Diagnosis and management of dementia with Lewy bodies: Fourth consensus report of the DLB Consortium

Hospice Use Among Medicare Beneficiaries With Parkinson Disease and Dementia With Lewy Bodies

Importance

Neurodegenerative disorders are now the most common reason that Medicare beneficiaries enroll in hospice for end-of-life care. People with all-cause dementia have high rates of suboptimal hospice use, but little is known about hospice use patterns in Lewy body disease, which includes both Parkinson disease (PD) and dementia with Lewy bodies (DLB).

Objective

To compare patient characteristics, hospice agency characteristics, and patterns of use for beneficiaries with PD and DLB vs Alzheimer disease (AD).

Design, Setting, and Participants

A retrospective cohort study including a 100% sample of national 2010-2020 calendar year Medicare data on hospice enrollees was performed. Data analysis was conducted from November 2023 to May 2024.

Exposures

A diagnosis of PD or DLB, compared with AD as the reference group.

Main Outcomes and Measures

Proportion of enrollees with short stays (<7 days), proportion with long stays (>180 days), proportion disenrolled for any reason before death, and disenrollment by type.

Results

Of 11 327 324 Medicare beneficiaries enrolled in hospice between 2010 and 2020 who met eligibility criteria (mean [SD] age, 85.2 [7.5] years; 781 763 [63.0%] female), there were 958 182 (8.4%) with a primary diagnosis of AD, 232 864 (2.1%) with PD, and 49 340 (0.4%) with DLB. People with PD were more likely to experience a long stay (odds ratio [OR], 1.15; 95% CI, 1.13-1.16) compared with AD, whereas the odds for those with DLB were not increased. However, people with either PD or DLB were less likely to be disenrolled for extended prognosis compared with AD (OR for DLB, 0.82; 95% CI, 0.79-0.85; OR for PD, 0.86; 95% CI, 0.85-0.88). People with PD were more likely to revoke hospice (OR, 1.29; 95% CI, 1.27-1.32) compared with AD.

Conclusions and Relevance

In this cohort study of Medicare beneficiaries, hospice use patterns differed by dementia subtype. Higher likelihood of hospice revocation in PD raises important questions about unmet needs and highlights the need for more research around the experience of the end of life in this growing population.

Prevalence and correlates of the head turning sign in mild cognitive impairment and dementia due to neurodegenerative, chronic cerebrovascular, and mixed etiologies

BackgroundThe head turning sign (HTS) consists in the patient turning his/her head towards the accompanying person in search for support when being asked questions. Although the HTS is known to be associated with cognitive impairment, previous investigations were biased towards Alzheimer's disease (AD) or did not differentiate between diverse dementia etiologies; moreover, little is known about the specific cognitive correlates of the HTS.ObjectiveTo assess the prevalence and clinical correlates of the HTS in patients with mild cognitive impairment (MCI) and dementia of various etiologies.MethodsThe HTS was recorded during the Mini-Mental State Examination (MMSE) in 232 MCI/dementia patients with the following etiological classification: AD (N = 121); frontotemporal lobar degeneration (FTLD; N = 24); Lewy body disease (LBD; N = 11); vascular (N = 29); mixed (N = 47).ResultsThe overall prevalence of the HTS in the whole cohort was 27.6%. Albeit being descriptively higher in dementia (29.9%) versus MCI (22.7%), as well as descriptively lower in FTLD and LBD than in remaining subgroups, no significant association was detected between the HTS and either MCI/dementia status or etiology. HTS + patients were older and more frequently females, also reporting lower MMSE scores and differing from HTS- ones on Temporal and Spatial Orientation and Constructional Praxis sub-scores. An association between the HTS and lower MMSE scores was found in patients with MCI but not in those with dementia.ConclusionsIn patients with cognitive impairment due to diverse causes, the HTS might occur regardless of MCI versus dementia status and across different etiologies. MCI patients displaying the HTS might have more severe cognitive deficits.

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.

A systematic review of biofluid phosphorylated α-synuclein in Parkinson's disease

INTRODUCTION

Parkinson's disease (PD) is a progressive neurodegenerative disease, and biomarkers are needed to enhance earlier detection and monitoring. Alpha-synuclein, phosphorylated at serine 129 (pS129-α-syn), is the predominant form of α-syn found in Lewy bodies implicating an involvement in disease pathology. This review aims to systematically evaluate the evidence for pS129-α-syn detection in human biofluid samples of PD utilizing ELISA-based protein detection methods.

METHODS

A systematic review was conducted following the Preferred Reported Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. Electronic searches were performed in PubMed, Web of Science, and Cochrane databases from inception to November 7th, 2024, to identify studies comparing pS129-α-syn in biofluids of PD patients with controls or related neurodegenerative disease. Risk of bias was assessed for each study.

RESULTS

Twenty-three publications met the inclusion criteria, with pS129-α-syn detected in cerebrospinal fluid, plasma, red blood cells, serum, and saliva exosomes. Overall, pS129-α-syn levels were elevated in patients with PD compared to controls, and in some studies, correlated with disease severity. There was no consistent pattern when comparing PD patients to those with related neurodegenerative diseases. Significant variability in pS129-α-syn levels and considerable overlap between groups may limit the utility as a biomarker.

CONCLUSION

While pS129-α-syn for PD shows some promise as a diagnostic marker for PD, its differential diagnostic utility remains limited. Further research involving larger cohorts is required. The greatest potential for pS129-α-syn may be as part of a panel with other PD-specific markers, to enhance diagnostic accuracy and prognostic value.

Novel blood-based proteomic signatures across multiple neurodegenerative diseases

INTRODUCTION

Blood-based biomarkers have the potential to support early and accurate diagnoses of neurodegenerative diseases, which are sensitive to molecular pathology and are predictive of outcome. We evaluated a novel multiplex proteomic method in people with diverse neurodegenerative diseases.

METHODS

Serum from people with Alzheimer's disease (N = 36), Lewy body dementia (N = 34), frontotemporal dementia (N = 36), and progressive supranuclear palsy (N = 36) and age-matched controls (N = 30) was analyzed with the nucleic acid linked immuno-sandwich assay (NULISA) central nervous system panel (≈ 120 analytes) and inflammation panel (250 analytes). Biomarkers were compared across groups and included as predictors of survival.

RESULTS

The NULISA panels demonstrated high sensitivity and reliability for detecting multiple biomarkers across neurodegenerative disorders. There were condition-specific proteomic biomarkers, while neurofilament light chain, corticotropin-releasing hormone, CD276, and a data-driven inflammation pattern were significant transdiagnostic outcome predictors.

DISCUSSION

The sensitive NULISA multiplex approach supports differential diagnosis and target identification, with prognostically informative dementia-related biomarkers.

HIGHLIGHTS

We tested the novel technology nucleic acid linked immuno-sandwich assay (NULISA) in people with diverse neurodegenerative diseases, which demonstrated high sensitivity and reliability for detecting multiple biomarkers in serum samples. We compared the NULISA central nervous system serum results to single molecule array (Simoa) plasma assays for phosphorylated tau (p-tau)217, p-tau231, neurofilament light chain (NfL), and glial fibrillary acidic protein, finding strong correlations. Increased levels of serum NfL were identified across all patient groups and most elevated in the frontotemporal dementia (FTD) and progressive supranuclear palsy (PSP) cohorts, while p-tau epitopes were the most significant markers in patients with Alzheimer's disease (AD) and Lewy body dementia. Patients with FTD and PSP showed upregulation of many inflammation markers, compared to controls and patients with AD. We found condition-specific proteomic biomarkers, while NfL, corticotropin-releasing hormone, CD276, and data-driven immune signatures were significant transdiagnostic predictors of clinical outcomes (survival rates).

Epigenetic and Metabolic Landscape of Dementia with Lewy Bodies

BACKGROUND

Lewy body diseases, including dementia with Lewy bodies (DLB), are characterized by α-synuclein accumulation, leading to dementia. Previous studies suggest distinct epigenetic and metabolomic profiles in DLB.

OBJECTIVE

This study aims to identify diagnostic biomarkers by analyzing the methylome and metabolome in the Brodmann area 7 of postmortem brain tissues from DLB patients and control subjects using multiomics approaches.

METHODS

Methylation analysis was performed using the Illumina EPIC array, and metabolomics profiling was conducted via 1H nuclear magnetic resonance (NMR) and direct injection/liquid chromatography coupled with mass spectrometry. Differential methylation and metabolite analysis were conducted, followed by pathway enrichment to explore biological relevance.

RESULTS

We identified 3478 significantly differentially methylated cytosines, mostly hypermethylated, enriched in CpG islands near transcription start sites. Pathway enrichment analysis showed significant pathways, primarily linked to olfactory and synaptic functions. Metabolomics profiling identified 15 significantly altered metabolites, with Phosphatidylethanolamine (PE) Biosynthesis being the most affected pathway. Key correlations between differentially methylated cytosines and metabolites, particularly in the PE Biosynthesis pathway involving PTDSS1 and PCYT2 genes, were observed.

CONCLUSIONS

Notably, sex-specific differences were found, with females exhibiting more epigenetic and metabolomic changes than males. Increased hypermethylation, linked to transcriptional silencing, and disruptions in PE biosynthesis suggest a role in synaptic dysfunction and olfactory deficits. In addition, α-aminoadipic acid was strongly associated with vascular functions, hinting at a possible overlap between vascular health and DLB. This study provides new insights into DLB mechanisms and potential therapeutic targets. © 2024 International Parkinson and Movement Disorder Society.

Current concepts and molecular pathology of neurodegenerative diseases

Neurodegenerative diseases are a pathologically, clinically and genetically diverse group of diseases characterised by selective dysfunction, loss of synaptic connectivity and neurodegeneration, ​and are associated with the deposition of misfolded proteins in neurons and/or glia. Molecular studies have highlighted the role of conformationally altered proteins in the pathogenesis of neurodegenerative diseases and have paved the way for developing disease-specific biomarkers that capture and differentiate the main type/s of protein abnormality responsible for neurodegenerative diseases, some of which are currently used in clinical practice. These proteins follow sequential patterns of anatomical involvement and disease spread in the brain and may also be detected in peripheral organs. Recent studies suggest that glia are likely to have an important role in pathological spread throughout the brain and even follow distinct progression patterns from neurons. In addition to morphological and molecular approaches to the classification of these disorders, a further new stratification level incorporates the structure of protein filaments detected by cryogenic electron microscopy. Rather than occurring in isolation, combined deposition of tau, amyloid-β, α-synuclein and TDP-43 are frequently observed in neurodegenerative diseases and in the ageing brain. These can be overlooked, and their clinicopathological relevance is difficult to interpret. This review provides an overview of disease pathogenesis and diagnostic implications, recent molecular and ultrastructural classification of neurodegenerative diseases, how to approach ageing-related and mixed pathologies, ​and the importance of the protein-based classification system for practising neuropathologists and clinicians. This review also informs general pathologists about the relevance of ongoing full body autopsy studies to understand the spectrum and pathogenesis of neurodegenerative diseases.

Comparison of cerebral technetium-99m-ethyl cysteinate dimer perfusion in patients with dementia with Lewy bodies and Parkinson's disease dementia

OBJECTIVE

Dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD) are closely related neurodegenerative conditions within the Lewy body spectrum. The relationship between DLB and PDD remains debated, with ongoing discussion about whether they are distinct diseases or different manifestations of the same disorder. This study aimed to identify differences in cerebral perfusion patterns between DLB and PDD patients.

METHODS

Single-photon emission computed tomography (SPECT) ethyl cysteinate dimer (ECD) imaging was performed on patients diagnosed with DLB ( n  = 46) and PDD ( n  = 30). The data were acquired by two SPECT/computed tomography systems from two affiliated centers and were retrospectively recruited under the local ethics approval. Relative tracer uptake levels were calculated across 47 automatically determined regions of interest and 240 subregions. A two-sided Welch's t -test was employed to evaluate mean perfusion differences, with results further confirmed through a voxel-wise t -test mapping. The Benjamini-Hochberg procedure was used to adjust P -values for multiple comparisons.

RESULTS

The greatest difference in perfusion was in the left associative visual cortex in planes 34 and 36 and the right primary visual cortex in plane 34, with lower mean perfusion observed in PDD patients than those with DLB ( P  = 0.005).

CONCLUSION

No statistically significant differences in ECD perfusion were found between DLB and PDD patients. The greatest difference was in the visual cortices, where PDD patients suffered a greater loss of perfusion.

Resting-state electroencephalographic rhythms depend on sex in patients with dementia due to Parkinson's and Lewy Body diseases: An exploratory study

Parkinson's disease with dementia (PDD) and dementia with Lewy bodies (DLB) are more prevalent in males than females. Furthermore, they typically showed abnormally high delta (< 4 Hz) and low alpha (8-10 Hz) rhythms from resting-state electroencephalographic (rsEEG) activity. Here, we hypothesized that those abnormalities may depend on the patient's sex. An international database provided clinical-demographic-rsEEG datasets for cognitively unimpaired older (Healthy; N = 49; 24 females), PDD (N = 39; 13 females), and DLB (N = 38; 15 females) participants. Each group was stratified into matched female and male subgroups. The rsEEG rhythms were investigated across the individual rsEEG delta, theta, and alpha frequency bands based on the individual alpha frequency peak. The eLORETA freeware was used to estimate cortical rsEEG sources. In the Healthy group, widespread rsEEG alpha source activities were greater in the females than in the males. In the PDD group, widespread rsEEG delta source activities were lower and widespread rsEEG alpha source activities were greater in the females than in the males. In the DLB group, central-parietal rsEEG delta source activities were lower, and posterior rsEEG alpha source activities were greater in the females than in the males. These results suggest sex-dependent hormonal modulation of neuroprotective-compensatory neurophysiological mechanisms in PDD and DLB patients underlying the generation of rsEEG delta and alpha rhythms, which should be considered in the treatment of vigilance dysregulation in those patients.

Synaptosomal-Associated Protein 25 kDA (SNAP-25) Levels in Cerebrospinal Fluid: Implications for Alzheimer's Disease Diagnosis and Monitoring

Synaptic degeneration has been linked to cognitive decline. The presynaptic protein, synaptosomal-associated protein 25 kDA (SNAP-25), is crucial for synaptic transmission and has been suggested as a biomarker in Alzheimer's disease (AD). In the current study, we investigated the ability of SNAP-25 to differentiate between heterogenous dementia etiologies and whether SNAP-25 could be a staging marker in AD. SNAP-25 in the cerebrospinal fluid (CSF) from a retrospective (n = 187) and a prospective (n = 134) cohort was investigated with immunoprecipitation mass spectrometry (IP-MS) and single-molecule array (Simoa), respectively. Both cohorts consisted of healthy controls (HC) and patients with cognitive decline of different etiologies. CSF SNAP-25 concentration was higher in AD and non-neurodegenerative diseases (i.e., vascular dementia) compared with controls but did not differ between AD and non-AD neurodegenerative diseases. We found a trend toward an association between SNAP-25 and disease burden when comparing HC, mild cognitive impairment due to AD, and AD. CSF SNAP-25 concentrations were strongly associated with CSF phosphorylated tau (p-tau) concentrations, thus strengthening the link between synaptic dysfunction and tau pathophysiology in AD. Our initial findings suggest that SNAP-25 may be a potential biomarker for differentiating AD from dementia due to other etiologies. However, due to the significant association between SNAP-25 and p-tau proteins, the clinical utility of SNAP-25 as a diagnostic biomarker for AD may be limited, while SNAP-25 may be useful for monitoring disease progression or treatment response.

Louis EK, Knopman DS, Graff-Radford NR, Day GS, Ferman TJ, Kremers WK, Petersen RC, Boeve BF, Lowe VJ, Kantarci K. Longitudinal FDG-PET Metabolic Change Along the Lewy Body Continuum

Importance

Although 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) is a well-established cross-sectional biomarker of brain metabolism in dementia with Lewy bodies (DLB), the longitudinal change in FDG-PET has not been characterized.

Objective

To investigate longitudinal FDG-PET in prodromal DLB and DLB, including a subsample with autopsy data, and report estimated sample sizes for a hypothetical clinical trial in DLB.

Design, Setting, and Participants

Longitudinal case-control study with mean (SD) follow-up of 3.8 (2.3) years. Cases were recruited consecutively between 2007 and 2022 at a referral center and among the population. Patients with probable DLB or mild cognitive impairment with Lewy bodies (MCI-LB) were included. Individuals without cognitive impairment were included from a population-based cohort balanced on age and sex for comparison. All participants completed at least 1 follow-up assessment by design.

Exposure

Patients with MCI-LB and DLB.

Main Outcomes and Measures

Rate of change in FDG-PET was assessed as standardized uptake value ratios (SUVr). Clinical progression was assessed with the Clinical Dementia Rating Sum of Boxes (CDR-SB) score.

Results

Thirty-five patients with probable DLB, 37 patients with MCI-LB, and 100 individuals without cognitive impairment were included. The mean (SD) age of the DLB and MCI-LB groups combined (n = 72) was 69.6 (8.2) years; 66 patients (92%) were men and 6 (8%) were women. At follow-up, 18 participants (49%) with MCI-LB had progressed to probable DLB. Patients with MCI-LB had a faster decline in FDG-SUVr, compared with that of participants without cognitive impairment, in the posterior cingulate, occipital, parietal, temporal, and lateral frontal cortices. The same regions showed greater metabolic decline in patients with DLB than in participants without cognitive impairment, with the addition of anterior-middle cingulate, insula, and medial frontal orbital cortices. Rates of change in FDG-PET in these brain regions were combined into a region of interest (ROI) labeled longitudinal FDG-PET LB meta-ROI. The rate of change in FDG-SUVr in the meta-ROI correlated with the rate of change in CDR-SB, and sample size estimates were reported for potential clinical trials in DLB. Findings were confirmed in the subsample with neuropathologic confirmation (n = 20).

Conclusions and Relevance

This study found that brain hypometabolism begins to evolve during the prodromal stages of DLB with changes paralleling symptomatic progression. These data may inform clinical practice and trials planning to use FDG-PET for biologic staging, monitoring disease progression, and potentially assessing treatment response.

Salivary biomarkers for the molecular diagnosis of dementia with Lewy bodies

BackgroundDespite dementia with Lewy bodies (DLB) being the second most common form of neurodegenerative dementia, more than 80% of DLB cases are initially misdiagnosed. Alpha-synuclein (a-syn) and tau species have been detected in peripheral tissues and biological fluids of DLB patients and among different biological fluids, saliva represent an easely accessible and non-invasive source for biomarker detection.ObjectiveThis study aimed to investigate salivary a-syn and tau species as molecular disease biomarkers, assessing their potential in the diagnosis of DLB and in the differential diagnosis on respect to Alzheimer's disease (AD) and Parkinson's disease (PD).MethodsWe measured total and oligomeric a-syn, total-tau, and S199-phosphorylated-tau (pS199-tau) in the saliva of 21 DLB, 20 AD, 20 PD patients, and 20 healthy subjects (HS) using quantitative enzyme-linked immunosorbent assay (ELISA) analyses.ResultsSalivary total a-syn was not significantly changed between the different groups, whereas all pathological groups had a higher oligomeric a-syn concentration than HS. Salivary total-tau concentration was higher in all the pathological groups than HS, whereas the concentrations did not differ among patients' groups. Conversely, salivary levels of pS199-tau was higher in DLB and AD patients than in HS and PD patients. Both correlation matrix and principal component analysis showed that core clinical DLB features were related to a-syn pathology, while cognitive decline was associated with salivary levels of pS199-tau in both DLB and AD patients. Receiver operating characteristic analysis reported high diagnostic accuracy for both a-syn oligomers and pS199-tau, between DLB and HS, and an adequate accuracy between DLB and PD. Conversely, the diagnostic accuracy was not optimal between DLB patients and AD patients.ConclusionsThese findings provide preliminary evidence that salivary a-syn and tau species might be promising in identifying DLB patients on respect to PD patients and HS, while the diagnostic potential is limited on respect to AD.

Quantitative trait loci mapping of circulating metabolites in cerebrospinal fluid to uncover biological mechanisms involved in brain-related phenotypes

Genomic studies of molecular traits have provided mechanistic insights into complex disease, though these lag behind for brain-related traits due to the inaccessibility of brain tissue. We leveraged cerebrospinal fluid (CSF) to study neurobiological mechanisms in vivo, measuring 5543 CSF metabolites, the largest panel in CSF to date, in 977 individuals of European ancestry. Individuals originated from two separate cohorts including cognitively healthy subjects (n = 490) and a well-characterized memory clinic sample, the Amsterdam Dementia Cohort (ADC, n = 487). We performed metabolite quantitative trait loci (mQTL) mapping on CSF metabolomics and found 126 significant mQTLs, representing 65 unique CSF metabolites across 51 independent loci. To better understand the role of CSF mQTLs in brain-related disorders we integrated our CSF mQTL results with pre-existing summary statistics on brain traits, identifying 34 genetic associations between CSF metabolites and brain traits. Over 90% of significant mQTLs demonstrated colocalized associations with brain-specific gene expression, unveiling potential neurobiological pathways.

Engrams across diseases: Different pathologies - unifying mechanisms?

Memories are our reservoir of knowledge and thus, are crucial for guiding decisions and defining our self. The physical correlate of a memory in the brain is termed an engram and since decades helps researchers to elucidate the intricate nature of our imprinted experiences and knowledge. Given the importance that memories have for our lives, their impairment can present a tremendous burden. In this review we aim to discuss engram malfunctioning across diseases, covering dementia-associated pathologies, epilepsy, chronic pain and psychiatric disorders. Current neuroscientific tools allow to witness the emergence and fate of engram cells and enable their manipulation. We further suggest that specific mechanisms of mnemonic malfunction can be derived from engram cell readouts. While depicting the way diseases act on the mnemonic component - specifically, on the cellular engram - we emphasize a differentiation between forms of amnesia and hypermnesia. Finally, we highlight commonalities and distinctions of engram impairments on the cellular level across diseases independent of their pathogenic origins and discuss prospective therapeutic measures.

Brain 18F-fluorodeoxyglucose positron emission tomography: An efficient tool at the initial diagnosis of nonlesional late onset epilepsy

OBJECTIVE

This study evaluates the diagnostic performance and prognostic value of brain 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) at the initial diagnosis of patients with nonlesional late onset epilepsy (NLLOE).

METHODS

In this cohort study at the University Hospital of Nancy, France, newly diagnosed NLLOE patients, >50 years old, were consecutively included from June 2017 to January 2021 and systematically underwent brain 18F-FDG PET. They were categorized into four presumed etiological NLLOE subtypes: neurodegenerative subtype (NDS; patients with a diagnosis of neurodegenerative disease), microvascular subtype (MVS; patients with ≥3 cardiovascular risk factors and ≥2 vascular lesions on magnetic resonance imaging), inflammatory subtype (IFS; patients meeting international criteria for encephalitis), and unlabeled subtype (ULS). A systematic patient follow-up (at least 2 years) allowed assessment of cognitive outcomes under antiseizure medication by comparing for each patient the proportion of preserved/altered scores between initial and second neuropsychological assessment. Brain 18F-FDG PET was analyzed using a combined visual and semiquantitative approach at the individual level.

RESULTS

Eighty-seven patients were included (NDS, n = 18; MVS, n = 22; IFS, n = 7; ULS, n = 40). A normal 18F-FDG PET was observed in 46% of patients, with the final diagnosis of 88% of these patients excluding a neurodegenerative or inflammatory disorder. 18F-FDG PET had a negative predictive value of 94% for a cognitive decline at follow-up, similar for the overall population (n = 71) and the ULS population (n = 32). Moreover, a PET hypometabolic pattern suggestive of a neurodegenerative disorder was indicative of cognitive decline at follow-up in 74% of cases.

SIGNIFICANCE

18F-FDG PET as part of the initial diagnosis of NLLOE patients may have a significant impact on both NLLOE diagnosis and cognitive prognosis. For almost half of NLLOE patients, a normal 18F-FDG PET could help to exclude neurodegenerative and inflammatory epilepsy etiologies as well as future cognitive decline.

Applying Wearable Sensors and Machine Learning to the Diagnostic Challenge of Distinguishing Parkinson's Disease from Other Forms of Parkinsonism

Background/Objectives: Parkinson's Disease (PD) and other forms of parkinsonism share motor symptoms, including tremor, bradykinesia, and rigidity. The overlap in their clinical presentation creates a diagnostic challenge, as conventional methods rely heavily on clinical expertise, which can be subjective and inconsistent. This highlights the need for objective, data-driven approaches such as machine learning (ML) in this area. However, applying ML to clinical datasets faces challenges such as imbalanced class distributions, small sample sizes for non-PD parkinsonism, and heterogeneity within the non-PD group. Methods: This study analyzed wearable sensor data from 260 PD participants and 18 individuals with etiologically diverse forms of non-PD parkinsonism, which were collected during clinical mobility tasks using a single sensor placed on the lower back. We evaluated the performance of ML models in distinguishing these two groups and identified the most informative mobility tasks for classification. Additionally, we examined the clinical characteristics of misclassified participants and presented case studies of common challenges in clinical practice, including diagnostic uncertainty at the patient's initial visit and changes in diagnosis over time. We also suggested potential steps to address the dataset challenges which limited the models' performance. Results: Feature importance analysis revealed the Timed Up and Go (TUG) task as the most informative for classification. When using the TUG test alone, the models' performance exceeded that of combining all tasks, achieving a balanced accuracy of 78.2%, which is within 0.2% of the balanced diagnostic accuracy of movement disorder experts. We also identified differences in some clinical scores between the participants correctly and falsely classified by our models. Conclusions: These findings demonstrate the feasibility of using ML and wearable sensors for differentiating PD from other parkinsonian disorders, addressing key challenges in its diagnosis and streamlining diagnostic workflows.

Evaluation of cerebrospinal fluid levels of VAMP-2 and SNAP-25 in a dementia with Lewy bodies clinical cohort stratified by Alzheimer's pathophysiological biomarkers

BACKGROUND

Synaptic protein levels in cerebrospinal fluid (CSF) may represent much-needed objective biomarkers of cognitive impairment, disease progression and drug efficacy in patients with dementia with Lewy bodies (DLB). Soluble N-ethylmaleimide-sensitive factor attachment proteins receptors (SNARE) proteins, such as VAMP-2 and SNAP-25, are implicated in α-synuclein pathophysiology and CSF levels of these proteins are associated with pathophysiological biomarkers and cognitive decline in Alzheimer's disease (AD). The aim of the study was to compare CSF levels of VAMP-2 and SNAP-25 in patients with DLB to cognitively unimpaired controls and AD patients and study their association with cognitive performance and AD and neurodegeneration biomarkers.

METHODS

VAMP-2 and SNAP-25 were quantified in CSF from cognitively normal controls (n = 62), DLB (n = 44) and AD (n = 114) patients from the Sant Pau Initiative for Neurodegeneration (SPIN) cohort using homebrew Single Molecule Array assays (Simoa). The DLB group was stratified into two groups with ("DLB + AD", n = 28) or without AD co-pathology ("pure DLB", n = 16) using our validated cut-off for the CSF phosphorylated tau (p-tau)/Aβ42 ratio. We used linear regression to test for group differences (adjusting for age) and association with AD biomarkers. We used standardized w-scores of the cognitive tests to analyze the association of the synaptic markers with cognitive performance.

RESULTS

CSF VAMP-2 and SNAP-25 levels correlated across all groups (r = 0.71-0.9, p < 0.001). Both proteins were decreased in pure DLB (p < 0.001, p = 0.01) but increased in DLB + AD (p = 0.01, p = 0.02) compared to controls and showed good accuracy to discriminate pure DLB from DLB + AD (AUC = 0.84, 0.85). Both proteins were associated with CSF p-tau and total tau (t-tau) across all groups (r2 = 0.49-0.88, p < 0.001), with the Aβ42/40 ratio in DLB + AD (r2 = 0.29-0.36, p < 0.001) and in AD (r2 = 0.12-0.23, p < 0.001) and with CSF neurofilament-light chain (NfL) in controls (r²=0.10-0.11, p < 0.001-0.01) and AD patients (r²=0.01-0.08, p = 0.01 - 0.001). SNAP-25 was associated with CSF NfL in the DLB + AD group (r²=0.15, p = 0.02). CSF VAMP-2 and SNAP-25 were associated with phonemic fluency in pure DLB (r2 = 0.39 - 0.28, p = 0.01-0.03) and SNAP-25 with the Clock drawing test and the MMSE in DLB + AD (adj.r2 = 0.15 - 0.14, p = 0.03-0.03) and DLB (adj.r2 = 0.12 - 0.08, p = 0.02-0.04) groups.

CONCLUSIONS

CSF VAMP-2 and SNAP-25 are promising surrogate markers of synapse degeneration in DLB. However, care should be taken when interpreting CSF levels of these synaptic markers in DLB in light of the confounding effect of AD pathophysiological markers.

Unraveling the clinical-pathological correlations of subjects with isolated and mixed neurodegenerative processes in the National Alzheimer's Coordinating Center dataset

Although Alzheimer disease neuropathologic change (ADNC) is the most common pathology underlying clinical dementia, the presence of multiple comorbid neuropathologies is increasingly being recognized as a major contributor to the worldwide dementia burden. We analyzed 1051 subjects with specific combinations of isolated and mixed pathologies and conducted multivariate logistic regression analysis on a cohort of 4624 cases with mixed pathologies to systematically explore the independent cognitive contributions of each pathology. Alzheimer disease neuropathologic change and limbic-predominant age-related TDP-43 encephalopathy neuropathologic change (LATE-NC) were both associated with a primary clinical diagnosis of Alzheimer disease (AD) and were characterized by an amnestic dementia phenotype, while only ADNC associated with logopenic variant primary progressive aphasia (PPA). In subjects with ADNC and comorbid LATE-NC, Lewy body disease, and/or cerebrovascular disease, the clinical phenotype was usually diagnosed during life as "Probable AD." Conversely, the combination of ADNC with frontotemporal lobar degeneration with TDP-43, progressive supranuclear palsy (PSP), or corticobasal degeneration (CBD) resulted in a mixed clinical picture, with variable features of amnestic dementia, PPA subtypes, behavioral variant FTD, PSP syndrome, and CBD syndrome. These findings elucidate the cumulative effects of mixed pathologies and provide insights into interactions between neurodegenerative pathologies contributing to a variety of clinical dementia presentations.

Comparison of Quantitative-Electroencephalogram (q-EEG) Measurements Between Patients of Dementia with Lewy Bodies (DLB) and Parkinson Disease Dementia (PDD)

Dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD) are synucleinopathy syndromes with similar symptom profiles that are distinguished clinically based on the arbitrary rule of the time of symptom onset. Identifying reliable electroencephalographic (EEG) biomarkers would provide a precise method for better diagnosis, treatment, and monitoring of treatment response in these two types of dementia. From April 2015 to March 2021, the records of new referrals to a neurology clinic were retrospectively reviewed and 28 DLB(70.3% male) and 20 PDD (80.8% male) patients with appropriate EEG were selected for this study. Artifact-free 60-s EEG signals (21 channels) at rest with eyes closed were analyzed using EEGLAB, and regional spectral power ratios were extracted. Marked diffuse slowing was found in DLB patients compared to PDD patients in all regions in terms of decrease in alpha and increase in theta band. Although, these findings demean between groups after adjusting for MMSE scores, the significant difference still remained in terms of the mean relative alpha powers, particularly in the anterior and central regions. QEEG measures may have the potential to discriminate between these two syndromes. However, further prospective and longitudinal studies are required to improve the early differentiation of these dementia syndromes and to elucidate the underlying causes and pathogenesis and specific treatment.

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.

Molecular Insights into α-Synuclein Fibrillation: A Raman Spectroscopy and Machine Learning Approach

The aggregation of α-synuclein is crucial to the development of Lewy body diseases, including Parkinson's disease and dementia with Lewy bodies. The aggregation pathway of α-synuclein typically involves a defined sequence of nucleation, elongation, and secondary nucleation, exhibiting prion-like spreading. This study employed Raman spectroscopy and machine learning analysis, alongside complementary techniques, to characterize the biomolecular changes during the fibrillation of purified recombinant wild-type α-synuclein protein. Monomeric α-synuclein was produced, purified, and subjected to a 7-day fibrillation assay to generate preformed fibrils. Stages of α-synuclein fibrillation were analyzed using Raman spectroscopy, with aggregation confirmed through negative staining transmission electron microscopy, mass spectrometry, and light scattering analyses. A machine learning pipeline incorporating principal component analysis and uniform manifold approximation and projection was used to analyze the Raman spectral data and identify significant peaks, resulting in differentiation between sample groups. Notable spectral shifts in α-synuclein were found in various stages of aggregation. Early changes (D1) included increases in α-helical structures (1303, 1330 cm-1) and β-sheet formation (1045 cm-1), with reductions in COO- and CH2 bond regions (1406, 1445 cm-1). By D4, these structural shifts persist with additional β-sheet features. At D7, a decrease in β-sheet H-bonding (1625 cm-1) and tyrosine ring breathing (830 cm-1) indicates further structural stabilization, suggesting a shift from initial helical structures to stabilized β-sheets and aggregated fibrils. Additionally, alterations in peaks related to tyrosine, alanine, proline, and glutamic acid were identified, emphasizing the role of these amino acids in intramolecular interactions during the transition from α-helical to β-sheet conformational states in α-synuclein fibrillation. This approach offers insight into α-synuclein aggregation, enhancing the understanding of its role in Lewy body disease pathophysiology and potential diagnostic relevance.

Clinical implication of anemia in older patients with dementia with lewy bodies

AIM

This research sought to investigate the possible connection between anemia and various parameters of comprehensive geriatric assessment in elderly individuals diagnosed with Dementia with Lewy Bodies (DLB). To our knowledge, this investigation represents the first attempt to examine how anemia impacts patients suffering from DLB.

METHODS

This cross-sectional study encompassed 147 DLB patients from a single geriatric outpatient clinic. The study defined anemia as hemoglobin levels under 12 g/dL for women and 13 g/dL for men. Patients' demographic information, coexisting medical conditions, and results from comprehensive geriatric evaluations were also recorded.

RESULTS

Participants in the study had an average age of 85.4 ± 7.1 years. Anemia was present in 46.9% of the patients. Significant disparities were noted between individuals with and without anemia regarding the occurrence of congestive heart failure (CHF), polypharmacy, geriatric depression, and insomnia (all p < 0.05). After controlling for age, gender, and CHF in the multivariate analysis, the association between anemia and both the quantity of medications used [OR: 1.15 (95% CI:1.01-1,31)] and Geriatric Depression Scale-15 scores [OR: 0.88, 95% CI: 0.78-0.98] remained statistically significant (p < 0.05) when comparing anemic patients to non-anemic individuals.

CONCLUSION

In the present study almost one in two older patients with DLB were anemic. Anemia is associated with presence of CHF, higher number of drugs and depressive mood in DLB. It is recommended that healthcare providers should recognize the importance of anemia and its associated effects when treating older adults with DLB. This approach may lead to more effective management and treatment of this complex condition.

Multi-atlas multi-modality morphometry analysis of the South Texas Alzheimer's Disease Research Center postmortem repository

Histopathology provides critical insights into the neurological processes inducing neurodegenerative diseases and their impact on the brain, but brain banks combining histology and neuroimaging data are difficult to create. As part of an ongoing global effort to establish new brain banks providing both high-quality neuroimaging scans and detailed histopathology examinations, the South Texas Alzheimer's Disease Re- search Center postmortem repository was recently created with the specific purpose of studying comorbid dementias. As the repository is reaching a milestone of two hundred brain donations and a hundred curated MRI sessions are ready for processing, robust statistical analyses can now be conducted. In this work, we report the very first morphometry analysis conducted with this new data set. We describe the processing pipelines that were specifically developed to exploit the available MRI sequences, and we explain how we addressed several postmortem neuroimaging challenges, such as the separation of brain tissues from fixative fluids, the need for updated brain atlases, and the tissue contrast changes induced by brain fixation. In general, our results establish that a combination of structural MRI sequences can provide enough informa- tion for state-of-the-art Deep Learning algorithms to almost perfectly separate brain tissues from a formalin buffered solution. Regional brain volumes are challenging to measure in postmortem scans, but robust estimates sensitive to sex differences and age trends, reflecting clinical diagnosis, neuropathology findings, and the shrinkage induced by tissue fixation can be obtained. We hope that the new processing methods developed in this work, such as the lightweight Deep Networks we used to identify the formalin signal in multimodal MRI scans and the MRI synthesis tools we used to fix our anisotropic resolution brain scans, will inspire other research teams working with postmortem MRI scans.

From mechanisms to future therapy: a synopsis of isolated REM sleep behavior disorder as early synuclein-related disease

Parkinson disease (PD), dementia with Lewy bodies (DLB) and multiple system atrophy are synucleinopathies, characterized by neuronal loss, gliosis and the abnormal deposition of α-synuclein in vulnerable areas of the nervous system. Neurodegeneration begins however several years before clinical onset of motor, cognitive or autonomic symptoms. The isolated form of REM sleep behavior disorder (RBD), a parasomnia with dream enactment behaviors and excessive muscle activity during REM sleep, is an early stage synucleinopathy. The neurophysiological hallmark of RBD is REM sleep without atonia (RWSA), i.e. the loss of physiological muscle atonia during REM sleep. RBD pathophysiology is not fully clarified yet, but clinical and basic science suggest that ɑ-syn pathology begins in the lower brainstem where REM atonia circuits are located, including the sublaterodorsal tegmental/subcoeruleus nucleus and the ventral medulla, then propagates rostrally to brain regions such as the substantia nigra, limbic system, cortex. Genetically, there is only a partial overlap between RBD, PD and DLB, and individuals with iRBD may represent a specific subpopulation. A genome-wide association study identified five loci, which all seem to revolve around the GBA1 pathway. iRBD patients often show subtle motor, cognitive, autonomic and/or sensory signs, neuroimaging alterations as well as biofluid and tissue markers of neurodegeneration (in particular pathologic α-synuclein aggregates), which can be useful for risk stratification. Patients with iRBD represent thus the ideal population for neuroprotective/neuromodulating trials. This review provides insights into these aspects, highlighting and substantiating the central role of iRBD in treatment development strategies for synucleinopathies.

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.

Detection of Alzheimer Neuropathology in Alzheimer and Non-Alzheimer Clinical Syndromes With Blood-Based Biomarkers

Importance

Blood-based biomarkers for Alzheimer disease (AD) are clinically available, but their value is not well understood in syndromes typically associated with frontotemporal lobar degeneration syndromes (FTLD).

Objective

To investigate the clinical importance and detectability of AD in FTLD-related neurodegenerative syndromes using 3 plasma biomarkers, phosphorylated tau 217 (p-tau217), neurofilament light chain (NfL), and glial fibrillary acidic protein (GFAP).

Design, Setting, and Participants

This clinicopathological study took place at the University of California San Francisco Alzheimer Disease Research Center from August 2008 to July 2022. Autopsied individuals with clinical evaluation and neuropathological examination, diagnosed with clinical syndromes related to AD (n = 125), frontotemporal lobar degeneration (FTLD; n = 198), or cognitively unimpaired (CU) at the time of evaluation (n = 16) were included.

Exposures

AD-related or FTLD-related clinical syndromes or CU.

Main Outcomes and Measures

P-tau217, NfL, and GFAP were measured with single-molecule array (SIMOA). AD was defined as intermediate or high AD neuropathological change (ADNC) at autopsy. Clinical biomarker associations were evaluated using linear regressions. Imaging analyses used bayesian linear mixed-effects modeling.

Results

A total of 349 individuals (191 [55%] male; mean [SD] age at death, 72 [11] years) were included. AD was common in both AD-related syndromes (110/125 [88%]) and FTLD-related syndromes (45/198 [23%]). Neuropathological stage at autopsy was higher in AD-related syndromes (high ADNC: 82/88 [93%] AD vs 13/23 [56%] FTLD), and AD was frequently considered a copathology in FTLD-related syndromes (30/198 [15%]). Plasma p-tau217 concentrations were higher in AD-related syndromes (mean [SD], 0.28 [0.16] pg/mL) than FTLD-related syndromes (mean [SD], 0.10 [0.09] pg/mL) (P < .05). Plasma p-tau217 concentrations were highest in atypical AD-related syndromes (mean [SD], 0.33 [0.02] pg/mL), followed by typical late-onset amnestic syndromes (mean [SD], 0.27 [0.03] pg/mL). FTLD-related syndromes with AD (mean [SD], 0.19 [0.02] pg/mL) were higher compared to without (mean [SD], 0.07 [0.00] pg/mL). Plasma p-tau217 detected AD neuropathology across syndromes (area under the receiver operating characteristic curve [AUC], 0.95; 95% CI, 0.93-0.97), with slightly better performance in AD-related syndromes (AUC, 0.98; 95% CI, 0.95-1.00) compared to FTLD-related syndromes (AUC, 0.89; 95% CI, 0.83-0.94). NfL and GFAP had lower performance for detecting AD (AUC, 0.73; 95% CI, 0.68-0.78 and AUC, 0.75; 95% CI, 0.67-0.80, respectively) and added little to no diagnostic value either alone or in combinations with p-tau217. The presence of AD in FTLD-related syndromes was associated with lower Mini-Mental State Examination score (mean [SD], -2.90 [1.09]; P < .05), worse performance on memory (mean [SD] z score, -0.64 [0.32]), executive (mean [SD] z score, -0.74 [0.19]), and visuospatial composites (mean [SD] z score, -0.88 [0.37]) as well as increased rates of posterior cortical atrophy.

Conclusion

Clinically relevant AD was prevalent across neurodegenerative syndromes and detectable with plasma p-tau217. Plasma p-tau217 may be a useful tool to investigate the clinical impact of AD copathology in non-AD neurodegenerative syndromes, including the effect of disease-modifying therapies.

Analyzing Information Exchange in Parkinson's Disease via Eigenvector Centrality: A Source-Level Magnetoencephalography Study

Background: Parkinson's disease (PD) is a progressive neurodegenerative disorder that manifests through motor and non-motor symptoms. Understanding the alterations in brain connectivity associated with PD remains a challenge that is crucial for enhancing diagnosis and clinical management. Methods: This study utilized Magnetoencephalography (MEG) to investigate brain connectivity in PD patients compared to healthy controls (HCs) by applying eigenvector centrality (EC) measures across different frequency bands. Results: Our findings revealed significant differences in EC between PD patients and HCs in the alpha (8-12 Hz) and beta (13-30 Hz) frequency bands. To go into further detail, in the alpha frequency band, PD patients in the frontal lobe showed higher EC values compared to HCs. Additionally, we found statistically significant correlations between EC measures and clinical impairment scores (UPDRS-III). Conclusions: The proposed results suggest that MEG-derived EC measures can reveal important alterations in brain connectivity in PD, potentially serving as biomarkers for disease severity.

Systemic inflammatory markers in ageing, Alzheimer's disease and other dementias

Systemic inflammation with alterations in inflammatory markers is involved in ageing and Alzheimer's disease. However, few studies have investigated the longitudinal trajectories of systemic inflammatory markers during ageing and Alzheimer's disease, and specific markers contributing to Alzheimer's disease remain undetermined. In this study, a longitudinal cohort (cohort 1: n = 290; controls, 136; preclinical Alzheimer's disease, 154) and a cross-sectional cohort (cohort 2: n = 351; controls, 62; Alzheimer's disease, 63; vascular dementia, 58; Parkinson's disease dementia, 56; behavioural variant frontotemporal dementia, 57; dementia with Lewy bodies, 55) were included. Plasma levels of inflammatory markers were measured every 2 years during a 10-year follow-up in the longitudinal cohort and once in the cross-sectional cohort. The study demonstrated that the inflammatory markers significantly altered during both ageing and the development of Alzheimer's disease. However, only complement C3, interleukin-1β and interleukin-6 exhibited significant changes in participants with preclinical Alzheimer's disease, and their longitudinal changes were significantly associated with the development of Alzheimer's disease compared to controls over the 10-year follow-up. In the cross-sectional cohort, complement C3 demonstrated specificity to Alzheimer's disease, while interleukin-1β and interleukin-6 were also altered in other dementias. The study provides a new perspective on the involvement of inflammatory markers in the ageing process and the development of Alzheimer's disease, implying that regulating inflammation may have a pivotal role in promoting successful ageing and in the prevention and treatment of Alzheimer's disease.

Plasma p-tau217 in Alzheimer's disease: Lumipulse and ALZpath SIMOA head-to-head comparison

Plasma phosphorylated-tau217 (p-tau217) has been shown to be one of the most accurate diagnostic markers for Alzheimer's disease. No studies have compared the clinical performance of p-tau217 as assessed by the fully automated Lumipulse and single molecule array (SIMOA) AlZpath p-tau217. The study included 392 participants, 162 with Alzheimer's disease, 70 with other neurodegenerative diseases with CSF biomarkers and 160 healthy controls. Plasma p-tau217 levels were measured using the Lumipulse and ALZpath SIMOA assays. The ability of p-tau217 assessed by both techniques to discriminate Alzheimer's disease from other neurodegenerative diseases and controls was investigated using receiver operating characteristic analyses. The p-tau217 levels measured by the two techniques demonstrated a strong correlation, showing a consistent relationship with CSF p-tau181 levels. In head-to-head comparison, Lumipulse and SIMOA showed similar diagnostic accuracy for differentiating Alzheimer's disease from other neurodegenerative diseases [area under the curve (AUC) 0.952, 95% confidence interval (CI) 0.927-0.978 versus 0.955, 95% CI 0.928-0.982, respectively] and healthy controls (AUC 0.938, 95% CI 0.910-0.966 and 0.937, 95% CI 0.907-0.967 for both assays). This study demonstrated the high precision and diagnostic accuracy of p-tau217 for the clinical diagnosis of Alzheimer's disease using fully automated or semi-automated techniques.

Detection of the Cingulate Island Sign by Early Perfusion Imaging in Dopamine Transporter SPECT With Multiple-Pinhole Collimators

ABSTRACT

Multiple-pinhole collimators provide considerable improvement of SPECT system count sensitivity. This case report suggests that SPECT with brain-specific multiple-pinhole collimators enables cerebral perfusion imaging with diagnostic quality by an early 12 minutes scan immediately after injection of a standard dose of the dopamine transporter ligand 123I-FP-CIT. Thus, 123I-FP-CIT SPECT with multiple-pinhole collimators could assess nigrostriatal degeneration (late image) and extrastriatal involvement (early perfusion image) during the same imaging session. The early image may serve as an alternative to FDG PET in patients with suspicion of an atypical neurodegenerative parkinsonian syndrome. This could streamline diagnostic workflows by reducing the need for additional imaging modalities.

Agreement of cerebrospinal fluid biomarkers and amyloid-PET in a multicenter study

Core Alzheimer's disease (AD) cerebrospinal fluid (CSF) biomarkers have shown incomplete agreement with amyloid-positron emission tomography (PET). Our goal was to analyze the agreement between AD CSF biomarkers and amyloid-PET in a multicenter study. Retrospective multicenter study (5 centers). Participants who underwent both CSF biomarkers and amyloid-PET scan within 18 months were included. Clinical diagnoses were made according to latest diagnostic criteria by the attending clinicians. CSF Amyloid Beta1-42 (Aβ1-42, A), phosphorliated tau 181 (pTau181, T) and total tau (tTau, N) biomarkers were considered normal (-) or abnormal ( +) according to cutoffs of each center. Amyloid-PET was visually classified as positive/negative. Agreement between CSF biomarkers and amyloid-PET was analyzed by overall percent agreement (OPA). 236 participants were included (mean age 67.9 years (SD 9.1), MMSE score 24.5 (SD 4.1)). Diagnoses were mild cognitive impairment or dementia due to AD (49%), Lewy body dementia (22%), frontotemporal dementia (10%) and others (19%). Mean time between tests was 5.1 months (SD 4.1). OPA between single CSF biomarkers and amyloid-PET was 74% for Aβ1-42, 75% for pTau181, 73% for tTau. The use of biomarker ratios improved OPA: 87% for Aβ1-42/Aβ1-40 (n = 155), 88% for pTau181/Aβ1-42 (n = 94) and 82% for tTau/Aβ1-42 (n = 160). A + T + N + cases showed the highest agreement between CSF biomarkers and amyloid-PET (96%), followed by A-T-N- cases (89%). Aβ1-42/Aβ1-40 was a better marker of cerebral amyloid deposition, as identified by amyloid tracers, than Aβ1-42 alone. Combined biomarkers in CSF predicted amyloid-PET result better than single biomarkers.

Validation of Spatial Orientation Screening questionnaire for use in memory clinic patients

BACKGROUND

Spatial orientation is required for independent mobility in society. Deficits in spatial orientation can be an early symptom of Alzheimer's disease and other dementias, and there is a need for brief assessment tools to identify impairments.

OBJECTIVE

The aim of this study was to evaluate the construct and known-group validity of our newly developed Spatial Orientation Screening (SOS) questionnaire.

METHODS

We included 132 patients with subjective cognitive decline (n = 16), mild cognitive impairment (n = 32), or all-cause dementia (n = 84) from a memory clinic and a reference group of cognitively unimpaired older adults (n = 108). The patients and their next-of-kin answered the self- and proxy-rated versions of the 4-item SOS (0-8 points) and the 10-item Questionnaire of Everyday Navigational Ability (QuENA, 0-30 points). The patients also performed the Floor Maze Test (FMT) for performance-based spatial abilities.

RESULTS

Mean ages (SD) of the patient and reference groups were 68.6 (±7.6) years and 73.7 (±6.7) years, respectively. Construct validity between self-rated versions of the SOS and QuENA was satisfactory with rs = 0.66, between the proxy-rated versions rs = 0.61, and between the proxy-reported SOS and FMT rs = 0.49 (all p < 0.001). Known-group validity was also acceptable, with significantly higher median (IQR) SOS self-reported scores in patients 1.0 (2.0) compared to the reference group 0.2 (0.5) points, (p < 0.001). Informants reported more severe impairments compared to the patients' self-reports on both SOS and QuENA (both p < 0.001).

CONCLUSIONS

The SOS had satisfactory validity for use as a screening instrument for assessment of spatial orientation in memory clinic patients.

A neuropathology case report of a woman with Down syndrome who remained cognitively stable: Implications for resilience to neuropathology

INTRODUCTION

Aging adults with Down syndrome (DS) accumulate Alzheimer's disease (AD) neuropathology, including amyloid beta plaques and neurofibrillary tangles, by age 40.

METHODS

We present findings from an individual with DS who remained cognitively stable despite AD neuropathology. Clinical assessments, fluid biomarkers, neuroimaging, and neuropathological examinations were conducted to characterize her condition.

RESULTS

Her apolipoprotein E was ε2/ε3 and genome-wide association study data indicated mosaicism. Neuroimaging revealed stable yet elevated amyloid and moderately elevated tau levels, while neuropathology indicated intermediate AD neuropathologic change with Lewy body and cerebrovascular pathologies. The participant demonstrated stable cognitive functioning in her 60s, potentially attributed to genetic variations, cognitive resilience, and environmental enrichment.

DISCUSSION

These findings emphasize the complexity of AD progression in DS. Further investigation into factors influencing cognitive resilience in individuals with DS is warranted. Understanding the mechanisms underlying cognitive stability in DS could offer insights into resilience to AD neuropathology in people with DS and inform future interventions.

HIGHLIGHTS

Findings from clinical assessments, fluid biomarkers, genotyping, neuroimaging, and neuropathological examinations of an individual with Down syndrome (DS) who remained cognitively stable despite Alzheimer's disease (AD) neuropathology are presented. Neuroimaging revealed stable yet elevated amyloid profiles and moderately elevated tau levels, while neuropathology indicated intermediate AD neuropathologic change with Lewy body and cerebrovascular pathologies. Despite the presence of AD pathology, the participant demonstrated intact cognitive functioning, potentially attributed to genetic variations, cognitive resilience, and environmental enrichment, emphasizing the complexity of AD progression in DS.

Distinguishing Prodromal Dementia With Lewy Bodies From Prodromal Alzheimer Disease: A Longitudinal Study

Background and Objectives

It can be clinically challenging to differentiate dementia with Lewy bodies (DLB) and Alzheimer disease (AD). As potential therapies emerge with the goal of slowing or halting misfolded protein aggregation, it is imperative to be able to identify individuals before the disease becomes disabling. Differentiating between DLB and AD in the preclinical or prodromal phase of DLB and AD becomes more important. Studies are needed to validate the proposed criteria for prodromal DLB.

Methods

Longitudinal data were obtained from the Uniform Data Set of the National Alzheimer's Coordinating Center. Included participants had a baseline diagnosis of normal or mild cognitive impairment and a consecutive 2-year follow-up diagnosis of DLB or AD. We examined whether core DLB clinical features, supportive neuropsychiatric features, and neuropsychological data in the 2 years preceding the dementia diagnosis distinguished DLB from AD.

Results

We identified 143 participants with DLB and 429 age-matched/sex-matched participants with AD. The presence of 2 or more core DLB features in the year before dementia diagnosis yielded the greatest AUC (0.793; 95% CI 0.748-0.839) in distinguishing prodromal DLB from prodromal AD. Sleep disturbances, hallucinations, and a cognitive profile of worse processing speed, attention, and visuoconstruction performance were evident at least 2 years before the dementia diagnosis in DLB compared with AD.

Discussion

Data from this multisite, longitudinal, well-characterized research North American cohort support the validity of the recently published criteria for prodromal DLB. In the prodromal stage, patients who subsequently develop DLB are more likely to have core DLB clinical features and worse attention, processing speed, and visuospatial performance than those who go on to develop AD. Differentiation of DLB and AD before dementia emerges provides an opportunity for early, disease-specific intervention and overall management.

Identifying gait differences between Alzheimer's disease and dementia with Lewy bodies and their associations with regional amyloid deposition

INTRODUCTION

We aimed to compare gait between individuals with Alzheimer's disease (AD), dementia with Lewy bodies (DLB), and cognitively unimpaired (CU) individuals and to evaluate the association between gait and regional amyloid beta (Aβ) burden in AD and DLB.

METHODS

We included 420 participants (70 AD, 70 DLB, 280 CU) in the Mayo Clinic Study of Aging (MCSA). Gait was assessed using a pressure-sensor walkway. Aβ deposition was analyzed with Pittsburgh compound B (PiB) positron emission topography (PET).

RESULTS

The DLB group had reduced stride velocity, step length, and stride width variability, as well as increased double support percentage (%DS) and variability in step length, swing time, and step time compared to the AD and CU groups. Aβ burden was not associated with any gait outcomes.

DISCUSSION

This study provides additional evidence that gait differs between AD and DLB. Larger studies are needed to investigate associations between Aβ burden and gait outcomes in dementia.

HIGHLIGHTS

Gait was more impaired in dementia than in cognitively unimpaired (CU) controls. Compared with Alzheimer's disease (AD), Dementia with Lewy bodies (DLB) had more impaired pace, variability, and postural control. Step length and double support (%) distinguished DLB and AD with moderate accuracy.

Plasma phosphorylated tau and neuropsychiatric symptoms in dementia with Lewy bodies

INTRODUCTION

Neuropsychiatric symptoms (NPSs) are common in dementia with Lewy bodies (DLB) but their neurobiological mechanisms are poorly understood.

METHODS

NPSs and cognition were assessed annually in participants (DLB n = 222; Alzheimer's disease [AD] n = 125) from the European DLB (E-DLB) Consortium, and plasma phosphorylated tau-181 (p-tau181) and p-tau231 concentrations were measured at baseline.

RESULTS

Hallucinations, delusions, and depression were more common in DLB than in AD and, in a subgroup with longitudinal follow-up, persistent hallucinations and NPSs were associated with lower p-tau181 and p-tau231 in DLB. In adjusted linear mixed-effects models, hallucinations at baseline were associated with greater longitudinal cognitive impairment in DLB, with a significant interaction with p-tau231.

DISCUSSION

Higher p-tau181 and p-tau231 levels were associated with a lower longitudinal risk of NPSs and hallucinations in early-stage DLB. However, the interaction between hallucinations and p-tau231 suggests that when AD co-pathology and hallucinations do co-exist in DLB that they may synergistically exacerbate cognitive decline.

HIGHLIGHTS

Neuropsychiatric symptoms (NPSs) were more common in dementia with Lewy bodies (DLB) than in Alzheimer's disease (AD). Lower plasma phosphorylated tau-231 (p-tau231) and p-tau181 levels were associated with persistent hallucinations in DLB. Lower plasma p-tau231 and p-tau181 levels were associated with an increased risk of persistent NPSs in early DLB. Hallucinations at baseline were associated with greater cognitive dysfunction in DLB, and there was an interaction with p-tau231.

From onset to advancement: the temporal spectrum of α-synuclein in synucleinopathies

This review provides an in-depth analysis of the complex role of alpha-synuclein (α-Syn) in the development of α-synucleinopathies, with a particular focus on its structural diversity and the resulting clinical variability. The ability of α-Syn to form different strains or polymorphs and undergo various post-translational modifications significantly contributes to the wide range of symptoms observed in disorders such as Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA), as well as in lesser-known non-classical α-synucleinopathies. The interaction between genetic predispositions and environmental factors further complicates α-synucleinopathic disease pathogenesis, influencing the disease-specific onset and progression. Despite their common pathological hallmark of α-Syn accumulation, the clinical presentation and progression of α-synucleinopathies differ significantly, posing challenges for diagnosis and treatment. The intricacies of α-Syn pathology highlight the critical need for a deeper understanding of its biological functions and interactions within the neuronal environment to develop targeted therapeutic strategies. The precise point at which α-Syn aggregation transitions from being a byproduct of initial disease triggers to an active and independent driver of disease progression - through the propagation and acceleration of pathogenic processes - remains unclear. By examining the role of α-Syn across various contexts, we illuminate its dual role as both a marker and a mediator of disease, offering insights that could lead to innovative approaches for managing α-synucleinopathies.

Tracer kinetic model detecting heterogeneous blood-brain barrier permeability to water and contrast agent in Alzheimer's disease and dementia with Lewy bodies

INTRODUCTION

Blood-brain barrier (BBB) breakdown is essential in Alzheimer's disease (AD) and dementia with Lewy bodies (DLB), whereas the variability in BBB permeability to water and contrast agent is less clear.

METHODS

We investigated BBB permeability to water and contrast agent simultaneously using a novel tracer kinetic model for dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in 42 AD patients, 22 DLB patients, and 22 healthy controls. All participants underwent clinical, cognitive, and MRI assessments.

RESULTS

AD patients exhibited a significant reduction in the water exchange rates across the BBB, whereas DLB patients showed a significant increase in BBB permeability to contrast agent. Moreover, BBB permeability to both water and contrast agent in multiple brain regions demonstrated correlations with clinical severity.

DISCUSSION

The simultaneous evaluation of BBB permeability to water and contrast agent based on the proposed model highlights the heterogeneous patterns of BBB breakdown in AD and DLB.

HIGHLIGHTS

We measured blood-brain barrier (BBB) permeability to water and contrast agent based on dynamic contrast-enhanced magnetic resonance imaging. Alzheimer's disease (AD) is characterized by lower water exchange rates across the BBB. Dementia with Lewy bodies exhibits higher BBB permeability to contrast agent. BBB permeability is related to cognitive impairment and disease burden. BBB permeability to water was negatively associated with that to contrast agent.

Frontotemporal Dementia Differential Diagnosis in Clinical Practice: A Single-Center Retrospective Review of Frontal Behavioral Referrals

Background and Objectives

Many neurodegenerative syndromes present with impairment of frontal networks, especially frontoinsular networks affecting social and emotional cognition. People presenting with frontal network impairments may be considered for a frontotemporal dementia (FTD) diagnosis. We sought to examine the diagnostic mix of patients referred with frontal network impairments to a single cognitive neurology service.

Methods

A retrospective review was conducted of all patients seen between January 2010 and December 2019 at the Eastern Cognitive Disorders Clinic, a quaternary cognitive neurology clinic in Melbourne, Australia. Patients were included if they met the following criteria: (1) were referred for suspected FTD or with a preexisting diagnosis of a FTD syndrome, (2) were referred for 'frontal behaviors' (i.e., disinhibition, disorganization, poor judgment, loss of empathy, apathy) and/or had an informant report of behavior change, and (3) had available referral documents and clinical consensus diagnosis. Referral diagnosis was compared against final diagnosis adjudicated by a consensus multidisciplinary team. Case details including age of symptom onset, Cambridge Behavioural Inventory-Revised scores, psychiatric history, and Charlson Comorbidity Index were compared against the final diagnosis.

Results

In total, 161 patients aged 42-82 years (mean = 64.5, SD = 9.0; 74.5% men) met inclusion criteria. The commonest final diagnosis was a FTD syndrome (44.6%: 26.7% behavioral variant FTD (bvFTD), 9.3% progressive supranuclear palsy, 6.2% semantic dementia, 1.2% corticobasal syndrome, and 1.2% FTD/motor neuron disease). A primary psychiatric disorder (PPD) was the next commonest diagnosis (15.5%), followed by vascular cognitive impairment (VCI, 10.6%), Alzheimer disease (AD, 9.9%), and other neurologic diagnoses (6.2%). A final diagnosis of bvFTD was associated with higher rates of medical comorbidities and more eating behavior abnormalities compared with a diagnosis of PPD. Screening cognitive tests and preexisting psychiatric history did not distinguish these 2 groups.

Discussion

A broad spectrum of neurologic and psychiatric disorders may present with impairments to frontal networks. Almost half of patients referred had a final FTD syndrome diagnosis, with bvFTD the commonest final diagnosis. People with PPD, VCI, and AD present with similar clinical profiles but are distinguishable using MRI and FDG-PET imaging. Medical and psychiatric comorbidities are common in people with bvFTD.

Behavioral disorders in dementia with Lewy bodies: old and new knowledge

Dementia with Lewy bodies (DLB), the second most common primary degenerative neurocognitive disorder after Alzheimer disease, is frequently preceded by REM sleep behavior disorders (RBD) and other behavioral symptoms, like anxiety, irritability, agitation or apathy, as well as visual hallucinations and delusions, most of which occurring in 40-60% of DLB patients. Other frequent behavioral symptoms like attention deficits contribute to cognitive impairment, while attention-deficit/hyperactivity disorder (ADHD) is a risk factor for DLB. Behavioral problems in DLB are more frequent, more severe and appear earlier than in other neurodegenerative diseases and, together with other neuropsychiatric symptoms, contribute to impairment of quality of life of the patients, but their pathophysiology is poorly understood. Neuroimaging studies displayed deficits in cholinergic brainstem nuclei and decreased metabolism in frontal, superior parietal regions, cingulate gyrus and amygdala in DLB. Early RBD in autopsy-confirmed DLB is associated with lower Braak neuritic stages, whereas those without RBD has greater atrophy of hippocampus and increased tau burden. αSyn pathology in the amygdala, a central region in the fear circuitry, may contribute to the high prevalence of anxiety, while in attention dysfunctions the default mode and dorsal attention networks displayed diverging activity. These changes suggest that behavioral disorders in DLB are associated with marked impairment in large-scale brain structures and functional connectivity network disruptions. However, many pathobiological mechanisms involved in the development of behavioral disorders in DLB await further elucidation in order to allow an early diagnosis and adequate treatment to prevent progression of these debilitating disorders.

Parkinson disease-associated toxic exposures selectively up-regulate vesicular glutamate transporter vGlut2 in a model of human cortical neurons

Parkinson disease (PD) is the second most common neurodegenerative disease, characterized by both motor and cognitive features. Motor symptoms primarily involve midbrain dopaminergic neurons, while cognitive dysfunction involves cortical neurons. Environmental factors are important contributors to PD risk. In rodents, rare midbrain dopaminergic neurons that coexpress the vesicular glutamate transporter 2 (vGlut2) are resistant to various toxins that induce dopaminergic neurodegeneration. However, it is unclear how, and with what degree of specificity, cortical glutamatergic neurons respond to PD-associated exposures with respect to vGlut2. Here, we found that vGlut2 in stem cell-derived human cortical-like glutamatergic neurons was up-regulated in a highly specific manner to certain PD-related chemicals, such as rotenone, but not others, such as paraquat. Further, exposure to recombinant preformed fibrils of alpha-synuclein (αS), a protein accumulating in PD, also increased vGlut2, while fibrils from non-PD-related proteins did not. This effect did not involve templated aggregation of endogenous αS. Finally, the knockdown of vGlut2 sensitized cortical neurons to rotenone, supporting a functional role in resilience. Thus, up-regulation of vGlut2 occurs in a highly selective manner in response to specific PD-associated exposures in a model of cortical glutamatergic neurons, a key cell type for understanding PD dementia.

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.

Neuropsychological test performance in mild cognitive impairment with Lewy bodies: A systematic review and meta-analysis

BACKGROUND

We sought to characterize the cognitive profile among individuals with mild cognitive impairment with Lewy bodies (MCI-LB) to help guide future clinical criteria.

METHODS

Systematic review and meta-analysis included MCI-LB studies with cognitive data from PubMed, Embase, Web of Science, and PsycINFO (January 1990 to March 2023). MCI-LB scores were compared to controls, MCI due to Alzheimer's disease (MCI-AD), and dementia with Lewy bodies (DLB) groups with random-effects models.

RESULTS

We included 26 studies and 2823 participants. Across all domains, the MCI-LB group performed worse than controls and better than DLB. Compared to MCI-AD, the MCI-LB group performed worse in attention/processing speed (g = -0.24, 95% confidence interval [CI]: -0.35, -0.12), attention/executive (g = -0.42, 95% CI: -0.56, -0.28); better in verbal immediate recall (g = 0.37; 95% CI: 0.15, 0.59) and delayed memory (g = 0.40; 95% CI: 0.22, 0.58).

DISCUSSION

The cognitive profiles in MCI-LB and MCI-AD are consistent with established profiles in DLB and AD. Neuropsychological assessment may be helpful in differential diagnosis, even in early disease states.

HIGHLIGHTS

We performed a systematic review and meta-analysis for cognition in mild cognitive impairment with Lewy bodies (MCI-LB). Compared to MCI due to Alzheimer's disease (MCI-AD), MCI-LB had worse attention, executive function, and processing speed. Compared to MCI-AD, MCI-LB had better verbal immediate and delayed recall. The MCI-LB group was worse on all cognitive domains than controls, and better than dementia with Lewy bodies. Studies used different tests and there is a need for global efforts for harmonization.

Early Changes in the Locus Coeruleus in Mild Cognitive Impairment with Lewy Bodies

BACKGROUND

Although neuromelanin-sensitive magnetic resonance imaging (NM-MRI) has been used to evaluate early neurodegeneration in Parkinson's disease, studies concentrating on the locus coeruleus (LC) in pre-dementia stages of dementia with Lewy bodies (DLB) are lacking.

OBJECTIVES

The aims were to evaluate NM-MRI signal changes in the LC in patients with mild cognitive impairment with Lewy bodies (MCI-LB) compared to healthy controls (HC) and to identify the cognitive correlates of the changes. We also aimed to test the hypothesis of a caudal-rostral α-synuclein pathology spread using NM-MRI of the different LC subparts.

METHODS

A total of 38 MCI-LB patients and 59 HCs underwent clinical and cognitive testing and NM-MRI of the LC. We calculated the contrast ratio of NM-MRI signal (LC-CR) in the whole LC as well as in its caudal, middle, and rostral MRI slices, and we compared the LC-CR values between the MCI-LB and HC groups. Linear regression analyses were performed to assess the relationship between the LC-CR and cognitive outcomes.

RESULTS

The MCI-LB group exhibited a significant reduction in the right LC-CR compared to HCs (P = 0.021). The right LC-CR decrease was associated with impaired visuospatial memory in the MCI-LB group. Only the caudal part of the LC exhibited significant LC-CR decreases in MCI-LB patients compared to HCs on both sides (P < 0.0001).

CONCLUSIONS

This is the first study that focuses on LC-CRs in MCI-LB patients and analyzes the LC subparts, offering new insights into the LC integrity alterations in the initial stages of DLB and their clinical correlates. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Influence of alpha-synuclein on glucose metabolism in Alzheimer's disease continuum: Analyses of α-synuclein seed amplification assay and FDG-PET

INTRODUCTION

We investigated the association between alpha-synuclein (α-syn) pathology and brain glucose metabolism across the cognitive spectrum of Alzheimer's disease (AD) co-pathologies.

METHODS

Fluorodeoxyglucose positron emission tomography (FDG-PET) data from 829 Alzheimer's Disease Neuroimaging Initiative participants (648 cognitively impaired [CI], 181 unimpaired [CU]) were compared between α-syn seed amplification assay (SAA) positive and negative groups. Interactions with cerebrospinal fluid (CSF) AD biomarkers were examined.

RESULTS

SAA+ was associated with widespread hypometabolism among CI individuals, particularly in posterior cortical regions, independent of CSF amyloid and tau levels in the occipital lobes. Regional hypometabolism mediated the effect of α-syn SAA on disease severity in CI individuals, independent of CSF amyloid and tau levels. There were no influences of SAA on FDG-PET in CU individuals.

DISCUSSION

This study supports a model in which α-syn aggregation influences metabolic dysfunction, which then influences clinical disease severity, independent of AD. SAA+ could help optimize participant selection and outcome measures for clinical trials in AD.

HIGHLIGHTS

α-synuclein seed amplification positivity (SAA+) was associated with hypometabolism in cognitively impaired individuals. Hypometabolism mediated the influence of α-synuclein on disease severity. Occipital hypometabolism in SAA+ was independent of cerebrospinal fluid levels of Alzheimer's disease pathology. These findings can optimize future clinical trials targeting α-synuclein pathology.

A systematic review of diffusion tensor imaging and tractography in dementia with Lewy bodies and Parkinson's disease dementia

We reviewed studies using diffusion tensor imaging (DTI) and tractography to characterise white matter changes in Dementia with Lewy Bodies (DLB) and Parkinson's Disease Dementia (PDD). The search included MEDLINE and EMBASE, and we used a narrative strategy to synthesise the evidence. Data was extracted from 57 studies, of which the majority were considered 'good quality'. Subjects with DLB and PDD had widespread white matter changes compared to healthy controls and Parkinson's disease without cognitive impairment, with a relative sparing of the hippocampus. Compared to subjects with Alzheimer's disease (AD), DLB had greater changes in thalamic connectivity and in the nigroputaminal tract, while AD had greater changes in the parahippocampal white matter and fornix. Cognition was associated with widespread white matter changes, visual hallucinations with thalamic and cholinergic connectivity, and parkinsonism with changes in structures involved in motor control. DTI and tractography may therefore be well suited for discriminating DLB and PDD from other types of dementia, and for studying the aetiology of common symptoms.

Acute respiratory failure caused by brainstem demyelinating lesions in an older patient with an atypical relapsing autoimmune disorder

An 84-year-old man presented with somnolence, dysphagia, and right hemiplegia, all occurring within a month, approximately one year after initial admission due to subacute, transient cognitive decline suggestive of acute disseminated encephalomyelitis involving the cerebral white matter. Serial magnetic resonance imaging (MRI) studies over that period revealed three high-intensity signal lesions on fluid-attenuated inversion recovery images, appearing in chronological order in the left upper and left lower medulla oblongata and left pontine base. Despite some clinical improvement following methylprednisolone pulse therapy, the patient died of respiratory failure. Autopsy revealed four fresh, well-defined lesions in the brainstem, three of which corresponded to the lesions detected radiologically. The remaining lesion was located in the dorsal medulla oblongata and involved the right solitary nucleus. This might have appeared at a later disease stage, eventually causing respiratory failure. Histologically, all four lesions showed loss of myelin, preservation of axons, and infiltration of lymphocytes, predominantly CD8-positive T cells, consistent with the histological features of autoimmune demyelinating diseases, particularly the confluent demyelination observed in the early and acute phases of multiple sclerosis (MS). In the cerebral white matter, autoimmune demyelination appeared superimposed on ischemic changes, consistent with the cerebrospinal fluid (CSF) and MRI findings on initial admission. No anti-AQP4 or MOG antibodies or those potentially causing autoimmune encephalitis/demyelination were detected in either the serum or CSF. Despite several similarities to MS, such as the relapsing-remitting disease course and lesion histology, the entire clinicopathological picture in the present patient, especially the advanced age at onset and development of brainstem lesions in close proximity within a short time frame, did not fit those of MS or other autoimmune diseases that are currently established. The present results suggest that exceptionally older individuals can be affected by an as yet unknown inflammatory demyelinating disease of the CNS.