhibitor, davunetide shows sex-dependent efficacy in women suffering from progressive supranuclear palsy. Extending these findings to prodromal Alzheimer’s disease, we submitted a double-blind, placebo-controlled, 12 weeks/16 weeks follow-up, davunetide clinical trial results in amnestic mild cognitive impairment (ClinicalTrials.gov ID NCT00422981), to a sex-dependent analysis.MethodsOne hundred forty-four individuals, separated into eight groups (1:2 placebo—and 2 doses, 5 mg davunetide/daily or 15 mg davunetide/twice-daily, with matching placebo intranasal volumes), were evaluated.ResultsSignificant dose-dependent cognitive increases were observed in men compared to women with a test of delayed (12 ss) visual matching to the sample. In a test of semantic working memory and attention (digit span), women showed a significant low-dose placebo effect, ensuing in a high dose significant davunetide improvement, over the matched placebo. Correlating anxiety with cognition showed sex-opposing results, with women depicting significant anxiety correlations with delayed matching to sample.DiscussionIn conclusion, sex-specific prodromal Alzheimer’s drug development is encouraged, with davunetide playing a lead initiative role.

Identification of Genetic Variants in Progressive Supranuclear Palsy in Southeast Asia.

Progressive supranuclear palsy (PSP) is largely a sporadic disease with few reported familial cases. Genome-wide association studies (GWAS) in sporadic PSP in Caucasian populations have identified MAPT as the most commonly associated genetic risk locus with the strongest effect size. At present there are limited data on genetic factors associated with PSP in Asian populations. Our goal was to investigate the genetic factors associated with PSP in Southeast Asian PSP patients. Next-generation sequencing (whole-exome, whole-genome and targeted sequencing) was performed in two Asian cohorts, comprising 177 PSP patients. We identified 17 pathogenic or likely pathogenic variants in 16 PSP patients (9%), eight of which were novel. The most common relevant genetic variants identified were in MAPT, GBA1, OPTN, SYNJ1, and SQSTM1. Other variants detected were in TBK1, PRNP, and ABCA7-genes that have been implicated in other neurodegenerative diseases. Eighteen patients had a positive family history, of whom two carried pathogenic MAPT variants, and one carried a likely pathogenic GBA1 variant. None of the patients had expanded repeats in C9orf72. Furthermore, we found 16 different variants of uncertain significance in 21 PSP patients in PSEN2, ABCA7, SMPD1, MAPT, ATP13A2, OPTN, SQSTM1, CYLD, and BSN. The genetic findings in our PSP cohorts appear to be somewhat distinct from those in Western populations, and also suggest an overlap of the genetic architecture between PSP and other neurodegenerative diseases. Further functional studies and validation in independent Asian cohorts will be useful for improving our understanding of PSP genetics and guiding genetic screening strategies in these populations. © 2024 International Parkinson and Movement Disorder Society.

Visual reading for [18F]Florzolotau Tau PET scans in progressive supranuclear palsy.

The identification of tau accumulation within living brains holds significant potential in facilitating accurate diagnosis of progressive supranuclear palsy (PSP). While visual assessment is frequently employed, standardized methods for tau positron emission tomography (PET) specifically in PSP are absent. We aimed to develop a visual reading algorithm dedicated to the evaluation of [18F]Florzolotau PET in PSP. 148 PSP and 30 healthy volunteers were divided into a development set (for the establishment of the reading rules; n = 89) and a testing set (for the validation of the reading rules; n = 89). For differential diagnosis, 55 α-synucleinopathies were additionally included into the testing set. The visual reading method was established by an experienced assessor (Reader 0) and was then validated by Reader 0 and two additional readers on regional and overall binary manners. A positive binding in both midbrain and globus pallidus/putamen regions was characterized as a PSP-like pattern, whereas any other pattern was classified as non-PSP-like. Reader 1 (94.4%) and Reader 2 (93.8%) showed excellent agreement for the overall binary determination against Reader 0. The regional binary determinations of midbrain and globus pallidus/putamen showed excellent agreement among readers (kappa > 0.80). The overall binary evaluation demonstrated reproducibility of 86.1%, 94.4% and 77.8% for three readers. The visual reading algorithm showed high agreement with regional standardized uptake value ratios and clinical diagnoses. Through the application of the suggested visual reading algorithm, [18F]Florzorotau PET imaging demonstrated a robust performance for the imaging diagnosis of PSP.

Rapid Eye Movements during REM Sleep Differentiate PSP from Parkinson's Disease.

Little is known about the characteristics and occurrence frequencies of rapid eye movements (REMs) during REM sleep in movement disorders. The aim of this study was to detect and characterize REMs during polysomnographically defined REM sleep as recorded by electro-oculography (EOG) in 12 patients with progressive supranuclear palsy (PSP), 13 patients with Parkinson's disease (PD) and 12 healthy controls. Using a modified EOG montage, we developed an algorithm that automatically detects and characterizes REMs during REM sleep based on their presumptive saccadic kinematics. Compared to PD and healthy controls, REM densities and REM peak velocities were significantly reduced in PSP. These effects were most pronounced in vertical REMs. Ocular motor dysfunction, one of the cardinal features of PSP, seems to be equally at play during REM sleep and wakefulness. For future studies, we provide a novel tool for the unbiased analysis of REMs during REM sleep in movement disorders.

SEND-PD in Parkinsonian Syndromes: Results of a Monocentric Cross-Sectional Study.

Neuropsychiatric symptoms in particular impair health-related quality of life (QoL) of patients with Parkinson's disease and atypical Parkinsonian syndromes. For this reason, various scales have been developed for detection of neuropsychiatric symptoms, such as the Scale for evaluation of neuropsychiatric disorders in Parkinson's disease (SEND-PD). First, the objective of this study was to explore the interrelation between the SEND-PD and clinical parameters in patients with Parkinson's disease and thus confirm its validity. In addition, the applicability in a well-defined cohort of patients with atypical Parkinsonian syndromes was investigated for the very first time. A clinically well-defined cohort of 122 patients with Parkinson's disease (PD), 55 patients with Progressive Supranuclear Palsy (PSP) and 33 patients with Multiple System Atrophy (MSA) were analyzed. First, the SEND-PD was correlated with established disease-specific scores in patients with PD. Next, the results of the SEND-PD were compared between the different Parkinsonian syndromes. The SEND-PD showed a strong significant correlation with several scores, especially the UPDRS I (Rho = 0.655) and GDS-15 (Rho = 0.645). Depressive burden was significantly higher in MSA patients in comparison to the PD patient cohort (PD, 3.8 ± 3.3; MSA, 5.45 ± 3.87), while PSP patients showed significantly less psychotic (PD 1.6 ± 2.1; PSP 0.6 ± 0.9) and impulse control disorders (PD 0.3 ± 1.0; PSP 0.02 ± 0.1). The SEND-PD is a useful, brief and highly applicable screening tool for neuropsychiatric symptoms in PD, but not in atypical Parkinsonism, as their unique neuropsychiatric symptom composition is not fully captured.

Combining cerebrospinal fluid and PI-2620 tau-PET for biomarker-based stratification of Alzheimer's disease and 4R-tauopathies.

Recent advances in biomarker research have improved the diagnosis and monitoring of Alzheimer's disease (AD), but in vivo biomarker-based workflows to assess 4R-tauopathy (4RT) patients are currently missing. We suggest a novel biomarker-based algorithm to characterize AD and 4RTs. We cross-sectionally assessed combinations of cerebrospinal fluid measures (CSF p-tau181 and t-tau) and 18F-PI-2620 tau-positron emission tomography (PET) in patients with AD (n=64), clinically suspected 4RTs (progressive supranuclear palsy or corticobasal syndrome, n=82) and healthy controls (n=19). Elevated CSF p-tau181 and cortical 18F-PI-2620 binding was characteristic for AD while normal CSF p-tau181 with elevated subcortical 18F-PI-2620 binding was characteristic for 4RTs. 18F-PI-2620-assessed posterior cortical hypoperfusion could be used as an additional neuronal injury biomarker in AD. The specific combination of CSF markers and 18F-PI-2620 tau-PET in disease-specific regions facilitates the biomarker-guided stratification of AD and 4RTs. This has implications for biomarker-aided diagnostic workflows and the advancement in clinical trials. Novel biomarker-based algorithm for differentiating AD and 4R-tauopathies. A combination of CSF p-tau181 and 18F-PI-2620 discriminates AD versus 4R tauopathies. Hypoperfusion serves as an additional neuronal injury biomarker in AD.

HnRNP A1, hnRNP A2B1, and hnRNP K are dysregulated in tauopathies, but do not colocalize with tau pathology.

Tau interacts with multiple heterogeneous nuclear ribonucleoproteins (hnRNPs)-a family of RNA binding proteins that regulate multiple known cellular functions, including mRNA splicing, mRNA transport, and translation regulation. We have previously demonstrated particularly significant interactions between phosphorylated tau and three hnRNPs (hnRNP A1, hnRNP A2B1, and hnRNP K). Although multiple hnRNPs have been previously implicated in tauopathies, knowledge of whether these hnRNPs colocalize with tau aggregates or show cellular mislocalization in disease is limited. Here, we performed a neuropathological study examining the colocalization between hnRNP A1, hnRNP A2B1, hnRNP K, and phosphorylated tau in two brain regions (hippocampus and frontal cortex) in six disease groups (Alzheimer's disease, mild cognitive impairment, progressive supranuclear palsy, corticobasal degeneration, Pick's disease, and controls). Contrary to expectations, hnRNP A1, hnRNP A2B1, and hnRNP K did not colocalize with AT8-immunoreactive phosphorylated tau pathology in any of the tauopathies examined. However, we did observe significant cellular mislocalization of hnRNP A1, hnRNP A2B1 and hnRNP K in tauopathies, with unique patterns of mislocalization observed for each hnRNP. These data point to broad dysregulation of hnRNP A1, A2B1 and K across tauopathies with implications for disease processes and RNA regulation.

454P Myotonic dystrophy type 1 with progressive supranuclear palsy showing responsiveness to levodopa

454P Myotonic dystrophy type 1 with progressive supranuclear palsy showing responsiveness to levodopa

Clinical approach to probable mixed vascular dementia and progressive supranuclear palsy

Probable mixed dementia, combining vascular dementia and progressive supranuclear palsy (PSP), presents diagnostic challenges due to overlapping clinical features and radiological findings. This case report highlights the complexities involved in diagnosing such cases, where clinical manifestations evolve, requiring careful evaluation and periodic reassessment. Imaging plays a crucial role, with characteristic features aiding in distinguishing between different etiologies. Management of mixed dementia poses therapeutic dilemmas, particularly given the lack of effective treatments for PSP. Nonetheless, a comprehensive approach involving education, vascular risk factor control, and family support is essential for optimizing long-term patient and caregiver outcomes. This case underscores the importance of a multidisciplinary clinical and radiological approach in navigating the complexities of mixed dementia cases.

Acute Levodopa Challenge in Atypical Parkinsonism: Comprehensive Analysis of Individual Motor Responses.

The acute levodopa challenge is widely used to distinguish Parkinson's disease (PD) from atypical parkinsonian syndromes (APSs) such as multiple system atrophy (MSA) and progressive supranuclear palsy (PSP). In APSs, very few patients present a clinically relevant response to levodopa. The aim of this study was to determine whether patients with atypical parkinsonism benefit from levodopa in any aspect of their multiple motor deficits despite the generally poor response. This retrospective study analyzed individual motor responses to the acute levodopa challenge using the MDS-UPDRS III in 47 PSP, 26 MSA, and 71 PD patients at Hannover Medical School. Despite the generally poor levodopa response in both PSP and MSA patients, bradykinesia and rigidity were the symptoms most notably affected by levodopa in PSP patients, while MSA patients experienced significant improvements in bradykinesia and action tremor. These findings underscore the variability in levodopa response among PSP and MSA patients and highlight the need for personalized treatment approaches in atypical parkinsonism.

Legumain/asparaginyl endopeptidase-resistant tau fibril fold produces corticobasal degeneration-specific C-terminal tau fragment

Corticobasal degeneration (CBD) is a major four-repeat tauopathy along with progressive supranuclear palsy (PSP). Although detergent-insoluble 37–40-kDa carboxyl-terminal tau fragments (CTFs) are hallmarks of CBD pathology, the process of their formation is unknown. This study monitored the formation of CBD-type fibrils that exhibit astrocytic plaques, a characteristic CBD pathology, using its biochemical properties different from those of Alzheimer's disease/PSP-type fibrils. Tau fibrils from patients with CBD were amplified in non-astrocytic cultured cells, which maintained CBD-specific biochemical properties. We found that the lysosomal protease Legumain (LGMN) was involved in the generation of CBD-specific 37–40-kDa CTFs. While LGMN cleaved tau fibrils at Asn167 and Asn368 in the brain tissues of patients with Alzheimer's disease and PSP, tau fibrils from patients with CBD were predominantly resistant to cleavage at Asn368 by LGMN, resulting in the generation of CBD-specific CTFs. LGMN preference in tau fibrils was lost upon unraveling the tau fibril fold, suggesting that the CBD-specific tau fibril fold contributes to CBD-specific CTF production. From these findings, we found a way to differentiate astrocytic plaque from tufted astrocyte using the anti-Asn368 LGMN cleavage site-specific antibody. Inoculation of tau fibrils amplified in non-astrocytic cells into the mouse brain reproduced LGMN-resistant tau fibrils and recapitulated anti-Asn368-negative astrocytic plaques, which are characteristic of CBD pathology. This study supports the existence of disease-specific tau fibrils and contribute to further understanding of the tauopathy diagnosis. Our tau propagation mouse model using cellular tau seeds may contribute to uncovering disease mechanisms and screening for potential therapeutic compounds.

Establishing a Specialist Physiotherapy service with a Regional Specialist Memory Clinic

Abstract Background Patients with complex motor-cognitive syndromes (E.g. Dementia with Lewy Bodies, Corticobasal syndrome, Progressive Supranuclear Palsy and Huntington’s disease) present with a wide variety of symptoms. Accordingly, these patients have traditionally been managed under different services from Neurology-led movement disorder clinics to age-related services, without dedicated access to specialist physiotherapy input. Recognising this, the Model of Care for Dementia in Ireland recommended that all regional specialist memory services (RSMC) should have a dedicated Clinical Specialist Physiotherapist. The aim of this study was to provide an overview of clinic activity in the first six months of operation. Methods Physiotherapy referrals were collected from September 2023 to March 2024. Referral details were captured using Microsoft Excel and included patient demographics, reason for referral, diagnosis and previous physiotherapy input. Following triage of referrals, patients were placed in one of the following three care pathways: Results 63 referrals were generated. Of these, 15 patients were referred for pre-diagnostic assessment, 46 were referred for rehabilitation, and 2 were referred for secondary prevention. Of those referred for rehabilitation; 18 patients had a diagnosis of DLB, 27 had another form of atypical Parkinsonism, 1 patient had HD. 22 patients had previous physiotherapy input. Conclusion This is the first specialist physiotherapy service in Ireland within a RSMC. This presents a challenge as there is no specific physiotherapy care pathway established for this service elsewhere, but also opportunity for service development and innovation. This overview will help with strategic and service planning and enables KPIs to be established to ensure patients receive a quality service.

Biomarker discovery in progressive supranuclear palsy from human cerebrospinal fluid

BackgroundProgressive supranuclear palsy (PSP) is a neurodegenerative disorder often misdiagnosed as Parkinson’s Disease (PD) due to shared symptoms. PSP is characterized by the accumulation of tau protein in specific brain regions, leading to loss of balance, gaze impairment, and dementia. Diagnosing PSP is challenging, and there is a significant demand for reliable biomarkers. Existing biomarkers, including tau protein and neurofilament light chain (NfL) levels in cerebrospinal fluid (CSF), show inconsistencies in distinguishing PSP from other neurodegenerative disorders. Therefore, the development of new biomarkers for PSP is imperative.MethodsWe conducted an extensive proteome analysis of CSF samples from 40 PSP patients, 40 PD patients, and 40 healthy controls (HC) using tandem mass tag-based quantification. Mass spectrometry analysis of 120 CSF samples was performed across 13 batches of 11-plex TMT experiments, with data normalization to reduce batch effects. Pathway, interactome, cell-type-specific enrichment, and bootstrap receiver operating characteristic analyses were performed to identify key candidate biomarkers.ResultsWe identified a total of 3,653 unique proteins. Our analysis revealed 190, 152, and 247 differentially expressed proteins in comparisons of PSP vs. HC, PSP vs. PD, and PSP vs. both PD and HC, respectively. Gene set enrichment and interactome analysis of the differentially expressed proteins in PSP CSF showed their involvement in cell adhesion, cholesterol metabolism, and glycan biosynthesis. Cell-type enrichment analysis indicated a predominance of neuronally-derived proteins among the differentially expressed proteins. The potential biomarker classification performance demonstrated that ATP6AP2 (reduced in PSP) had the highest AUC (0.922), followed by NEFM, EFEMP2, LAMP2, CHST12, FAT2, B4GALT1, LCAT, CBLN3, FSTL5, ATP6AP1, and GGH.ConclusionBiomarker candidate proteins ATP6AP2, NEFM, and CHI3L1 were identified as key differentiators of PSP from the other groups. This study represents the first large-scale use of mass spectrometry-based proteome analysis to identify cerebrospinal fluid (CSF) biomarkers specific to progressive supranuclear palsy (PSP) that can differentiate it from Parkinson’s disease (PD) and healthy controls. Our findings lay a crucial foundation for the development and validation of reliable biomarkers, which will enhance diagnostic accuracy and facilitate early detection of PSP.

Asymmetry in Atypical Parkinsonian Syndromes—A Review

Background/Objectives: Atypical parkinsonian syndromes (APSs) are a group of neurodegenerative disorders that differ from idiopathic Parkinson’s disease (IPD) in their clinical presentation, underlying pathology, and response to treatment. APSs include conditions such as multiple system atrophy (MSA), progressive supranuclear palsy (PSP), corticobasal syndrome (CBS), and dementia with Lewy bodies (DLB). These disorders are characterized by a combination of parkinsonian features and additional symptoms, such as autonomic dysfunction, supranuclear gaze palsy, and asymmetric motor symptoms. Many hypotheses attempt to explain the causes of neurodegeneration in APSs, including interactions between environmental toxins, tau or α-synuclein pathology, oxidative stress, microglial activation, and vascular factors. While extensive research has been conducted on APSs, there is a limited understanding of the symmetry in these diseases, particularly in MSA. Neuroimaging studies have revealed metabolic, structural, and functional abnormalities that contribute to the asymmetry in APSs. The asymmetry in CBS is possibly caused by a variable reduction in striatal D2 receptor binding, as demonstrated in single-photon emission computed tomography (SPECT) examinations, which may explain the disease’s asymmetric manifestation and poor response to dopaminergic therapy. In PSP, clinical dysfunction correlates with white matter tract degeneration in the superior cerebellar peduncles and corpus callosum. MSA often involves atrophy in the pons, putamen, and cerebellum, with clinical symmetry potentially depending on the symmetry of the atrophy. The aim of this review is to present the study findings on potential symmetry as a tool for determining potential neuropsychological disturbances and properly diagnosing APSs to lessen the misdiagnosis rate. Methods: A comprehensive review of the academic literature was conducted using the medical literature available in PubMed. Appropriate studies were evaluated and examined based on patient characteristics and clinical and imaging examination outcomes in the context of potential asymmetry. Results: Among over 1000 patients whose data were collected, PSP-RS was symmetrical in approximately 84% ± 3% of cases, with S-CBD showing similar results. PSP-P was symmetrical in about 53–55% of cases, while PSP-CBS was symmetrical in fewer than half of the cases. MSA-C was symmetrical in around 40% of cases. It appears that MSA-P exhibits symmetry in about 15–35% of cases. CBS, according to the criteria, is a disease with an asymmetrical clinical presentation in 90–99% of cases. Similar results were obtained via imaging methods, but transcranial sonography produced different results. Conclusions: Determining neurodegeneration symmetry may help identify functional deficits and improve diagnostic accuracy. Patients with significant asymmetry in neurodegeneration may exhibit different neuropsychological symptoms based on their individual brain lateralization, impacting their cognitive functioning and quality of life.

CSF α-Synuclein Seed Amplification Assay in Patients With Atypical Parkinsonian Disorders.

There is no disease-modifying treatment of corticobasal syndrome (CBS) and progressive supranuclear palsy (PSP), 2 disorders characterized by their striking phenotypic, and, in CBS, pathologic heterogeneity. Seed amplification assays (SAAs) could enable the detection of neuropathologic processes, such as α-synuclein (αSyn) copathology, that affect the success of future disease-modifying treatment strategies. The primary objective was to assess possible αSyn copathology in CBS and PSP, as detected in CSF using an αSyn SAA (αSyn-SAA). Secondary objectives were to evaluate the association of αSyn-SAA positivity with other biomarkers including of Alzheimer disease (AD), and with clinical presentation. We hypothesized that αSyn-SAA positivity would be detectable in CBS and PSP and that it would be associated with AD biomarker positivity and β-amyloid (Aβ) 42 levels, neurodegeneration as assessed by neurofilament light chain (NfL) levels, and symptoms associated with synucleinopathies. This cross-sectional observational study included patients clinically diagnosed with CBS and PSP who underwent a lumbar puncture between 2012 and 2021 (Toronto Western Hospital, Canada). CSF was tested for αSyn-SAA positivity, AD biomarkers, and NfL levels. Clinical data were derived from medical records. We tested the CSF of 40 patients with CBS (19 female patients, 65.9 ± 8.6 years) and 28 with PSP (13 female patients, 72.5 ± 8.7 years old), mostly White (n = 50) or Asian (n = 14). αSyn-SAA positivity was observed in 35.9% patients with CBS and 28.6% with PSP. In young-onset, but not late-onset patients, αSyn-SAA positivity and AD positivity were associated (odds ratio [OR] 8.8, 95% CI 1.2-82.6, p < 0.05). A multivariable linear regression analysis showed a significant interaction of αSyn-SAA status by age at onset on CSF Aβ42 levels (β = 0.3 ± 0.1, p < 0.05). Indeed, age at onset was positively related to Aβ42 levels only in αSyn-SAA-positive patients, as shown by slope comparison. A logistic regression analysis also suggested that REM sleep behavior disorder was associated with αSyn-SAA positivity (OR 60.2, 95% CI 5.2-1,965.8; p < 0.01). We detected a frequency of αSyn-SAA positivity in CBS and PSP in line with pathologic studies, highlighting the usefulness of SAAs for in vivo detection of otherwise undetectable neuropathologic processes. Our results also suggest that AD status (specifically low Aβ42) and older age at onset may contribute to αSyn-SAA positivity. This opens new perspectives for the stratification of patients in clinical trials.