Second consensus statement on the diagnosis of multiple system atrophy

Plasma circulating cell-free DNA integrity and relative telomere length as diagnostic biomarkers for Parkinson's disease and multiple system atrophy: a cross-sectional study

JOURNAL/nrgr/04.03/01300535-202512000-00025/figure1/v/2025-01-31T122243Z/r/image-tiff In clinical specialties focusing on neurological disorders, there is a need for comprehensive and integrated non-invasive, sensitive, and specific testing methods. Both Parkinson's disease and multiple system atrophy are classified as α-synucleinopathies, characterized by abnormal accumulation of α-synuclein protein, which provides a shared pathological background for their comparative study. In addition, both Parkinson's disease and multiple system atrophy involve neuronal death, a process that may release circulating cell-free DNA (cfDNA) into the bloodstream, leading to specific alterations. This premise formed the basis for investigating cell-free DNA as a potential biomarker. Cell-free DNA has garnered attention for its potential pathological significance, yet its characteristics in the context of Parkinson's disease and multiple system atrophy are not fully understood. This study investigated the total concentration, nonapoptotic level, integrity, and cell-free DNA relative telomere length of cell-free DNA in the peripheral blood of 171 participants, comprising 76 normal controls, 62 patients with Parkinson's disease, and 33 patients with multiple system atrophy. In our cohort, 75.8% of patients with Parkinson's disease (stage 1-2 of Hoehn & Yahr) and 60.6% of patients with multiple system atrophy (disease duration less than 3 years) were in the early stages. The diagnostic potential of the cell-free DNA parameters was evaluated using receiver operating characteristic (ROC) analysis, and their association with disease prevalence was examined through logistic regression models, adjusting for confounders such as age, sex, body mass index, and education level. The results showed that cell-free DNA integrity was significantly elevated in both Parkinson's disease and multiple system atrophy patients compared with normal controls ( P < 0.001 for both groups), whereas cell-free DNA relative telomere length was markedly shorter ( P = 0.003 for Parkinson's disease and P = 0.010 for multiple system atrophy). Receiver operating characteristic analysis indicated that both cell-free DNA integrity and cell-free DNA relative telomere length possessed good diagnostic accuracy for differentiating Parkinson's disease and multiple system atrophy from normal controls. Specifically, higher cell-free DNA integrity was associated with increased risk of Parkinson's disease (odds ratio [OR]: 5.72; 95% confidence interval [CI]: 1.54-24.19) and multiple system atrophy (OR: 10.10; 95% CI: 1.55-122.98). Conversely, longer cell-free DNA relative telomere length was linked to reduced risk of Parkinson's disease (OR: 0.16; 95% CI: 0.04-0.54) and multiple system atrophy (OR: 0.10; 95% CI: 0.01-0.57). These findings suggest that cell-free DNA integrity and cell-free DNA relative telomere length may serve as promising biomarkers for the early diagnosis of Parkinson's disease and multiple system atrophy, potentially reflecting specific underlying pathophysiological processes of these neurodegenerative disorders.

Synaptic Density Reductions in MSA: A Potential Biomarker Identified Through [18F]SynVesT-1 PET Imaging

OBJECTIVE

The objective of this study was to delineate synaptic density alterations in multiple system atrophy (MSA) and explore its potential role as a biomarker for MSA diagnosis and disease severity monitoring using [18F]SynVesT-1 positron emission tomography / computed tomography (PET CT).

METHODS

In this prospective study, 60 patients with MSA (30 patients with MSA-parkinsonian [MSA-P] subtype and 30 patients with MSA-cerebellar [MSA-C] subtype), 30 patients with Parkinson's disease (PD), and 30 age-matched healthy controls (HCs) underwent [18F]SynVesT-1 PET/CT for synaptic density assessment. Visual, voxel, and volumetric region of interest (VOI) analyses were used to elucidate synaptic density patterns in the MSA brain and establish diagnostic criteria. The diagnostic performances of both visual and VOI-based diagnostics were evaluated using receiver operating characteristic (ROC) analysis. Spearman correlation analyses were conducted to investigate the relationship between brain synaptic density and disease severity RESULTS: Patients with MSA displayed extensive reductions in synaptic density throughout the brain, notably affecting both primary VOIs (the cerebellum and putamen) and secondary VOIs including the medulla oblongata, ventral tegmental area, and pons. Notably, patients with MSA-C exhibited a remarkable decrease in cerebellar synaptic density, whereas patients with MSA-P demonstrated significant synaptic loss within the posterior putamen. Compared with patients with PD, the patients with MSA show a more pronounced reduction in synaptic density in infratentorial brain regions. VOI-based diagnosis significantly outperformed visual analysis in diagnosing and differentiating MSA and its subtypes. Synaptic density in primary and multiple secondary VOIs correlated significantly with motor scales in patients with MSA.

INTERPRETATION

Our study identified widespread synaptic density reductions in MSA, particularly in the basal ganglia and infratentorial region, suggesting [18F]SynVesT-1 PET as a potential biomarker for diagnosing and evaluating the disease, and guiding synaptic restoration trials. ANN NEUROL 2025;97:879-893.

The potential of brain organoids in addressing the heterogeneity of synucleinopathies

Synucleinopathies are a group of diseases characterized by neuronal and glial accumulation of α-synuclein (aSyn) linked with different clinical presentations, including Parkinson's disease (PD), Parkinson's disease with dementia (PDD), Dementia with Lewy Bodies (DLB) and Multiple system atrophy (MSA). Interestingly, the structure of the aSyn aggregates can vary across different synucleinopathies. Currently, it is unclear how the aSyn protein can aggregate into diverse structures and affect distinct cell types and various brain regions, leading to different clinical symptoms. Recent advances in induced pluripotent stem cells (iPSCs)-based brain organoids (BOs) technology provide an unprecedented opportunity to define the etiology of synucleinopathies in human brain cells within their three-dimensional (3D) context. In this review, we will summarize current advances in investigating the mechanisms of synucleinopathies using BOs and discuss the scope of this platform to define mechanisms underlining the selective vulnerability of cell types and brain regions in synucleinopathies.

Association between adiponectin and lipids in Parkinson's disease

OBJECTIVES

There is increasing evidence linking Parkinson's disease (PD) to lipids, such as the presence of lipids in the core of Lewy bodies in PD brains or high-molecular-weight adiponectin (APN) in phosphorylated α-synuclein-positive Lewy bodies. This study aimed to verify whether APN levels are associated with neurodegenerative diseases. The association between APN and body weight was also investigated.

MATERIALS AND METHODS

The following parameters were measured using venous blood sampling: HDL-C, LDL-C, glucose, and lipids, including APN.

RESULTS

PD patients receiving dopaminergic treatments had significant higher APN than that of de-novo PD, progressive supranuclear palsy (PSP) or multiple system atrophy- parkinsonian type (MSA-P). Multivariate analysis using ANCOVA revealed a significant difference in APN levels between treated PD patients and de-novo PD patients (adjusted mean difference of -4.273 μg/ml, p = 0.037]), or PSP patients (adjusted mean difference of -4.756 μg/ml, p = 0.034]). BMIs were mildly higher in de-novo PD patients compared to treated PD patients (adjusted mean difference of 1.686, p = 0.074]). After adjustment, APN levels were positively correlated with HDL-cholesterol (HDL-C) in patients with PD (regression coefficient=0.479, P < 0.001), but not total cholesterol, or LDL-C. This correlation was not evident in patients with MSA-P, or PSP.

CONCLUSIONS

APN likely plays a role in the composition of lipid rafts, particularly in patients with treated PD. The correlation between APN and HDL-C may be a marker that differentiates PD from MSA-P, or PSP.

Potential Separation of Multiple System Atrophy and Parkinson's Disease by Susceptibility-derived Components

BACKGROUND

Substantial evidence emphasizes the dysregulation of iron homeostasis, demyelination and oxidative stress in the neurodegenerative process of multiple system atrophy (MSA) and Parkinson's disease (PD), although its clinical implications remain unclear. Recent MRI post-processing techniques leveraging magnetic susceptibility properties provide a noninvasive means to characterize iron, myelin content and oxygen metabolism alterations. This study aims to investigate subcortical alterations of susceptibility-derived metrics in these two synucleinopathies.

METHODS

A cohort comprising 180 patients (122 with PD and 58 with MSA) and 77 healthy controls (HCs) underwent clinical evaluation and multi-echo gradient echo MRI scans. Susceptibility source separation, susceptibility-based oxygen extraction fraction (OEF) mapping and semiautomatic subcortical nuclei segmentation were utilized to derive parametric values of deep gray matter in all subjects.

RESULTS

MSA patients showed markedly elevated paramagnetic susceptibility values in the putamen, globus pallidus (GP) and thalamus; increased diamagnetic susceptibility values in the putamen and dentate nucleus; and reduced OEF values across all nuclei compared with PD patients and HCs. Whereas PD exhibited increased positive susceptibility values in the substantia nigra and enhancing negative values in the GP, similar to MSA. Notably, age-related reductions in OEF were evident in HCs, which was altered by the MSA pathology. Paramagnetic susceptibility was correlated with disease severity. Moreover, the susceptibility-derived metrics of striatum and midbrain nuclei proved to be effective predictors to distinguish PD from MSA (AUC = 0.833).

CONCLUSION

Susceptibility-derived metrics could detect pathological involvement distinct to each disease, offering significant potential for differentiating between MSA and PD in clinical settings.

The genetic landscape of sporadic adult-onset degenerative ataxia: a multi-modal genetic study of 377 consecutive patients from the longitudinal multi-centre SPORTAX cohort

BACKGROUND

While most sporadic adult-onset neurodegenerative diseases have only a minor monogenic component, given several recently identified late adult-onset ataxia genes, the genetic burden may be substantial in sporadic adult-onset ataxias. We report systematic mapping of the genetic landscape of sporadic adult-onset ataxia in a well-characterised, multi-centre cohort, combining several multi-modal genetic screening techniques, plus longitudinal natural history data.

METHODS

Systematic clinico-genetic analysis of a prospective longitudinal multi-centre cohort of 377 consecutive patients with sporadic adult-onset ataxia (SPORTAX cohort), including clinically defined sporadic adult-onset ataxia of unknown aetiology (SAOA) (n = 229) and 'clinically probable multiple system atrophy of cerebellar type' (MSA-Ccp) (n = 148). Combined GAA-FGF14 (SCA27B) and RFC1 repeat expansion screening with next-generation sequencing (NGS) was complemented by natural history and plasma neurofilament light chain analysis in key subgroups.

FINDINGS

85 out of 377 (22.5%) patients with sporadic adult-onset ataxia carried a pathogenic or likely pathogenic variant, thereof 67/229 (29.3%) patients with SAOA and 18/148 (12.2%) patients meeting the MSA-Ccp criteria. This included: 45/377 (11.9%) patients with GAA-FGF14≥250 repeat expansions (nine with MSA-Ccp), 17/377 (4.5%) patients with RFC1 repeat expansions (three with MSA-Ccp), and 24/377 (6.4%) patients with single nucleotide variants (SNVs) identified by NGS (six with MSA-Ccp). Five patients (1.3%) were found to have two relevant genetic variants simultaneously (dual diagnosis).

INTERPRETATION

In this cohort of sporadic adult-onset ataxia, a cohort less likely to have a monogenic cause, a substantial burden of monogenic variants was identified, particularly GAA-FGF14 and RFC1 repeat expansions. This included a substantial share of patients meeting the MSA-Ccp criteria, suggesting a reduced specificity of this clinical diagnosis and potential co-occurrence of MSA-C plus a second, independent genetic condition. These findings have important implications for the genetic work-up and counselling of patients with sporadic ataxia, even when presenting with MSA-like features. With targeted treatments for genetic ataxias now on the horizon, these findings highlight their potential utility for these patients.

FUNDING

This work was supported by the Clinician Scientist programme "PRECISE.net" funded by the Else Kröner-Fresenius-Stiftung (to DM, AT, CW, OR, and MS), by the Deutsche Forschungsgemeinschaft (as part of the PROSPAX project), and by the Canadian Institutes of Health Research and the Fondation Groupe Monaco. Support was also provided by Humboldt Research Fellowship for Postdocs and the Hertie-Network of Excellence in Clinical Neuroscience and a Fellowship award from the Canadian Institutes of Health Research.

18F-FDG PET/MRI in Multiple System Atrophy-Parkinsonian Type (MSA-P)

A 64-year-old woman presented with a progressive movement disorder for 4 years, characterized by freezing of gait and left lower extremity discoordination. DaTScan performed 1 year after the presentation was abnormal and consistent with Parkinsonian syndrome. The patient went on to suffer from orthostatic symptomatology resulting in loss of consciousness. She also suffered from urinary incontinence and nocturia. The patient then underwent 18F-FDG brain PET/MRI, which demonstrated markedly decreased tracer uptake in the bilateral putamina, with accompanying putaminal atrophy, marginal T2-hyperintensity (putaminal rim sign), and central T2* hypointensity. Collectively the imaging findings and clinical presentation are compatible with multiple system atrophy, parkinsonian type (MSA-P).

Predicting Phenoconversion in Isolated RBD: Machine Learning and Explainable AI Approach

Isolated rapid eye movement (REM) sleep behavior disorder (iRBD) is recognized as a precursor to neurodegenerative diseases. This study aimed to develop predictive models for the timing and subtype of phenoconversion in iRBD. We analyzed comprehensive clinical data from 178 individuals with iRBD over a median follow-up of 3.6 years and applied machine learning models to predict when phenoconversion would occur and whether progression would present with motor- or cognition-first symptoms. During follow-up, 30 patients developed a neurodegenerative disorder, and the extreme gradient boosting survival embeddings-Kaplan neighbors (XGBSE-KN) model demonstrated the best performance for timing (concordance index: 0.823; integrated Brier score: 0.123). Age, antidepressant use, and Movement Disorder Society-Unified Parkinson's Disease Rating Scale Part III scores correlated with higher phenoconversion risk, while coffee consumption was protective. For subtype classification, the RandomForestClassifier achieved the highest performance (Matthews correlation coefficient: 0.697), indicating that higher Montreal Cognitive Assessment scores and younger age predicted motor-first progression, whereas longer total sleep time was associated with cognition-first outcomes. These findings highlight the utility of machine learning in guiding prognosis and tailored interventions for iRBD. Future research should include additional biomarkers, extend follow-up, and validate these models in external cohorts to ensure generalizability.

Clinical utility of cerebrospinal fluid Alzheimer's disease biomarkers in the diagnostic workup of complex patients with cognitive impairment

Cerebrospinal fluid (CSF) biomarkers have been widely adopted in Alzheimer's disease (AD) diagnosis. However, no studies focused on the application of CSF biomarkers in the clinical practice of complex and atypical patients with cognitive impairment in China. This study aimed to evaluate the added value of CSF AD biomarkers in cognitively impaired patients with complex conditions in a memory clinical setting. A total of 633 participants were included from the National Center for Neurological Disorders in Shanghai, China. The CSF AD biomarkers were measured with ELISA. Cutoff values were firstly identified using Youden's index. The neurologists proposed etiology diagnosis with a percentage estimate of their confidence and prescribed medication before and after CSF disclosure. Changes in etiological diagnosis, diagnostic confidence, and management plan were compared across the groups. Of the 633 patients (mean [SD] age, 61.1 [11.3] years; 295 males [46.6%]), 372 (58.8%) were diagnosed with dementia, 103 (16.3%) with mild cognitive impairment, and 158 (24.9%) with subjective cognitive decline. Using those pre-defined cutoffs, we categorized patients into 3 groups: Alzheimer's continuum (68.1%), non-AD pathologic change (11.1%), and normal AD biomarkers (20.8%). After CSF disclosure, the proposed etiology changed in 158 (25.0%) participants and the prescribed medication changed in 200 (31.6%) patients. Mean diagnostic confidence increased from 69.5-83.0% (+13.5%; P < 0.001). In conclusion, CSF AD biomarkers significantly impacted the diagnosis, diagnostic confidence, and treatment plans for Chinese patients with complex cognitive impairment. CSF AD biomarkers are a useful tool for clinicians beyond routine clinical assessment.

Decreased urinary excretion of norepinephrine and dopamine in autonomic synucleinopathies

BACKGROUND

Autonomic synucleinopathies feature autonomic failure and intracellular deposition of the protein alpha-synuclein. Three such conditions are the Lewy body diseases (LBDs) Parkinson's disease (PD) and pure autonomic failure (PAF) and the non-LBD synucleinopathy multiple system atrophy (MSA). These diseases all entail catecholaminergic abnormalities in the brain, sympathetically innervated organs, or both; however, little is known about renal catecholaminergic functions in autonomic synucleinopathies. We measured urinary excretion rates of the sympathetic neurotransmitter norepinephrine, the hormone epinephrine, the autocrine-paracrine substance dopamine, the catecholamine precursor 3,4-dihydroxyphenylalanine (DOPA), 3,4-dihydroxyphenylglycol (DHPG, the main neuronal metabolite of norepinephrine), and 3,4-dihydroxyphenylacetic acid (DOPAC, a major dopamine metabolite), in PD, PAF, and MSA groups and controls.

METHODS

Data were reviewed from all research participants who had urine collections (usually 3.5 h) at the National Institutes of Health (NIH) Clinical Center from 1995 to 2024. The control cohort had neither autonomic failure nor a movement disorder.

RESULTS

Norepinephrine excretion rates were decreased compared with controls in PD (p = 0.0001), PAF (p < 0.0001), and MSA (p < 0.0001). Dopamine excretion was also decreased in the three groups (PD: p = 0.0136, PAF: p = 0.0027, MSA: p = 0.0344). DHPG excretion was decreased in PD (p = 0.0004) and PAF (p = 0.0004) but not in MSA. DOPA and epinephrine excretion did not differ among the study groups.

CONCLUSIONS

Autonomic synucleinopathies involve decreased urinary excretion rates of norepinephrine and dopamine. Since virtually all of urinary dopamine in humans is derived from circulating DOPA, the low rates of urinary norepinephrine and dopamine excretion may reflect dysfunctions in the renal sympathetic noradrenergic system, the DOPA-dopamine autocrine-paracrine system, or both systems.

Central Involvement in Pure Autonomic Failure: Insights from Neuromelanin-Sensitive Magnetic Resonance Imaging and 18F-Fluorodopa-Positron Emission Tomography

BACKGROUND

Central synucleinopathies, including Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA), involve alpha-synuclein accumulation and dopaminergic cell loss in the substantia nigra (SN) and locus coeruleus (LC). Pure autonomic failure (PAF), a peripheral synucleinopathy, often precedes central synucleinopathies.

OBJECTIVES

To assess early brain involvement in PAF using neuromelanin-sensitive magnetic resonance imaging (NM-MRI) and fluorodopa-positron emission tomography (FDOPA-PET), and to determine whether PAF patients with a high likelihood ratio (LR) for conversion to a central synucleinopathy exhibit reduced NM-MRI contrast in the LC and SN compared with controls and low-LR patients.

METHODS

Participants with PAF (n = 23) were categorized as high-LR (n = 13) or low-LR (n = 10) for conversion to central synucleinopathy. Additional participants included PD (n = 22), DLB (n = 8), and age- and sex-matched healthy controls (n = 23). NM-MRI at 3 T was used to quantify contrast ratios in the LC and SN, while FDOPA-PET measured presynaptic dopamine synthesis. Linear regression analyses, adjusted for age and sex, were used to compare NM-MRI contrast across groups.

RESULTS

High-LR PAF patients showed reduced contrast in the LC and SN compared with controls and low-LR PAF patients, with values similar to PD and DLB. The NM-MRI contrast in the SN correlated with dopamine uptake in the striatum. Longitudinal imaging in PAF patients (n = 6) demonstrated reduced NM-MRI and PET values in individuals who developed central synucleinopathies.

CONCLUSIONS

NM-MRI and FDOPA-PET may serve as potential biomarkers for early brain involvement and predicting progression to central synucleinopathies in PAF and could help identify patients for early intervention. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

A strategic approach of the management of sleep-disordered breathing in multiple system atrophy

STUDY OBJECTIVES

Multiple system atrophy (MSA) is a rare neurodegenerative disorder characterized by autonomic dysfunction associated with a combination of cerebellar, parkinsonian, or pyramidal signs. Sleep-disordered breathing such as stridor, obstructive sleep apnea, and central sleep apnea is common in MSA and can impact survival. Several studies have evaluated treatment modalities. However, the optimal strategy often remains unclear in these patients. This review aims to provide an overview of the current evidence on treatment of sleep-disordered breathing in MSA.

METHODS

Systematic review of the current literature through combined keyword search in PubMed, Embase, the Cochrane Library, and cited references: "multiple system atrophy," "stridor," "sleep apnea syndrome," "sleep-disordered breathing," "Shy Drager syndrome."

RESULTS

Twenty-nine papers were included, with a total of 681 patients with MSA and sleep-disordered breathing. Treatment modalities are: continuous positive airway pressure, tracheostomy, tracheostomy-invasive ventilation, noninvasive positive pressure ventilation, adaptive servoventilation, vocal cord surgery, botulinum toxin injections, oral appliance therapy, cervical spinal cord stimulation, selective serotonin reuptake inhibitors.

CONCLUSIONS

Conflicting results on survival are found for continuous positive airway pressure therapy. Tracheostomy has a proven survival benefit. Most beneficial outcomes are seen with tracheostomy-invasive ventilation. Continuous positive airway pressure, other types of positive airway pressure therapy and tracheostomy can adequately control symptoms of obstructive sleep apnea. However, continuous positive airway pressure may exacerbate central sleep apnea. There was a lack of sufficient data regarding servoventilation or noninvasive positive pressure ventilation. Some patients exhibit a floppy epiglottis and require a different approach. In conclusion, due to the complex characteristics of sleep-disordered breathing in MSA, an individualized and multidisciplinary approach is mandatory.

CITATION

Laga A, Bauters F, Hertegonne K, Tomassen P, Santens P, Kastoer C. A strategic approach of the management of sleep-disordered breathing in multiple system atrophy. J Clin Sleep Med. 2025;21(4):703-711.

Differentiating patterns of neuro-circuitry abnormalities in tremor dominant parkinson's disease and multiple system atrophy: a resting-state fMRI study

This study aimed to elucidate distinctive patterns of brain functional activity in tremor-dominant Multiple System Atrophy (MSA) and Parkinson's Disease (PD) patients and develop a diagnostic model distinguishing between the two conditions based on these changes. Resting-state fMRI data from 45 MSA patients, 55 PD patients, and 48 healthy controls were analyzed using Percent Amplitude of Fluctuation (PerAF), Functional (FC) and Effective Connectivity (EC) analyses. The Support Vector Machine (SVM) was used to create the diagnostic model from the identified functional alterations. Partial correlation analyses explored the relationship between functional abnormalities and tremors. Both MSA and PD patients with tremors exhibited similar activity changes in bilateral Orbital part of the superior frontal gyrus (ORBsup), Cerebellum VIII (CRBL8), left Cerebellum IV-V (CRBL45.L), right rectus (REC), and FC based on the seeds of PUT.L, CRBL8.R, and REC.R. These changes were more pronounced in MSA patients. However, MSA patients exhibited heightened putamen activity and enhanced EC from caudate (CAU) to putamen, whereas these activity and connectivity were decreased in PD patients. The SVM model achieved strong performance, with the putamen exerting the most significant influence on classification. In summary, dysfunction within the cerebello-cortical and basal ganglia network circuits is implicated in the tremors of both MSA and PD patients. The alteration in cerebellar-cortical regions were similar, with MSA displaying more pronounced changes, contrasting changes were observed in the basal ganglia region. The putamen may serve as crucial neurobiological indicators for the precise differentiation of MSA and PD patients.

Assessment of Piezo1 Expression in Urinary Exfoliated Cells as a Diagnostic Indicator for Multiple System Atrophy

BACKGROUND

Multiple system atrophy (MSA) shares clinical features with idiopathic Parkinson' s disease (iPD) and progressive supranuclear palsy (PSP), yet reliable biomarkers for differential diagnosis remain elusive.

OBJECTIVES

This study aimed to evaluate Piezo1/2 expression in urinary exfoliated cells as a potential biomarker for MSA differentiation.

METHODS

Piezo1/2 expression levels were quantified in urinary exfoliated cells from 76 MSA patients, 103 iPD patients, 59 PSP patients, and 126 healthy controls (HCs) across three independent cohorts using multiple analytical techniques.

RESULTS

In the discovery cohort, Piezo1 expression was significantly reduced in MSA patients compared with HCs, iPD, and PSP (area under the curve: 0.9421, 0.8218, and 0.8036, respectively). These findings were validated in two independent cohorts, confirming consistently lower Piezo1 levels in MSA patients and their utility in distinguishing MSA from other groups.

CONCLUSION

Reduced Piezo1 levels in urinary exfoliated cells show strong potential as a non-invasive biomarker for diagnosing MSA. © 2025 International Parkinson and Movement Disorder Society.

Pathomechanisms of neuropsychiatric disturbances in atypical parkinsonian disorders: a current view

Multiple system atrophy (MSA), corticobasal degeneration (CBD) and progressive supranuclear palsy (PSP) are the most common atypical parkinsonisms. These adult-onset and lethal neurodegenerative disorders of unknown etiology are clinically characterized by varying combinations of autonomic, levodopa-poorly responsive parkinsonsm, motor, non-motor, cerebellar syndromes, behavioral, cognitive and other neuropsychiatric disorders. Although their pathological hallmarks are different-MSA α-synucleinopathy, CBD and PSP 4-repeat (4R) tauopathies-their neuropsychiatric disturbances include anxiety, depression, agitations, attention-executive dysfunctions, less often compulsive and REM sleep behavior disorders (RBD), which may contribute to disease progression and reduced quality of life (QoL) of patients and caregivers. The present paper reviews the prevalence and type of neuropsychiatric profile in these atypical parkinsonian syndromes, their neuroimaging, and pathogenic backgrounds based on extensive literature research. MSA patients show anxiety, apathy (depression), initial RBD, attentional and executive dysfunction; PSP patients present with apathy, depression, disinhibition, and to a lesser extent, anxiety and agitation; CBD patients are featured by executive and visuospatial dysfunctions, irritability, alien limb phenomena, sleep and language disorders. Neuropsychiatric disorders in these syndromes are often similar, due to disruption of prefronto-subcortical (limbic) and striato-thalamo-cortical circuitries or default mode and attention network disorder. This supports the concept that they are brain network disorders due to complex pathogenic mechanisms related to the basic proteinopathies that are still poorly understood. Psychotic symptoms, hallucinations and delusions are rare. Neuropsychiatric changes in these disorders are often premature and anticipate motor dysfunctions; their assessment and further elucidation of their pathogenesis are warranted as a basis for early diagnosis and adequate treatment of these debilitating comorbidities.

Investigation of the significance of quantitative MRI parameters in differentiating PSP from MSA patients

OBJECTIVE

To investigate the utility of quantitative MRI parkinsonism indices in discriminating between progressive supranuclear palsy (PSP) and multiple system atrophy (MSA) patients.

METHODS

In our study including PSP and MSA patients, we calculated the radiological measures including superior cerebellar peduncle width, middle cerebellar peduncle width, third ventricle width, 3rdV/bifrontal width, pons/mesencephalon (P/M) ratio, P/M ratio 2.0, magnetic resonance parkinsonism index (MRPI), and MRPI 2.0 values. We also constituted a PMS scale to increase the discrimination power.

RESULTS

Comparisons between PSP and MSA patients revealed significant differences in the mesencephalon area, third ventricle width, 3rdV/bifrontal width, P/M ratio, P/M ratio 2.0, MRPI, and MRPI 2.0 values (p < 0.01 for all). The AUC values were acceptable for the third ventricle width, the 3rdV/bifrontal width ratio, the P/M ratio, the P/M 2 ratio, the MRPI and the MRPI-2. In distinguishing PSP, 0 points on the PMS scale had a negative predictive value (NPV) of 91%, whereas 3 points had a positive predictive value (PPV) of 85.7%.

CONCLUSION

None of the MRI parameters reached a good diagnostic AUC in distinguishing PSP from MSA. However, the PMS scale we propose in this study may provide high PPVs and NPVs for differential diagnosis during desk-based evaluation.

Automated Imaging Differentiation for Parkinsonism

Importance

Magnetic resonance imaging (MRI) paired with appropriate disease-specific machine learning holds promise for the clinical differentiation of Parkinson disease (PD), multiple system atrophy (MSA) parkinsonian variant, and progressive supranuclear palsy (PSP). A prospective study is needed to test whether the approach meets primary end points to be considered in a diagnostic workup.

Objective

To assess the discriminative performance of Automated Imaging Differentiation for Parkinsonism (AIDP) using 3-T diffusion MRI and support vector machine (SVM) learning.

Design, Setting, and Participants

This was a prospective, multicenter cohort study conducted from July 2021 to January 2024 across 21 Parkinson Study Group sites (US/Canada). Included were patients with PD, MSA, and PSP with established criteria and unanimous agreement in the clinical diagnosis among 3 independent, blinded neurologists who specialize in movement disorders. Patients were assigned to a training set or an independent testing set.

Exposure

MRI.

Main Outcomes and Measures

Area under the receiver operating characteristic curve (AUROC) in the testing set for primary model end points of PD vs atypical parkinsonism, MSA vs PSP, PD vs MSA, and PD vs PSP. AIDP was also paired with antemortem MRI to test against postmortem neuropathology in a subset of autopsy cases.

Results

A total of 316 patients were screened and 249 patients (mean [SD] age, 67.8 [7.7] years; 155 male [62.2%]) met inclusion criteria. Of these patients, 99 had PD, 53 had MSA, and 97 had PSP. A retrospective cohort of 396 patients (mean [SD] age, 65.8 [8.9] years; 234 male [59.1%]) was also included. Of these patients, 211 had PD, 98 had MSA, and 87 had PSP. Patients were assigned to the training set (78%; 104 prospective, 396 retrospective) or independent testing set, which included 145 (22%; 60 PD, 27 MSA, 58 PSP) prospective patients (mean age, 67.4 [SD 7.7] years; 95 male [65.5%]). The model was robust in differentiating PD vs atypical parkinsonism (AUROC, 0.96; 95% CI, 0.93-0.99; positive predictive value [PPV], 0.91; negative predictive value [NPV], 0.83), MSA vs PSP (AUROC, 0.98; 95% CI, 0.96-1.00; PPV, 0.98; NPV, 0.81), PD vs MSA (AUROC, 0.98; 95% CI, 0.96-1.00; PPV, 0.97; NPV, 0.97), and PD vs PSP (AUROC, 0.98; 95% CI, 0.96-1.00; PPV, 0.92; NPV, 0.98). AIDP predictions were confirmed neuropathologically in 46 of 49 brains (93.9%).

Conclusions and Relevance

This prospective multicenter cohort study of AIDP met its primary end points. Results suggest using AIDP in the diagnostic workup for common parkinsonian syndromes.

Differential diagnosis of multiple system atrophy with predominant parkinsonism and Parkinson's disease using neural networks (part II)

Neural networks (NNs) possess the capability to learn complex data relationships, recognize inherent patterns by emulating human brain functions, and generate predictions based on novel data. We conducted deep learning utilizing an NN to differentiate between Parkinson's disease (PD) and the parkinsonian variant (MSA-P) of multiple system atrophy (MSA). The distinction between PD and MSA-P in the early stages presents significant challenges. Considering the recently reported heterogeneity and random distribution of lesions in MSA, we performed an analysis employing an NN with voxel-based morphometry data from the entire brain as input variables. The NN's accuracy in distinguishing MSA-P from PD demonstrates sufficient practicality for clinical application.

Prediction of phenoconversion into alpha-synucleinopathy in patients with isolated REM sleep behavior disorder using event-related potentials during visuospatial attention tasks

STUDY OBJECTIVES

Isolated rapid eye movement sleep behavior disorder (iRBD) is recognized as a prodromal stage of alpha-synucleinopathies. Predicting phenoconversion in iRBD patients remains a key challenge. We aimed to investigate whether event-related potentials (ERPs) recorded during visuospatial attention tasks can serve as predictors of phenoconversion in iRBD patients.

METHODS

We conducted a longitudinal study with 126 iRBD patients (aged 67.1 ± 6.4, 77 males) and 41 healthy controls (aged 66.1 ± 6.9, 29 males). Among the patients, those who further developed synucleinopathies during the follow-up period (average 6.3 years) were classified as converters (iRBD-CV), while the others were non-converters (iRBD-NC). Posner's visuospatial cueing task was performed at baseline. The N2 and P3 components were acquired for both the cue and target (valid and invalid) stimuli. Based on group comparisons, Kaplan-Meier survival analysis was performed.

RESULTS

Twenty-nine patients converted to alpha-synucleinopathies (aged 69.4 ± 7.1, 14 males). iRBD patients exhibited overall reductions in N2 components for cue, valid, and invalid stimuli compared to HC (p = 0.012, 0.047, and 0.001, respectively). iRBD-CV patients displayed a significant increase in cue-elicited P3 (p < 0.001) and a decreasing trend in cue-elicited N2 (p = 0.079) compared to iRBD-NC. These ERP alterations were strongly associated with faster rate of phenoconversion (p < 0.001 for both components).

CONCLUSION

Our findings suggest that altered cue-elicited ERPs could serve as early biomarkers for predicting phenoconversion in iRBD patients, likely reflecting attention-related neurodegeneration pathways. These biomarkers potentially enable the detection of preclinical phenotypes in alpha-synucleinopathies, facilitating timely intervention.

Characteristics of cerebral glucose metabolism in patients with cognitive impairment in multiple system atrophy

Objective

We aimed to conduct 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) to investigate the metabolic changes in brain regions associated with cognitive decline in patients with multiple system atrophy (MSA) and to assess the diagnostic efficacy of 18F-FDG PET imaging for evaluating the cognitive status of MSA patients.

Methods

This study included 44 MSA patients (MSA group) and 30 healthy controls (HC group) who underwent brain 18F-FDG PET imaging. All patients were subjected to the Mini-Mental State Examination and categorized into the MSA with normal cognition (MSA-NC) and MSA with cognitive impairment (MSA-CI) groups. Statistical parametric mapping (version 12) was used to analyze PET images and compare the differences in brain metabolism between the MSA and HC groups. The PET images of MSA-CI and MSA-NC patients were compared to analyze the metabolic characteristics, and the regional cerebral metabolic rate of glucose (rCMRglc) was calculated for different brain regions. Receiver operating characteristic (ROC) curves were used to analyze the ability of the rCMRglc of different brain regions to assess the cognitive status of MSA patients.

Results

Compared with the HC group, the MSA group showed diffuse reductions in glucose metabolism in the cerebellar regions, decreased metabolism in specific areas of the left inferior parietal lobule, right putamen, and left middle temporal gyrus, and increased metabolism in the left postcentral gyrus, right postcentral gyrus, left precuneus. Compared with the MSA-NC group, the MSA-CI group exhibited decreased metabolism in the right superior frontal gyrus and right superior parietal lobule. The rCMRglc value of the right superior frontal gyrus (Montreal Neurological Institute coordinates: 18, -6, 70) showed better diagnostic efficacy for identifying MSA-CI, with an area under the ROC curve of 0.829 (95%CI = 0.696-0.963), sensitivity of 84.6% (95%CI = 66.5-93.9%), and specificity of 83.3% (95%CI = 60.8-94.2%).

Conclusion

Compared with MSA-NC patients, the MSA-CI patients show decreased metabolism in the right superior frontal gyrus and right superior parietal lobule. The rCMRglc value of the right superior frontal gyrus may be a potential molecular imaging biomarker for diagnosing MSA-CI.

Comparison of inflammatory biomarker levels in neurodegenerative proteinopathies: a case-control study

While diagnostic criteria have been established and validated for most neurodegenerative diseases, the considerable overlap between individual nosological entities remains a significant diagnostic challenge. Increasing evidence suggests that neurodegeneration is often initiated by inflammation within the central nervous system. The identification of inflammation could serve as a first signal of the pathophysiological process. As such, validated biological markers ("biomarkers") of neuroinflammation are critically important. This study aimed to assess the presence and levels of inflammatory biomarkers in three neurodegenerative diseases: Lewy body diseases (LBD), multiple system atrophy (MSA), and 4-repeat tauopathies (4RT). A total of 83 LBD, 24 MSA, and 31 4RT patients were included, with 83 control subjects for comparison. Six immune-related proteins were analysed in cerebrospinal fluid (CSF) and blood serum (serum): C3 complement, C4 complement, haptoglobin, transferrin, orosomucoid, and β2 microglobulin (β2M). ANCOVA statistical analysis revealed significantly lower levels of several inflammatory biomarkers in LBD (CSF: transferrin, C3 complement, orosomucoid; Serum: orosomucoid, β2M) and MSA (CSF: transferrin, C3 complement, C4 complement, orosomucoid) compared to controls. Significant differences were also observed between the synucleinopathy patient groups (LBD and MSA) and 4RT in serum levels of C3 complement. Additionally, the CSF/serum quotients for transferrin (LBD and MSA) and C3 complement (LBD) were significantly lower in disease relative to controls. These findings suggest that inflammatory processes may play a role in the pathophysiology of neurodegenerative proteinopathies, warranting further research to confirm these associations. The identification of potential fluid biomarkers would then represent a promising step forward in the field.

Cognitive impairment in Parkinson's disease and other parkinsonian syndromes

In this narrative review, we address mild cognitive impairment, a frequent complication of Parkinson's disease (PD) and atypical parkinsonian disorders (APDs). Recent diagnostic criteria have blurred the lines between PD and dementia with Lewy bodies (DLB), particularly in the cognitive domain. Additionally, atypical parkinsonian syndromes like progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD) often present with significant cognitive decline. Even multiple system atrophy (MSA) can be associated with cognitive impairment in some cases. Several biomarkers, including imaging techniques, such brain magnetic resonance imaging (MRI) and fluorodeoxyglucose positron emission tomography (FDG-PET), as well as pathological proteins either of the cerebrospinal fluid (CSF), such as Tau, amyloid beta, and synuclein, or of the serum, such as neurofilament light chain (Nfl) are more and more often utilized in the early differential diagnosis of APDs. The complex interplay between these conditions and the evolving understanding of their underlying pathologies highlight the need for further research to refine diagnostic criteria, possibly incorporate the new findings from the biomarker's field into the diagnostic criteria and develop targeted therapeutic strategies.

Positron emission tomography molecular imaging for pathological visualization in multiple system atrophy

Multiple system atrophy (MSA) is a complex, heterogeneous neurodegenerative disorder characterized by a multifaceted pathogenesis. Its key pathological hallmark is the abnormal aggregation of α-synuclein, which triggers neuroinflammation, disrupts both dopaminergic and non-dopaminergic systems, and results in metabolic abnormalities in the brain. Positron emission tomography (PET) is a non-invasive technique that enables the visualization, characterization, and quantification of these pathological processes from diverse perspectives using radiolabeled agents. PET imaging of molecular events provides valuable insights into the underlying pathomechanisms of MSA and holds significant promise for the development of imaging biomarkers, which could greatly improve disease assessment and management. In this review, we focused on the pathological mechanisms of MSA, summarized relevant targets and radiopharmaceuticals, and discussed the clinical applications and future perspectives of PET molecular imaging in MSA.

Three hertz orthostatic tremor as "red flag sign" candidate for multiple system atrophy

AIM

This study investigates the potential of 3-Hz orthostatic tremor (OT) as a diagnostic red-flag sign for differentiating multiple system atrophy (MSA) from Parkinson's disease (PD).

PATIENTS AND METHODS

A total of 615 PD patients and 234 MSA patients (120 MSA-P and 114 MSA-C) participated. OT at ~ 3 Hz and other frequencies was identified through rhythmic postural sway on the stabilogram map and confirmed by fast Fourier transform (FFT) analysis. Extensive assessment of OT occurrence, preferential stance conditions, sway direction, frequency spectrum, and intensity was performed and compared between the two diseases.

RESULTS

Significant differences in OT features were observed. In PD, 104 patients (16.9%) exhibited tremors, mainly on a firm platform (79.8%), and preferentially in the medial-lateral direction (59.6%). About 40% of PD-related OT showed double peaks in the FFT map, with a frequency spectrum from 3.3 to 12.4 Hz. MSA tremors were observed in 133 patients (56.8%, including 46 MSA-P and 87 MSA-C patients), occurring after proprioceptive sensory input deprivation (94.7%). OT in MSA occurred exclusively in the anterior-posterior direction (100%), with no sub- or ultra-harmonics in the FFT map. Binominal logistic regression analyses demonstrated that frequency and stance conditions independently contributed to differentiating PD- and MSA-related OT. The 3-Hz tremor exhibited a sensitivity of 0.568, perfect specificity (1), an approximate negative predictive value of 0.8592, and a positive predictive value of 1 for MSA identification.

CONCLUSIONS

This study establishes the 3-Hz orthostatic tremor as a promising red flag sign for MSA identification.

Differences Between Patients With Multiple System Atrophy With Predominant Parkinsonism and Parkinson's Disease Based on fNIRS and Gait Analysis

OBJECTIVE

To investigate the differences in gait parameters and cortical activity during a single-task walking (STW) and cognitive dual-task walking (DTW) between multiple system atrophy with predominant parkinsonism (MSA-P) and Parkinson's disease (PD).

METHODS

24 MSA-P patients, 20 PD patients, and 22 healthy controls (HCs) were enrolled. Gait parameters were collected using a portable inertial measurement unit system, and the relative change of oxyhemoglobin (ΔHbO2) in the bilateral frontal and sensorimotor cortex was obtained by functional near-infrared spectroscopy during walking with and without cognitive tasks.

RESULTS

MSA-P patients had increased step length variability and higher ΔHbO2 in the right dorsolateral prefrontal cortex (DLPFC), relative to PD patients and HCs during the DTW condition. Meanwhile, MSA-P patients exhibited higher step length variability and ΔHbO2 in the right DLPFC during DTW compared to STW. Furthermore, mild negative correlations were found between the ΔHbO2 in the right DLPFC and step length, while there was a mild positive correlation between ΔHbO2 and step length variability during the DTW condition. Notably, receiver operating characteristic (ROC) curve analysis uncovered that the areas under the curve (AUCs) of the ΔHbO2 of the right DLPFC and step length variability during DTW were 0.798 (95% confidence interval [CI]: 0.651-0.945, sensitivity = 0.650, specificity = 0.958) and 0.721 (95% CI: 0.570-0.871, sensitivity = 0.625, specificity = 0.800), respectively.

CONCLUSION

MSA-P patients demonstrate more severe gait disturbance and increased DLPFC activity compared with PD patients and HCs. Gait parameters and cortical activity could be a potential features discerning MSA-P patients and PD patients.

Saccade, pupil, and blink abnormalities in prodromal and manifest alpha-synucleinopathies

BackgroundSaccade, pupil, and blink control are impaired in patients with α-synucleinopathies (αSYN): Parkinson's disease (PD) and multiple system atrophy (MSA). Isolated REM (rapid eye movement) Sleep Behavior Disorder (iRBD) is a prodromal stage of PD and MSA and a prime candidate for investigating early oculo-pupillo-motor abnormalities that may precede or predict conversion to clinically manifest αSYN.ObjectiveDetermine whether saccade, pupil, and blink responses in iRBD are normal or similar to those identified in PD and MSA.MethodsVideo-based eye-tracking was conducted with 68 patients with iRBD, 49 with PD, 17 with MSA, and 95 healthy controls (CTRL) performing an interleaved pro-/anti-saccade task that probed sensory, motor, and cognitive processes involved in eye movement control.ResultsHorizontal saccade and blink behavior was intact in iRBD, but abnormal in PD and MSA. iRBD patients, however, demonstrated reduced pupil dilation size, which closely resembled the changes found in PD and MSA. In the iRBD group, the extent of these pupillary changes appeared to correlate with the degree of hyposmia and reduction in dopamine transporter imaging signal.ConclusionsPupil abnormalities were present in iRBD, but blink and horizontal saccade responses were intact. Future longitudinal studies are required to determine which prodromal pupil abnormalities predict conversion from iRBD to PD or MSA and to identify the time window, in relation to conversion, when horizontal saccade responses become abnormal.

Clinical Correlates of Efficacy of Pyridostigmine in the Treatment of Orthostatic Hypotension

BACKGROUND

The cholinesterase inhibitor pyridostigmine is used to treat orthostatic hypotension by facilitating cholinergic neurotransmission in autonomic ganglia, thereby harnessing residual sympathetic tone to increase blood pressure (BP) preferentially in the upright posture. We hypothesized that less severe autonomic impairment was associated with greater pressor responses to pyridostigmine.

METHODS

To identify predictors of pressor response, linear regression analyses between the effect of pyridostigmine on upright BP and markers of autonomic impairment were retrospectively conducted on 38 patients who had a medication trial with pyridostigmine (60 mg single dose).

RESULTS

Pyridostigmine increased upright BP by 4±2/3±2 mm Hg but with a wide range of responses (-20/-15 to 29/27 mm Hg; interquartile range, -6/-4 to 11/8 mm Hg). No differences were found between multiple system atrophy (n=14) and patients with pure autonomic failure (n=24). The upright BP response to pyridostigmine was negatively correlated with supine BP and with the pressure recovery time of the Valsalva maneuver, an index of severity of autonomic impairment. In patients with multiple system atrophy, the systolic blood pressure pressor response to pyridostigmine was also positively correlated with the increase in upright heart rate divided by the fall in systolic blood pressure (∆ heart rate/∆ systolic blood pressure) and with upright plasma norepinephrine, both surrogates of residual autonomic function.

CONCLUSIONS

Patients with less severe autonomic impairment are more likely to have a positive pressor response to pyridostigmine. Importantly, in this cohort of patients with severe autonomic failure, pyridostigmine was not effective in those with supine hypertension who would benefit the most from the preferential pressor effect of the drug on upright BP.

REGISTRATION

URL: http://www.clinicaltrials.gov; Unique identifier: NCT00223691.

Frequency of FGF14 intronic GAA repeat expansion in patients with multiple system atrophy and undiagnosed ataxia in the Japanese population

Multiple system atrophy (MSA) is a neurodegenerative disorder characterized by autonomic nervous system dysfunction and cerebellar ataxia or parkinsonism. Recently, expanded GAA repeats (≥250 repeat units) in intron 1 of FGF14 have been shown to be responsible for spinocerebellar ataxia type 27B (SCA27B), a late-onset ataxia with an autosomal dominant inheritance. Patients with SCA27B may also exhibit autonomic nervous system dysfunction, potentially overlapping with the clinical presentations of MSA patients. In this study, to explore the possible involvement of expanded GAA repeats in MSA, we investigated the frequencies of expanded GAA repeats in FGF14 in 548 patients with MSA, 476 patients with undiagnosed ataxia, and 455 healthy individuals. To fully characterize the structures of the expanded GAA repeats, long-range PCR products suggesting the expansion of GAA repeats were further analyzed using a long-read sequencer. Of the 548 Japanese MSA patients, we identified one MSA patient (0.2%) carrying an expanded repeat with (GAA)≥250. Among the 476 individuals with undiagnosed ataxia, (GAA)≥250 was observed in six (1.3%); this frequency was higher than that in healthy individuals (0.2%). The clinical characteristics of the MSA patient with (GAA)≥250 were consistent with those of MSA, but not with SCA27B. Further research is warranted to explore the possibility of the potential association of expanded GAA repeats in FGF14 with MSA.

Differentiating idiopathic Parkinson's disease from multiple system atrophy-P using brain MRI-based radiomics: a multicenter study

Background

Differentiating idiopathic Parkinson's disease (IPD) from multiple system atrophy-parkinsonian type (MSA-P) is essential for optimizing patient care and prognosis, given the differences in disease progression and treatment response.

Objectives

This study aimed to develop and evaluate a radiomics-based model using magnetic resonance imaging (MRI)-derived features to distinguish IPD from MSA-P.

Design

A multicenter retrospective study.

Methods

A multicenter retrospective study was conducted with 287 patients (186 IPD and 101 MSA-P) who underwent brain MRI. Radiomic features were extracted from T1-weighted imaging and T2-weighted imaging sequences, and various machine learning classifiers were applied, including logistic regression, support vector machine (SVM), ExtraTrees, extreme gradient boosting, and Light Gradient Boosting Machine. Model performance was assessed using area under the curve (AUC), accuracy, sensitivity, and specificity. A nomogram combining clinical and radiomic features was also evaluated.

Results

The SVM model, selected as the base for the Rad-signature, achieved the best diagnostic performance, with AUCs of 0.885 and 0.900 in the training and testing cohorts, respectively. The Rad-signature significantly outperformed clinical-only models in distinguishing IPD from MSA-P. The nomogram incorporating radiomic and clinical features yielded the highest diagnostic accuracy (AUC = 0.973 and 0.963 for training and testing cohorts, respectively) and balanced sensitivity and specificity. Decision curve analysis confirmed the nomogram's clinical utility.

Conclusion

Radiomics-based MRI analysis offers a powerful tool for distinguishing IPD from MSA-P, enhancing diagnostic accuracy, and aiding personalized treatment planning. Integrating radiomic and clinical data may improve diagnostic workflows in clinical practice.

Reduced cerebellar rhythm by climbing fiber denervation is linked to motor rhythm deficits in mice and ataxia severity in patients

Cerebellar ataxia results from various genetic and nongenetic disorders and is characterized by involuntary movements that impair precision and motor rhythm. Here, we report that climbing fiber (CF) denervation is a common pathophysiology underlying motor rhythm loss in cerebellar ataxia. By examining cerebellar pathology in patients with spinocerebellar ataxia (SCA) types 1, 2, and 6 and multiple system atrophy, we identified CF degeneration with synaptic loss as a shared pathophysiology. Optogenetic silencing of CF synaptic activity in mice induced ataxia-like motor dysfunctions and loss of motor precision. In addition, CF silencing resulted in cerebellar and motor rhythm loss, another core feature of ataxia. This rhythm loss was predominantly CF dependent and resistant to Purkinje cell-specific lesioning by diphtheria toxin. Correspondingly, two patients with inferior olive pathology, the brain site that provides CFs to Purkinje cells, presented with ataxia and cerebellar rhythm loss. Patients with genetic or nongenetic cerebellar ataxia exhibited cerebellar rhythm loss that correlated with the Scale for the Assessment and Rating of Ataxia. Chemogenetic stimulation of CFs improved cerebellar and motor rhythms as well as motor performance in the SCA type 1 mouse model of ataxia. These results suggest that CF-dependent cerebellar rhythm loss occurs across different types of cerebellar ataxia, contributing to motor imprecision and motor rhythm loss, two defining features of ataxia.

Neurofilament Light Chain in Cerebrospinal Fluid and Blood in Multiple System Atrophy: A Systematic Review and Meta-Analysis

Background/Objectives: Multiple system atrophy (MSA) presents a challenging diagnosis due to its clinical overlap with other neurodegenerative disorders, especially other α-synucleinopathies. The main purpose of this systematic review and meta-analysis was to assess neurofilament light chain (NfL) differences in the CSF and blood of patients with MSA versus the healthy control group (HC), patients with Parkinson's disease (PD) and patients with Lewy body dementia (LBD). Secondarily, the diagnostic metrics of CSF and circulating NfL in MSA versus HC, PD, LBD, progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD) were discussed. Methods: MEDLINE and EMBASE were thoroughly searched for relevant case-control studies. Standardized mean differences (SMDs) were calculated separately for CSF and blood NfL per comparison. Statistical heterogeneity was assessed based on the Q and I^2 statistics. Results: Twenty-five relevant studies were retrieved. Quantitative syntheses revealed elevated CSF and circulating NfL levels in individuals with MSA versus HC [SMD = 1.80 (95%CI = 1.66, 1.94) and SMD = 2.00 (95%CI = 1.36, 2.63), respectively] versus PD [SMD = 1.65 (95%CI = 1.26, 2.03) and SMD = 1.63 (95%CI = 0.84, 2.43), respectively] as well as versus LBD [SMD = 1.17, (95%CI = 0.71, 1.63) and SMD = 0.65 (95%CI = 0.30, 1.00), respectively]. Diagnostic accuracy was outstanding for CSF and blood NfL in MSA versus HC and PD, and it was moderate in MSA versus LBD. On the other hand, it was suboptimal in MSA vs. PSP and CBD. Conclusions: Both CSF and circulating NfL levels are elevated in MSA compared to HC, PD and LBD. To achieve optimal diagnostic properties, further work is required in the standardization of processes and the establishment of reference NfL intervals and/or thresholds.

A quantitative Lewy-fold-specific alpha-synuclein seed amplification assay as a progression marker for Parkinson's disease

Misfolded α-synuclein (αSyn) is the hallmark of α-synucleinopathies such as Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). While seed amplification assays (SAA) have demonstrated ultrasensitive detection of misfolded αSyn, they have been primarily used reliably to provide binary (positive/negative) results for diagnostic purposes. We developed an SAA with enhanced specificity for Lewy-fold α-synucleinopathies and introduced a quantifiable measure correlating with clinical severity. Cerebrospinal fluid (CSF) of 170 patients with neurodegenerative diseases and controls was analyzed. Blinded measurements demonstrated 97.8% sensitivity and 100% specificity for Lewy-fold α-synucleinopathies, correctly identifying PD and DLB while excluding MSA. In addition, we validated the strain specificity of the assay by testing brain homogenates from 30 neuropathologically confirmed cases. A novel Lewy-fold pathology (LFP) score based on positive signals in a dilution series provided a quantitative measure of αSyn seeds. The LFP score significantly correlated with motor and cognitive impairment presented by Hoehn and Yahr stage, MDS-UPDRS III, and MoCA. Longitudinal tracking in seven PD cases showed progressive LFP score increases corresponding with clinical deterioration, highlighting the assay's potential for monitoring disease progression at an individual level. Our Lewy-fold-specific SAA enhances ante-mortem diagnosis and differentiates Lewy-fold α-synucleinopathies from MSA. Unlike previous assays, the LFP score offers a quantitative assessment, showing promise as a progression marker and pharmacodynamic biomarker for αSyn-targeting therapies. This represents an important step toward developing an αSyn SAA that could help to track disease progression quantitatively, with potential applications in both clinical diagnostics and therapeutic trials.

A subgroup of multiple system atrophy with rapid decline in vital capacity

INTRODUCTION

Patients with neurodegenerative disorders resulting in progressive dysphagia often require gastrostomy. Pulmonary function tests (PFTs) are crucial in presurgical evaluation; however, reports on pulmonary function in multiple system atrophy (MSA) and progressive supranuclear palsy (PSP) are limited.

MATERIALS AND METHODS

This single-center, retrospective study analyzed the PFT records from patients with MSA and PSP admitted between January 2012 and October 2023.

RESULTS

Data from 104 PFTs in 70 patients with MSA (21 MSA-P, 49 MSA-C) and 29 PFTs in 22 patients with PSP, showed a weak correlation between the percentage of measured vital capacity to the predicted vital capacity (%VC) and disease duration (MSA: -0.34 and PSP: -0.19). The variation in %VC decline was greater in MSA than in PSP, with a rapid progression (%VC < 65 % within 5 years of disease duration) in seven patients with MSA (6 MSA-P and 1 MSA-C).

CONCLUSION

A decline in %VC with disease duration was observed in both MSA and PSP, with greater variation observed in MSA. Notably, a rapid decline in %VC was predominantly observed in patients with MSA-P during the early courses.

Decision-making trends in therapeutic interventions for multiple system atrophy: a 24-year retrospective study

BACKGROUND

Managing multiple system atrophy (MSA) is challenging. While invasive interventions for amyotrophic lateral sclerosis are well-studied, those for MSA remain less explored.

OBJECTIVES

To explore factors influencing treatment choices and trends in advanced-stage MSA.

METHODS

A retrospective cohort study analyzed 128 MSA patients at Hyogo Chuo National Hospital, Japan, from 2000 to 2024, focusing on treatment period and age at onset.

RESULTS

Tracheostomy invasive ventilation (TIV) decreased after 2014 (26.9% vs. 9.2%; P = 0.023). TIV-treated patients remained similarly young before and after 2014 (age at onset 52.7 vs. 54.5 years; P = 0.659) and tracheostomy was chosen by younger patients after 2014 (58.3 vs. 51.5 years; P < 0.001). Conversely, enteral nutrition increased in older patients (57.4 vs. 62.9 years; P = 0.011).

CONCLUSIONS

In Japanese MSA, preferences for invasive treatments shifted, with younger patients favoring TIV and tracheostomy, while older patients preferred less invasive options, emphasizing personalized care.

Pathophysiological Significance of α-Synuclein in Sympathetic Nerves: In Vivo Observations

BACKGROUND AND OBJECTIVES

Lewy body diseases (LBDs) such as Parkinson disease (PD) feature increased deposition of α-synuclein (α-syn) in cutaneous sympathetic noradrenergic nerves. The pathophysiologic significance of sympathetic intraneuronal α-syn is unclear. We reviewed data about immunoreactive α-syn, tyrosine hydroxylase (TH, a marker of catecholaminergic fibers), and the sympathetic neurotransmitter norepinephrine (NE) in skin biopsies from control participants and patients with PD, the related LBD pure autonomic failure (PAF), the non-LBD synucleinopathy multiple system atrophy (MSA), or neurologic postacute sequelae of severe acute respiratory syndrome coronavirus 2 (neuro-PASC).

METHODS

In a retrospective observational study, we reviewed data about α-syn-TH colocalization indexes and immunoreactive α-syn and TH signal intensities in arrector pili muscles, blood vessels, and sweat glands from neck skin biopsies and NE concentrations in simultaneously obtained thigh skin biopsies from participants studied at the NIH Clinical Center. LBD, MSA, and control group data were assessed by analyses of variance with the Tukey post hoc test for multiple comparisons. Similar analyses were performed for patients with PD or neuro-PASC vs control.

RESULTS

Dermal α-syn-TH colocalization indexes and α-syn signal intensities from neck skin biopsies were examined in 18 controls (mean age 58 years, 50% female) and 53 LBD (66, 34%), 15 MSA (61, 33%), and 11 neuro-PASC (52, 82%) patients. The LBD group had higher α-syn-TH colocalization indexes than the controls (mean difference = 1.495, 95% CI 1.081-1.909, p < 0.0001) and increased α-syn signal intensities in all 3 skin constituents (arrector pili: mean difference = 2.743, 95% CI 1.608-3.879, p < 0.0001; blood vessels: mean difference = 2.157, 95% CI 1.095-3.219, p < 0.0001; sweat glands: mean difference = 4.136, 95% CI 1.704-6.567, p < 0.0001). The groups did not differ in either immunoreactive TH or NE. The neuro-PASC and PD groups had elevated α-syn-TH colocalization indexes compared with the controls, also with no group differences in immunoreactive TH or NE contents.

DISCUSSION

LBDs and neuro-PASC entail increased α-syn-TH colocalization indexes in skin biopsies, without evidence of local denervation or noradrenergic deficiency. The results fail to support toxicity of intraneuronal α-syn in cutaneous sympathetic noradrenergic nerves in either LBDs or neuro-PASC. The neuro-PASC data raise the possibility of sympathetic intraneuronal α-syn deposition as part of postinfectious immune or inflammatory processes.

Orthostatic hypotension is involved in cognitive impairment in patients with multiple system atrophy: a multi-center cohort study in China

BACKGROUND

Orthostatic hypotension (OH) is a common symptom of multiple system atrophy (MSA), however, its role in cognitive impairment and the mechanism in these patients remains unclear. This study aims to assess the role of OH on cognitive impairment in MSA patients, as well as to explore the potential association of cerebral autoregulation (CA) and white matter hyperintensities (WMHs) on cognitive impairment.

METHODS

This observational study was conducted in three general hospitals in China from January 2018 to October 2023, with patients at one center followed up for 6 months after enrollment. The primary outcomes included cognitive function assessed using the Mini-Mental State Examination (MMSE) and Montreal cognitive assessment (MoCA). Secondary outcomes included the results of the Head-up tilt test, scores for CA and the extent of WMHs.

RESULTS

The 132 MSA patients included 72 men (54.54%) with a mean age of 61.16 (7.80) years. Among them, 80 patients (60.61%) had orthostatic hypotension, and 48 patients (36.36%) had cognitive impairment. OH plays an important role in cognitive impairment in MSA patients (OR = 0.328,95% CI 0.135-0.797, P = 0.014). Cognitive impairment was associated with impaired CA (OR = 0.088,95% CI 0.012-0.657, P = 0.018) and severe WMHs (OR = 0.030,95% CI 0.002-0.423, P = 0.009), particularly in the presence of OH.

CONCLUSION

OH is associated with cognitive impairment in MSA patients, and cognitive decline is linked to impaired CA and increased WMHs. Future studies are needed to explore the mechanisms underlying cognitive impairment in MSA patients.

α-Synuclein orchestrates Th17 responses as antigen and adjuvant in Parkinson's disease

Recently, the role of T cells in the pathology of α-synuclein (αS)-mediated neurodegenerative disorders called synucleinopathies, including Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy, has attracted increasing attention. Although the existence of αS-specific T cells and the immunogenicity of the post-translationally modified αS fragment have been reported in PD and DLB, the key cellular subset associated with disease progression and its induction mechanism remain largely unknown.Peripheral blood mononuclear cells (PBMCs) from synucleinopathy patients and healthy controls were cultured in the presence of the αS peptide pools. Cytokine analysis using culture supernatants revealed that C-terminal αS peptides with a phosphorylated serine 129 residue (pS129), a feature of pathological αS aggregates, promoted the production of IL-17A, IL-17F, IL-22, IFN-γ and IL-13 in PD patients compared with that in controls. In pS129 peptide-reactive PD cases, Ki67 expression was increased in CD4 T cells but not in CD8 T cells, and intracellular cytokine staining assay revealed the existence of pS129 peptide-specific Th1 and Th17 cells. The pS129 peptide-specific Th17 responses, but not Th1 responses, demonstrated a positive correlation with the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part III scores. A similar correlation was observed for IL-17A levels in the culture supernatant of PBMCs from PD patients with disease duration < 10 years. Interestingly, enhanced Th17 responses to pS129 peptides were uniquely found in PD patients among the synucleinopathies, suggesting that Th17 responses are amplified by certain mechanisms in PD patients. To investigate such mechanisms, we analyzed Th17-inducible capacity of αS-exposed dendritic cells (DCs). In vitro stimulation with αS aggregates generated Th17-inducible DCs with IL-6 and IL-23 production through the signaling of TLR4 and spliced X-box binding protein-1 (XBP1s). In fact, the levels of IL-6 and IL-23 in plasma, and the XBP1s ratio in type 2 conventional DCs were increased in PD patients compared with those in controls.Here, we propose the importance of αS-specific Th17 responses in the progression of PD and the underlying mechanisms inducing Th17 responses. These findings may provide novel therapeutic strategies to prevent disease development through the suppression of TLR4-XBP1s-IL-23 signaling in DCs.

Locus coeruleus neuromelanin, cognitive dysfunction, and brain metabolism in multiple system atrophy

BACKGROUND

Cognitive dysfunction is increasingly recognized in multiple system atrophy (MSA). Locus coeruleus (LC) integrity is associated with cognitive performance both in healthy controls (HC) and neurodegenerative conditions such as Parkinson's disease (PD). Furthermore, cortical glucose hypometabolism is associated with impaired cognitive performance in MSA. However, knowledge about LC sub-regional degeneration and its association with cognitive dysfunction and cortical glucose metabolism is lacking.

OBJECTIVE

To investigate LC sub-regional involvement and its association with cognitive impairment and brain metabolism in MSA.

METHODS

Eleven MSA, eighteen PD, and eighteen HC participants were included in the study. Neuromelanin-sensitive MRI was used to determine rostral, middle and caudal LC neuromelanin signals. Brain glucose metabolism was investigated with [18F]Fluorodeoxyglucose PET (FDG-PET). The Montreal Cognitive Assessment (MoCA) was used as a measure of global cognition.

RESULTS

Middle LC neuromelanin signal was significantly reduced in MSA [t(43) = 3.70, corrected-p = 0.004] and PD [t(43) = 2.63, corrected-p = 0.041] compared to HC, while caudal LC was only reduced in MSA [t(43) = 2.82, corrected-p = 0.030]. In MSA, decreased rostral LC neuromelanin was associated with lower MoCA scores (ρ = 0.760, p = 0.006) which, in turn, were associated with lower frontal cortex glucose metabolism. An association between rostral LC neuromelanin signal and frontal cortex glucose metabolism was found in exploratory analyses.

CONCLUSION

Loss of LC neuromelanin signal was found in MSA, the middle and caudal parts being targeted. Rostral LC neuromelanin signal loss was associated with both frontal cortex hypometabolism and lower MoCA scores. This pathophysiological link should be further investigated as the noradrenergic system transmission is amenable to pharmacological manipulation.

Dopamine transporter availability based on white matter hyperintensity during early to mid-stage Parkinson's disease and multiple system atrophy: a case control study

PURPOSE

To evaluate the association of white matter hyperintensity (WMH) with dopamine transporter (DAT) availability in patients with early to mid-stage parkinson's disease (PD) and multiple system atrophy (MSA).

METHODS

The clinical and imaging data of 55 patients were collected, including 38 PD and 17 MSA patients and the clinical features of the two groups were compared. DAT specific binding ratio (SBR) were compared between severe and non-severe WMH groups, and between PD and MSA groups. The relationships of WMH with DAT availability and basic clinical characteristics were analyzed.

RESULTS

Multiple linear regression analysis showed that age was the only significant variable showing correlation WMH. Age was the only clinical variable significantly correlated with WMH in PD patients (coefficient for periventricular white matter hyperintensity: 0.430, P = 0.007; coefficient for deep white matter hyperintensity: 0.381, P = 0.018). There was no significant correlation between WMH and SBRs and age in MSA patients. The SBR of the caudate nucleus and anterior putamen was significantly lower in the severe WMH group of patients than in the non-severe WMH group (P < 0.05). The values of the caudate nucleus, anterior putamen, and anterior putamen/posterior putamen were significantly lower in PD patients with than without severe WMH (P < 0.05), and the damage to the striatal DAT in MSA patients with severe WMH was similar to the non-severe patients (P>0.05).

CONCLUSION

Patients with PD and a high WMH score had lower DAT availability. WMH affected the availability of DAT in patients with early to mid-stage PD compared to MSA.

Cholinergic degeneration and early cognitive signs in prodromal Lewy body dementia

INTRODUCTION

Isolated REM sleep behavior disorder (iRBD) is a strong prodromal marker of Lewy body diseases (LBDs) - Parkinson's disease (PD) and dementia with Lewy bodies (DLB). Cholinergic loss is linked to cognitive decline in these conditions, but its trajectory remains unclear.

METHODS

In a cohort of 92 iRBD participants with baseline MRI, cholinergic basal forebrain (cBF) volume was measured, with longitudinal changes analyzed in 49 with follow-up scans. Cross-sectional neuropsychological associations were examined across a broader RBD-LBD continuum, including the iRBD cohort plus 65 PD and 15 DLB patients with probable RBD.

RESULTS

cBF volume declined at comparable rates in iRBD-to-PD and iRBD-to-DLB converters, but atrophy was more severe at DLB phenoconversion. cBF atrophy correlated with attention, executive, and memory deficits. In iRBD, baseline cBF z-score < -1.0 predicted dementia (hazard ratio = 9.57, p = .009).

CONCLUSION

cBF degeneration evolves from the prodromal iRBD stage of LBDs and predicts dementia, highlighting a window for cholinergic-targeted intervention.

HIGHLIGHTS

Basal forebrain links to attention, executive function, and memory in the RBD continuum. Basal forebrain atrophy progresses at similar rates in prodromal PD and prodromal DLB. At phenoconversion, basal forebrain atrophy is greater in DLB than in PD converters. Basal forebrain atrophy strongly predicts future dementia in iRBD. Executive dysfunction predicts faster basal forebrain degeneration in iRBD.

Toward a biological definition of neuronal and glial synucleinopathies

Cerebral accumulation of alpha-synuclein (αSyn) aggregates is the hallmark event in a group of neurodegenerative diseases-collectively called synucleinopathies-which include Parkinson's disease, dementia with Lewy bodies and multiple system atrophy. Currently, these are diagnosed by their clinical symptoms and definitively confirmed postmortem by the presence of αSyn deposits in the brain. Here, we summarize the drawbacks of the current clinical definition of synucleinopathies and outline the rationale for moving toward an earlier, biology-anchored definition of these disorders, with or without the presence of clinical symptoms. We underscore the utility of the αSyn seed amplification assay to detect aggregated αSyn in living patients and to differentiate between neuronal or glial αSyn pathology. We anticipate that a biological definition of synucleinopathies, if well-integrated with the current clinical classifications, will enable further understanding of the disease pathogenesis and contribute to the development of effective, disease-modifying therapies.

The Spectrum of Cognitive Impairment in Atypical Parkinsonism Syndromes: A Comprehensive Review of Current Understanding and Research

Multiple system atrophy (MSA), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD) are the most common atypical parkinsonism (AP) syndromes. They are clinically characterized by varying combinations of levodopa-poorly responsive parkinsonism, motor, cerebellar, and other signs. They are associated with a wide spectrum of non-motor symptoms, including prominent cognitive impairment such as global cognitive deficits, memory, executive, attentional, visuospatial, language, and non-verbal reasoning dysfunctions. Within the APs, their cognitive functioning is distributed along a continuum from MSA with the least impaired cognitive profile (similar to Parkinson's disease) to PSP and CBD with the greatest decline in global cognitive and executive domains. Although their pathological hallmarks are different-MSA α-synucleinopathy, CBD, and PSP 4-repeat tauopathies-cognitive dysfunctions in APs show both overlaps and dissimilarities. They are often preceding and anticipate motor dysfunctions, finally contributing to reduced quality of life of patients and caregivers. The present paper will review the current evidence of the prevalence and type of cognitive impairment in these AP syndromes, their neuroimaging, pathogenic backgrounds, and current management options based on extensive literature research. Cognitive dysfunctions in APs are due to disruption of prefronto-subcortical and striato-thalamo-cortical circuitries and multiple essential brain networks. This supports the concept that they are brain network disorders due to complex pathogenic mechanisms related to the basic proteinopathies that are still poorly understood. Therefore, the pathophysiology and pathogenesis of cognitive impairment in APs deserve further elucidation as a basis for early diagnosis and adequate treatment of these debilitating comorbidities.

The Role of the Claustrum in Parkinson's Disease and Vascular Parkinsonism: A Matter of Network?

BACKGROUND

The mechanisms underlying extrapyramidal disorders and their anatomical substrate have been extensively investigated. Recently, the role of the claustrum in Parkinson's disease and other neurodegenerative conditions has been better detailed. The main aim of this review was to summarize the supporting evidence for the role of the claustrum in degenerative and vascular parkinsonism.

METHODS

The anatomy, biology, vascular supply, and connections of the claustrum in humans were identified and described, providing the substrate for the vascular involvement of the claustrum in large- and small-vessel disease. The vascular supply of the claustrum includes up to three different sources from a single artery, the middle cerebral artery, and it is known as territory with an intermediate hemodynamic risk. The connections of the claustrum make it a sensory integrator and a relevant point in several networks, from consciousness to movement planning.

CONCLUSIONS

The claustrum is still an incompletely explained structure. However, recent description of its multiple connections indicate that it is involved in several diseases, including Parkinson's disease. The evidence underlying its potential role in vascular parkinsonism is still scarce, but it might be a field warranting future investigations.

Long-read sequencing revealed complex biallelic pentanucleotide repeat expansions in RFC1-related Parkinson's disease

Biallelic intronic pentanucleotide repeat expansions, mainly (AAGGG)exp and/or (ACAGG)exp in RFC1, are detected in cerebellar ataxia, neuropathy and vestibular areflexia syndrome, late-onset ataxia, and in a wide disease spectrum including Charcot-Marie-Tooth disease, multiple system atrophy, and Parkinson's disease (PD). However, the genotype-phenotype correlation and underlying mechanism are mostly unknown. We screened RFC1-repeat expansions in 1445 patients with parkinsonism. Comprehensive genetic and clinical, and pathological assessments were performed. We report two early-onset patients with PD carrying complex biallelic pentanucleotide repeat expansions in RFC1. Long-read sequencing revealed a novel repeat configuration of (AGGGG)exp(AAGGG)14 and a possible somatic variant of (AAGGG)exp(AATGG)exp(AAGGG)exp in the (AAGGG)exp alleles in two RFC1-related PD patients. RNA foci were detected in the (AGGGG)exp-expressed HEK293T cell line as well as (AAGGG)exp and (ACAGG)exp, supporting (AGGGG)exp as a novel pathogenic repeat motif. This work revealed complex genotypes with novel repeat configuration of (AGGGG)exp and possible somatic (AATGG)exp insertion in RFC1-related PD.

Recent Advances in the Genetics of Ataxias: An Update on Novel Autosomal Dominant Repeat Expansions

PURPOSE OF REVIEW

Autosomal dominant cerebellar ataxias, also known as spinocerebellar ataxias (SCAs), are genetically and clinically diverse neurodegenerative disorders characterized by progressive cerebellar dysfunction. Despite advances in sequencing technologies, a large proportion of patients with SCA still lack a definitive genetic diagnosis. The advent of advanced bioinformatic tools and emerging genomics technologies, such as long-read sequencing, offers an unparalleled opportunity to close the diagnostic gap for hereditary ataxias. This article reviews the recently identified repeat expansion SCAs and describes their molecular basis, epidemiology, and clinical features.

RECENT FINDINGS

Leveraging advanced bioinformatic tools and long-read sequencing, recent studies have identified novel pathogenic short tandem repeat expansions in FGF14, ZFHX3, and THAP11, associated with SCA27B, SCA4, and SCA51, respectively. SCA27B, caused by an intronic (GAA)•(TTC) repeat expansion, has emerged as one of the most common forms of adult-onset hereditary ataxias, especially in European populations. The coding GGC repeat expansion in ZFHX3 causing SCA4 was identified more than 25 years after the disorder's initial clinical description and appears to be a rare cause of ataxia outside northern Europe. SCA51, caused by a coding CAG repeat expansion, is overall rare and has been described in a small number of patients. The recent identification of three novel pathogenic repeat expansions underscores the importance of this class of genomic variation in the pathogenesis of SCAs. Progress in sequencing technologies holds promise for closing the diagnostic gap in SCAs and guiding the development of therapeutic strategies for ataxia.

An audit on the assessment and management of osteoporosis in a Parkinson's and related diseases clinic in Australia

BACKGROUND

Patients with Parkinson's disease (PD) and atypical parkinsonian syndromes are at increased risk of falls and should be actively screened and treated for osteoporosis. In 2024, the Royal Australian College of General Practitioners (RACGP) revised their practice guidelines for diagnosing and managing osteoporosis in postmenopausal women and men aged over 50 years.

OBJECTIVE

We conducted the first Australian study to audit these guidelines in patients with PD and atypical parkinsonian syndromes.

METHOD

We audited all PD, Dementia with Lewy Bodies, Progressive Supranuclear Palsy and Multiple System Atrophy cases attending our neurology service between January and March 2024 against the RACGP osteoporosis guidelines. We identified patients at risk of osteoporosis or minimal trauma fractures and assessed if they had been referred to their general practitioner (GP) for appropriate management or were already receiving appropriate osteoporosis treatment.

RESULTS

This audit evaluated 230 patients, 199 of which had PD. We identified 78 patients over the age of 50 years with risk factors that should trigger a GP bone health assessment as per the guidelines. Twenty-six of these patients were already being managed appropriately. However, only 12 of the remaining 52 'at risk' patients (23%) were directed to seek screening for osteoporosis by their GP, leaving 77% (40/52) without appropriate guidance.

CONCLUSION

Our major recommendations include following the guidelines and referring patients for a bone health screen with their GP if they have risk factors for osteoporosis. This audit highlighted that assessment of osteoporosis and fracture risk by Specialists needs to be improved.

Effect of long-term transcutaneous auricular vagus nerve stimulation in multiple system atrophy-cerebellar subtype: a case report

Background

Multiple system atrophy-cerebellar subtype (MSA-C) is a predominance of cerebellar ataxia and autonomic failure. MSA-C has a rapid progression, with average 9 years from symptom onset to death. Despite its prevalence, there is still a lack of effective treatments. In recent years, it has been established that taVNS has significant therapeutic effects on epilepsy, depression, migraine, insomnia, and other diseases. Hence, we performed taVNS treatment for one MSA-C patient to explore whether taVNS could alleviate patient's motor and non-motor symptoms.

Case presentation

A 65-year-old woman diagnosed with MSA-C received taVNS treatment for the following duration and course: once a day, 40 min a time, 20 times a month continually for 12 months. Meanwhile, she received assessments of motor and non-motor symptoms at baseline, 4-weeks and 12-months after taVNS treatment. Motor symptoms assessments was made by Scale for the Assessment and Rating of Ataxia (SARA) and Unified Multiple System Atrophy Rating Scale (UMSARS), non-motor symptoms assessment by Pittsburgh Sleep Quality Index (PSQI), Hamilton Anxiety Scale (HAMA), and Hamilton Depression Scale (HAMD). After 4-weeks and 12-months of taVNS treatment, compared to baseline assessments, SARA scores decreased from 13 to 11 and then to 10.5, UMSARS scores from 28 to 24 and then to 23, PSQI scores from 19 to 13 and then to 6, HAMA scores from 13 to 3 and then remained unchanged, and HAMD scores from 7 to 4 and then remained unchanged.

Conclusion

In the case, we found that short-term taVNS treatment can alleviate ataxia, sleep problem, anxiety and depression of the MSA-C patient. The effects can be maintained and some symptoms may be further improved after receiving long-term treatment. Our case report supports the feasibility and effectiveness of taVNS treatment in MSA-C patients.

Automated analysis of spoken language differentiates multiple system atrophy from Parkinson's disease

BACKGROUND AND OBJECTIVES

Patients with synucleinopathies such as multiple system atrophy (MSA) and Parkinson's disease (PD) frequently display speech and language abnormalities. We explore the diagnostic potential of automated linguistic analysis of natural spontaneous speech to differentiate MSA and PD.

METHODS

Spontaneous speech of 39 participants with MSA compared to 39 drug-naive PD and 39 healthy controls matched for age and sex was transcribed and linguistically annotated using automatic speech recognition and natural language processing. A quantitative analysis was performed using 6 lexical and syntactic and 2 acoustic features. Results were compared with human-controlled analysis to assess the robustness of the approach. Diagnostic accuracy was evaluated using sensitivity analysis.

RESULTS

Despite similar disease duration, linguistic abnormalities were generally more severe in MSA than in PD, leading to high diagnostic accuracy with an area under the curve of 0.81. Compared to controls, MSA showed decreased grammatical component usage, more repetitive phrases, shorter sentences, reduced sentence development, slower articulation rate, and increased duration of pauses, whereas PD had only shorter sentences, reduced sentence development, and longer pauses. Only slower articulation rate was distinctive for MSA while unchanged for PD relative to controls. The highest correlation was found between bulbar/pseudobulbar clinical score and sentence length (r = -0.49, p = 0.002). Despite the relatively high severity of dysarthria in MSA, a strong agreement between manually and automatically computed results was achieved.

DISCUSSION

Automated linguistic analysis may offer an objective, cost-effective, and widely applicable biomarker to differentiate synucleinopathies with similar clinical manifestations.

Blood biomarkers for Alzheimer's disease with the Lumipulse automated platform: Age-effect and clinical value interpretation

BACKGROUND

Advances in analytical methods have recently paved the way to Alzheimer's disease (AD) biomarkers testing in blood along with the more established CSF testing. To ensure a forthcoming application of this low-invasive diagnostic that might allow to recognize early onset of dementia, appropriate pathological cut-points need to be defined.

METHODS

In this cross-sectional study we measured blood and CSF neurofilament light chain (NFL), phosphorylated tau (pTau 181), Amyloid-β1-42 (AB 1-42) and Amyloid-β1-40 (AB 1-40) on a fully automated chemiluminescent platform (Lumipulse, Fujirebio) in 80 cognitively impaired patients and 55 cognitively unimpaired subjects. Clinical cut points were calculated with receiver-operator characteristic (ROC) curve analysis and a head-to-head comparison of blood and CSF testing was performed.

RESULTS

Blood NFL best discriminant thresholds to distinguish neurodegenerative diseases from controls varied age-dependently, being 19 and 33 pg/mL in subjects 50-65 years and > 65 years respectively. AD was best framed by AB 1-42/1-40 ratio < 0.079 and ptau181 > 1 pg/mL. Though a strong correlation for all biomarkers, only blood AB ratio was equal to CSF testing for AD diagnosis.

CONCLUSIONS

The specific context of use might be considered to define the cut-offs of blood biomarkers of neurodegenerative diseases. Future efforts towards reference materials for each AD blood biomarker will improve clinical cut-offs.

Diagnostic value of six plasma biomarkers in progressive supranuclear palsy, multiple system atrophy, and Parkinson's disease

OBJECTIVES

This study aimed to evaluate the diagnostic ability of six plasma biomarkers in progressive supranuclear palsy (PSP), multiple system atrophy (MSA), and different subtypes of Parkinson's disease (PD).

METHODS

Neurofilament light chain (NfL), phosphorylated tau-181, glial fibrillary acidic protein (GFAP), amyloid-β 42 (Aβ42), and amyloid-β 40 (Aβ40) levels were measured using the single-molecule array (Simoa) technique in a cohort of patients with PSP, MSA, different subtypes of PD, and healthy controls (HCs).

RESULTS

Plasma NfL and GFAP levels were beneficial in discriminating between the disease groups and HCs. Plasma NfL, Aβ42, and Aβ40 could distinguish atypical Parkinsonian syndrome (APS) from PD and its subtypes. GFAP could discriminate APS from tremor dominant PD but could not discriminate APS from postural instability and gait disorder dominant PD. The efficacy of differentiation improved when a combination of multiple plasma biomarkers was applied.

CONCLUSIONS

In this study, the plasma biomarkers NfL, GFAP, Aβ42, and Aβ40 exhibited high discriminatory diagnostic value in PD and APS, and could be used as clinically potential diagnostic biomarkers. Plasma biomarker combinations could improve the differential diagnostic efficacy in the comparisons of PD and APS.