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

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.

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.

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.

Clinical validity and reproducibility of a visual rating scale for cingulate island sign in a real-world memory clinic: An FDG-PET/MRI study

PURPOSE

Brain [18F]FDG-PET is a supportive biomarker for cognitive impairment in Lewy bodies disease (LBD) showing reduced occipital metabolism and presence of the cingulate island sign (CIS), a relative preservation of posterior cingulate cortex (PCC) metabolism compared with precuneus and cuneus. We assess validation, clinical utility, and reproducibility of a qualitative visual CIS scale in the differential diagnosis with Alzheimer's disease (AD) in a memory clinic setting.

METHODS

Sixty-seven patients were studied: 36 LBD, of whom 30 with dementia (DLB) and 6 with mild cognitive impairment (MCI-LB), and 31 AD (20 typical and 11 atypical presentations). They underwent FDG-PET/MRI scans and were followed for at least 24 months. The visual CIS rating scale was scored by a nuclear medicine physician and a neurologist independently. Qualitative CIS scores were validated with ROI-based semiquantitative FDG analysis.

RESULTS

Mean CIS scores were 1.84 ± 1.69 for LBD and 0.9 ± 1.24 for AD (p = 0.001). With a cutoff CIS score ≥2, sensitivity was 0.56, and specificity 0.81 (accuracy 0.67). Positive CIS in patients with AD was due to atypical presentations. Negative CIS in LBD was due to (i) normal FDG-PET in MCI-LB or (ii) marked hypometabolism of both the PCC and cuneus. Visual CIS scores correlated with FDG-uptake (r = 0.45; p < 0.001) and held a high inter-specialists concordance.

DISCUSSION

The visual CIS scale can be successfully scored by different specialists. Lower sensitivity is expected in cases of MCI-LB or dementia due to mixed LBD/AD changes. Specificity may be influenced by the inclusion of atypical AD cases.

PET-Computed Tomography-MR Imaging in Central Nervous System Disorders with Cognitive and Motor Impairment

Neuroimaging, particularly positron emission tomography (PET), plays a crucial role in diagnosing and managing brain disorders by providing insights into diverse neuropathologies such as vascular issues, infections, inflammation, degenerative diseases, and tumors. In dementia, [18F]FDG-PET helps predict Alzheimer's disease (AD) development from mild cognitive impairment, revealing metabolic reductions in specific brain regions. PET's evolution with novel radiotracers and advanced imaging techniques addresses diagnostic challenges and enhances disease monitoring. Despite limitations like off-target binding, PET remains indispensable in clinical neurology, offering noninvasive insights into brain functions, disease progression, and treatment responses.

Recent progress in the applications of presynaptic dopaminergic positron emission tomography imaging in parkinsonism

Nowadays, presynaptic dopaminergic positron emission tomography, which assesses deficiencies in dopamine synthesis, storage, and transport, is widely utilized for early diagnosis and differential diagnosis of parkinsonism. This review provides a comprehensive summary of the latest developments in the application of presynaptic dopaminergic positron emission tomography imaging in disorders that manifest parkinsonism. We conducted a thorough literature search using reputable databases such as PubMed and Web of Science. Selection criteria involved identifying peer-reviewed articles published within the last 5 years, with emphasis on their relevance to clinical applications. The findings from these studies highlight that presynaptic dopaminergic positron emission tomography has demonstrated potential not only in diagnosing and differentiating various Parkinsonian conditions but also in assessing disease severity and predicting prognosis. Moreover, when employed in conjunction with other imaging modalities and advanced analytical methods, presynaptic dopaminergic positron emission tomography has been validated as a reliable in vivo biomarker. This validation extends to screening and exploring potential neuropathological mechanisms associated with dopaminergic depletion. In summary, the insights gained from interpreting these studies are crucial for enhancing the effectiveness of preclinical investigations and clinical trials, ultimately advancing toward the goals of neuroregeneration in parkinsonian disorders.

Upper motor neuron-predominant motor neuron disease presenting as atypical parkinsonism: A clinicopathological study

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by upper and lower motor neuron signs. There are, however, cases where upper motor neurons (UMNs) are predominantly affected, leading to clinical presentations of UMN-dominant ALS or primary lateral sclerosis. Furthermore, cases exhibiting an UMN-predominant pattern of motor neuron disease (MND) presenting with corticobasal syndrome (CBS) have been sparsely reported. This study aims to clarify the clinicopathological features of patients with UMN-predominant MND. We reviewed 24 patients with UMN-predominant MND with TDP-43 pathology in the presence or absence of frontotemporal lobar degeneration. Additionally, we reviewed the medical records of patients with pathologically-confirmed corticobasal degeneration (CBD) who received a final clinical diagnosis of CBS (n = 10) and patients with pathologically-confirmed progressive supranuclear palsy (PSP) who received a final clinical diagnosis of PSP syndrome (n = 10). Of 24 UMN-predominant MND patients, 20 had a clinical diagnosis of an atypical parkinsonian disorder, including CBS (n = 11) and PSP syndrome (n = 8). Only two patients had antemortem diagnoses of motor neuron disease. UMN-predominant MND patients with CBS less frequently exhibited apraxia than those with CBD, and they were less likely to meet clinical criteria for possible or probable CBS. Similarly, UMN-predominant MND patients with PSP syndrome less often met clinical criteria for probable PSP than PSP patients with PSP syndrome. Our findings suggest that UMN-predominant MND can mimic atypical parkinsonism, and should be considered in the differential diagnosis of CBS and PSP syndrome, in particular when criteria are not met.

CD4+ T-cell transcription factors predict phenoconversion in idiopathic rapid eye movement sleep behavior disorder

Aim: Early biomarkers of phenoconversion to neurodegeneration are crucial to identify individuals at high risk. In patients with idiopathic REM sleep behavior disorder (iRBD), the strongest risk factor for neurodegeneration, CD4+ T cells exhibit a peculiar transcription factor pattern.Objective: To assess transcription factor mRNA levels in CD4+ T cells as predictive biomarkers of phenoconversion in iRBD patients.Methods: iRBD patients were followed prospectively. ROC curve analysis and Kaplan-Meier curves were used to assess the discrimination between converters and non-converters.Results: CD4+ T cells from converters had higher STAT1, and lower GATA3 and FOXP3 mRNA levels. Hazard ratio was 58.3 (95% CI: 6.2-547.1) for higher STAT1, 101.2 (95% CI: 16.8-609.4) for lower GATA3 and 15.7 (2.7-91.4) for lower FOXP3.Conclusion: STAT1, GATA3 and FOXP3 mRNA levels in CD4+ T cells are promising predictive biomarkers of phenoconversion in iRBD patients.

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.

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.

Concordance and test-retest consistency of sleep biomarker-based neurodegenerative disorder profiling

Biomarkers that aid in early detection of neurodegeneration are needed to enable early symptomatic treatment and enable identification of people who may benefit from neuroprotective interventions. Increasing evidence suggests that sleep biomarkers may be useful, given the bi-directional relationship between sleep and neurodegeneration and the prominence of sleep disturbances and altered sleep architectural characteristics in several neurodegenerative disorders. This study aimed to demonstrate that sleep can accurately characterize specific neurodegenerative disorders (NDD). A four-class machine-learning algorithm was trained using age and nine sleep biomarkers from patients with clinically-diagnosed manifest and prodromal NDDs, including Alzheimer's disease dementia (AD = 27), Lewy body dementia (LBD = 18), and isolated REM sleep behavior disorder (iRBD = 15), as well as a control group (CG = 58). The algorithm was validated in a total of 381 recordings, which included the training data set plus an additional AD = 10, iRBD = 18, Parkinson disease without dementia (PD = 29), mild cognitive impairment (MCI = 78) and CG = 128. Test-retest consistency was then assessed in LBD = 10, AD = 9, and CG = 46. The agreement between the NDD profiles and their respective clinical diagnoses exceeded 75% for the AD, LBD, and CG, and improved when NDD participants classified Likely Normal with NDD indications consistent with their clinical diagnosis were considered. Profiles for iRBD, PD and MCI participants were consistent with the heterogeneity of disease severities, with the majority of overt disagreements explained by normal sleep characterization in 27% of iRBD, 21% of PD, and 26% of MCI participants. For test-retest assignments, the same or similar NDD profiles were obtained for 88% of LBD, 86% in AD, and 98% of CG participants. The potential utility for NDD subtyping based on sleep biomarkers demonstrates promise and requires further prospective development and validation in larger NDD cohorts.

The Alzheimer's Association clinical practice guideline for the Diagnostic Evaluation, Testing, Counseling, and Disclosure of Suspected Alzheimer's Disease and Related Disorders (DETeCD-ADRD): Executive summary of recommendations for specialty care

US clinical practice guidelines for the diagnostic evaluation of cognitive impairment due to Alzheimer's disease (AD) or a related dementia (ADRD) are two decades old. This evidence-based guideline was developed to empower all clinicians to implement a structured approach for evaluating a patient with symptoms that may represent clinical AD/ADRD. An expert workgroup conducted a review of 7374 publications (133 met inclusion criteria) and developed recommendations as steps in an evaluation process. This summary briefly reviews core recommendations and details specialist recommendations of a high-quality, evidence-supported evaluation process aimed at characterizing, diagnosing, and disclosing the patient's cognitive functional status, cognitive-behavioral syndrome, and likely underlying brain disease so that optimal care plans to maximize patient/care partner dyad quality of life can be developed; a companion article summarizes primary care recommendations. If clinicians use the recommendations in this guideline and health-care systems provide adequate resources, outcomes should improve in most patients in most practice settings. HIGHLIGHTS: US clinical practice guidelines for the diagnostic evaluation of cognitive impairment due to Alzheimer's disease (AD) or related dementias (ADRD) are decades old and aimed at specialists. This evidence-based guideline was developed to empower all-including primary care-clinicians to implement a structured approach for evaluating a patient with symptoms that may represent clinical AD/ADRD. This summary focuses on recommendations appropriate for specialty practice settings, forming key elements of a high-quality, evidence-supported evaluation process aimed at characterizing, diagnosing, and disclosing the patient's cognitive functional status, cognitive-behavioral syndrome, and likely underlying brain disease so that optimal care plans to maximize patient/care partner dyad quality of life can be developed; a companion article summarizes primary care recommendations. If clinicians use this guideline and health-care systems provide adequate resources, outcomes should improve in most patients in most practice settings.

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

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. Single-photon emission computed tomography ethyl cysteinate dimer imaging was performed on each patient, and relative tracer uptake levels across 47 regions of interest and 240 subregions were analyzed. 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 greatest difference in perfusion was in the visual cortices, with lower mean perfusion observed in PDD patients than those with DLB. However, no comparisons remained significant at the 0.05 significance level after adjusting for multiple comparisons with the Benjamini-Hochberg procedure.

Proteomic signatures of Alzheimer's disease and Lewy body dementias: A comparative analysis

INTRODUCTION

We aimed to identify unique proteomic signatures of Alzheimer's disease (AD), dementia with Lewy bodies (DLB), and Parkinson's disease dementia (PDD).

METHODS

We conducted a comparative proteomic analysis of 33 post mortem brains from AD, DLB, and PDD individuals without dementia focusing on prefrontal, cingulate, and parietal cortices, using weighted gene co-expression network analyses with differential enrichment analysis.

RESULTS

Network modules revealed hub proteins common to all dementias. Lewy body dementias differed from AD by reduced levels of the autophagy protein p62 (SQSTM1), whereas DLB was distinguished from both AD and PDD by altered TRIM33 and cysteine/glutamate transporter (SLC7A11) across brain regions. An increase in mitochondrial and synaptic proteins was related to better cognition whereas enrichment in the extracellular matrix, complement system, and autophagy proteins was associated with greater cognitive impairment.

DISCUSSION

Our study offers valuable insights into the network-based biomarker characterization of molecular signatures of AD, DLB, and PDD.

HIGHLIGHTS

Reduced levels of the autophagy protein p62 (SQSTM1) differentiated Lewy body dementias from Alzheimer's disease (AD) across multiple brain regions. Dementia with Lewy bodies (DLB) was distinguished from both AD and Parkinson's disease dementia (PDD) by altered TRIM33 and cysteine/glutamate transporter (SLC7A11) levels across brain regions. Key mitochondrial oxidative phosphorylation proteins (e.g., COX7A2, TOMM40L, NDUFV1), and synaptic proteins (e.g., GABRB3, GABRB2, GLUA3, GLUA4, SNAP47, dynamin1) were more abundant in preserved cognitive states. Extracellular matrix proteins and members of the complement system (decorin, biglycan, C4A, C4B) showed a strong positive correlation with cognitive decline.

Alzheimer's Association clinical practice guideline for the Diagnostic Evaluation, Testing, Counseling, and Disclosure of Suspected Alzheimer's Disease and Related Disorders (DETeCD-ADRD): Executive summary of recommendations for primary care

US clinical practice guidelines for the diagnostic evaluation of cognitive impairment due to Alzheimer's disease (AD) or AD and related dementias (ADRD) are decades old and aimed at specialists. This evidence-based guideline was developed to empower all-including primary care-clinicians to implement a structured approach for evaluating a patient with symptoms that may represent clinical AD/ADRD. Through a modified-Delphi approach and guideline-development process (7374 publications were reviewed; 133 met inclusion criteria) an expert workgroup developed recommendations as steps in a patient-centered evaluation process. This summary focuses on recommendations, appropriate for any practice setting, forming core elements of a high-quality, evidence-supported evaluation process aimed at characterizing, diagnosing, and disclosing the patient's cognitive functional status, cognitive-behavioral syndrome, and likely underlying brain disease so that optimal care plans to maximize patient/care partner dyad quality of life can be developed; a companion article summarizes specialist recommendations. If clinicians use this guideline and health-care systems provide adequate resources, outcomes should improve in most patients in most practice settings. Highlights US clinical practice guidelines for the diagnostic evaluation of cognitive impairment due to Alzheimer's disease (AD) or AD and related dementias (ADRD) are decades old and aimed at specialists. This evidence-based guideline was developed to empower all-including primary care-clinicians to implement a structured approach for evaluating a patient with symptoms that may represent clinical AD/ADRD. This summary focuses on recommendations, appropriate for any practice setting, forming core elements of a high-quality, evidence-supported evaluation process aimed at characterizing, diagnosing, and disclosing the patient's cognitive functional status, cognitive-behavioral syndrome, and likely underlying brain disease so that optimal care plans to maximize patient/care partner dyad quality of life can be developed; a companion article summarizes specialist recommendations. If clinicians use this guideline and health-care systems provide adequate resources, outcomes should improve in most patients in most practice settings.

Cognitive decline profiles associated with lewy pathology in the context of Alzheimer's disease neuropathologic change

BACKGROUND

Alzheimer's disease neuropathologic change (ADNC) and Lewy pathology (LP) often coexist in cognitively impaired individuals. These pathologies' relative distribution and severity may modify these individuals' clinical presentation, cognitive profile, and prognosis. Therefore, we examined the contributions of LP and concomitant ADNC to disease survival and profiles of cognitive decline in preclinical and clinical stages in a large neuropathologically diagnosed group.

METHODS

We evaluated 597 participants with LP and 491 participants with intermediate/high ADNC in the absence of LP from the National Alzheimer Coordinating Center (NACC) database. At baseline, 237 participants were cognitively normal (CN), 255 were diagnosed with mild cognitive impairment (MCI), and 596 with dementia. Cognition was assessed using three cognitive domain scores (i.e., Memory, Executive, and Language) from the NACC Uniform Dataset (UDS) neuropsychological test battery, MMSE, and Clinical Dementia Rating (CDR). Multivariate adaptive regression splines were used to evaluate associations between baseline cognitive scores and mean annual rate of change over two years. The likelihood of progression to MCI or dementia was assessed using Cox hazard models.

RESULTS

Neocortical LP, independent of the clinical diagnosis, was associated with lower Executive and higher Language and Memory scores at baseline, whereas Braak V-VI neurofibrillary tangle pathology was associated with lower Memory and Language scores. Similarly, neocortical LP was associated with faster Executive decline, whereas Braak V-VI neurofibrillary tangle pathology was associated with faster Memory and Language decline. A clinical diagnosis of Lewy Body Dementia (i.e., a strong LP phenotype) was associated with the LP cognitive profile and shorter disease duration. Progression to incident MCI or dementia was primarily associated with the degree of tau pathology; neocortical LP or a diagnosis of Lewy Body Dementia only predicted progression when those with intermediate/high ADNC were excluded.

CONCLUSIONS

LP and ADNC differentially affected cross-sectional and longitudinal cognitive profiles in a large autopsy sample. Concomitant Braak V-VI neurofibrillary tangle pathology had a strong impact on clinical progression in those with LP, regardless of the initial stage. Thus, LB and ADNC co-pathology interact to affect cognitive domains that may be used to track Lewy Body disease longitudinally and as outcome measures in therapeutic trials.

Is the Swallow Tail Sign a Useful Imaging Biomarker in Clinical Neurology? A Systematic Review

BACKGROUND

Loss of dorsolateral nigral hyperintensity (DNH) in iron-sensitive sequences of Magnetic Resonance Imaging (MRI), also described as "swallow tail sign" (STS) loss, has shown promising diagnostic value in Parkinson's Disease (PD) and Atypical Parkinsonian Syndromes (APS).

OBJECTIVE

To conduct a bibliometric analysis on substantia nigra MRI and a systematic review on the clinical utility of STS visual assessment on Susceptibility-Weighted Imaging in various clinical entities.

METHODS

VOSviewer's keyword co-occurrence network was employed using Web of Science (WOS). Complying with the PRISMA statement, we searched MEDLINE, WOS, SCOPUS, ProQuest and Google Scholar for peer-reviewed studies conducted in vivo, excluding quantitative imaging techniques.

RESULTS

DNH is a relatively novel parameter in substantia nigra MRI literature. Our SWI-focused review included 42 studies (3281 patients). Diagnostic accuracy of STS loss for PD/APS differentiation from controls and for Lewy Body Dementia differentiation from other dementias was 47.8-98.5% and 76-90%, respectively, with poorer capacity, however, in delineating PD from APS. STS evaluation in idiopathic REM sleep behavior disorder, a sign of prodromal PD, was typically concordant with nuclear scans, identifying subjects with high conversion risk. Iron deposition can affect STS in Multiple Sclerosis and STS loss in Amyotrophic Lateral Sclerosis is linked with multisystem degeneration, with poorer prognosis. In healthy individuals iron-induced microvessel changes are suspected for false positive results.

CONCLUSION

STS assessment exhibits potential in different settings, with a possibly intermediate role in the diagnostic work-up of various conditions. Its clinical utility should be explored further, through standardized MRI protocols on larger cohorts.

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.

Cuneus atrophy and Parkinsonian phenoconversion in cognitively unimpaired patients with isolated REM sleep behavior disorder

Isolated rapid-eye-movement sleep behavior disorder (iRBD) is a strong predictor of Parkinson's disease and Dementia with Lewy bodies. Previous studies indicate that cortical atrophy in iRBD patients may be linked to cognitive impairment, but the pattern of atrophy is inconsistently reported. This study aimed to elucidate cortical atrophy patterns in a cognitively unimpaired iRBD cohort, focusing on regions associated with cognitive functions, particularly the cuneus/precuneus, and evaluated the predictive value for future phenoconversion. We conducted voxel-based morphometry and region of interest (ROI) analysis of structural MRI scans of 36 healthy controls and 19 iRBD patients, nine of whom also received a 3-year follow-up MRI scan. The iRBD patients were followed clinically for 8 years, and time-to-event analyses, using Cox regression, were performed based on baseline ROI volumes. The iRBD patients had lower gray-matter volume in the cuneus/precuneus region as well as in subcortical structures (caudate nuclei and putamen) compared to controls. Eight iRBD patients developed either Parkinson's disease (N = 4) or Dementia with Lewy bodies (N = 4) during the follow-up period. Time-to-event analyses showed that lower right cuneus volume was associated with a higher risk of phenoconversion to alpha-synuclein-linked Parkinsonism in the iRBD patients (Hazard ratio = 13.0, CI: 1.53-110), and correlated with shorter time to conversion. In addition, lower volumes of the bilateral precuneus trended to indicate a higher risk of phenoconversion. These findings suggest a potential predictive value of cuneus and precuneus volumes in identifying iRBD patients at risk of disease progression, even before the onset of cognitive impairment.

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.

Disentangling relationships between Alzheimer's disease plasma biomarkers and established biomarkers in patients of tertiary memory clinics

BACKGROUND

Several plasma biomarkers for Alzheimer's disease (AD) have demonstrated diagnostic and analytical robustness. Yet, contradictory results have been obtained regarding their association with standard diagnostic markers of AD. This study aims to investigate the specific relationship between the AD biomarkers currently used in clinical practice and the plasma biomarkers.

METHODS

In a memory clinic cohort, we analysed plasma pTau181, pTau217, pTau231, respectively, GFAP, NfL, CSF pTau181, Aβ-PET scans, and MRI/CT visual read of atrophy. We utilized methods based on multiple linear regression to evaluate the specific associations between clinically used and recently developed plasma biomarkers, while also considering demographic variables such as age and sex.

FINDINGS

Although plasma pTau181, pTau217, pTau231, and GFAP were significantly associated with both Aβ-PET and CSF pTau181, Aβ-PET explained more variance in the levels of these biomarkers. The effect of CSF pTau181 on plasma GFAP and pTau181 was completely attenuated by Aβ-PET, whereas pTau231 and pTau217 were affected by both Aβ-PET and CSF pTau181 levels. Unlike these biomarkers, increased NfL was rather indicative of brain atrophy and older age. Based on the effect sizes, plasma pTau217 emerged as highly effective in distinguishing between A+ and A-, and T+ and T- individuals, with 60% of variance in plasma pTau217 explained by clinical AD biomarkers.

INTERPRETATION

Amyloid burden primarily drives the changes in plasma pTau181, pTau217, pTau231, and GFAP. In contrast to plasma pTau217, a significant portion of variance in plasma pTau181, pTau231, GFAP, NfL remains unexplained by clinical AD biomarkers.

FUNDING

This research is supported by the Swedish Research Council VR: 2017-06086, 2020-4-3018, 2024-2027; Swedish Brain Foundation, Swedish Alzhzeimer Foundation, CIMED Region Stockholm/Karolinska Institutet; the Region Stockholm - Karolinska Institutet regional agreement on medical training and clinical research (ALF), Fondation Recherche sur Alzheimer (France).

Subject-Level Segmentation Precision Weights for Volumetric Studies Involving Label Fusion

In neuroimaging research, volumetric data contribute valuable information for understanding brain changes during both healthy aging and pathological processes. Extracting these measures from images requires segmenting the regions of interest (ROIs), and many popular methods accomplish this by fusing labels from multiple expert-segmented images called atlases. However, post-segmentation, current practices typically treat each subject's measurement equally without incorporating any information about variation in their segmentation precision. This naïve approach hinders comparing ROI volumes between different samples to identify associations between tissue volume and disease or phenotype. We propose a novel method that estimates the variance of the measured ROI volume for each subject due to the multi-atlas segmentation procedure. We demonstrate in real data that weighting by these estimates markedly improves the power to detect a mean difference in hippocampal volume between controls and subjects with mild cognitive impairment or Alzheimer's disease.

REM sleep behavior disorder and Prodromal Parkinson's Disease in patients with Essential Tremor

Several studies suggested the presence of non-motor symptoms in Essential Tremor (ET), including REM sleep behavioral disorder (RBD). RBD is an essential criterion for Prodromal Parkinson's Disease (PPD), suggesting a link between ET and PD. Our objective was to assess the prevalence and features of ET patients with RBD and PDD. RBD was diagnosed by questionnaire screening, followed by polysomnography. PPD risk factors and prodromic markers were assessed with a structured protocol. Patients were characterized regarding tremor features. ET patients with RBD (ET-RBD) and PPD (ET-PPD) were compared to patients without RBD (ET-nonRBD) and without PPD (ET-nonPPD), respectively. ET-RBD patients were also compared with a group of isolated RBD (iRBD) regarding PPD features. We assessed a total of 64 ET patients. Five (8.3 %) and 4 (6.3 %) had criteria for RBD and PPD, respectively. ET-RBD patients did not differ from ET-nonRBD except for a higher prevalence of PPD. There were no significant differences between ET-RBD and iRBD (n = 12) groups. ET-PPD had a higher prevalence of positive DaT-Scans and RBD compared to ET-nonPPD. Three ET-RBD patients had PPD and 3 ET-PPD had RBD. Both RBD and PPD are more frequent in ET patients than in general aged population but not related with specific tremor features. ET-RBD patients did not differ significantly from iRBD patients, a group prone to develop PD. These data suggest a link between ET and PD and are in accordance with studies showing an increase incidence of lewy-body pathology and PD in ET populations.

Utility of Tau PET in the diagnostic work up of neurodegenerative dementia among Indian patients

BACKGROUND AND OBJECTIVES

Tau PET is being increasingly appraised as a novel diagnostic modality for dementia work up. Given limited data among South Asians, we assessed the frequency, patterns, phenotypic associations and incremental value of positive Tau PET scans in clinically diagnosed neurodegenerative dementia.

METHODS

This cross-sectional study recruited consecutive patients of Alzheimer's disease (AD) and non-AD syndromes (September 2021 to October 2022, India). Participants underwent clinical interview, cognitive assessment, MRI brain and tau PET scan ([F-18]ML-104). Visual read in a priori regions of interest was used to identify patterns of tau deposition in the brain.

RESULTS

We recruited 54 participants (mean age: 63.2 ± 9.2 years, 64.8 % men, 77.8 % dementia, 70.4 % early onset cases, 37.8 % APOE4+). The analysis identified abnormal tau uptake in 40/54 (74.1 %) participants; with uptake in AD signature areas in 27/40 (67.5 %) cases [cortical subtype (74.1 %), limbic (14.8 %), combined cortical/limbic (11.1 %)], and patterns not conforming to AD in 13/40 (32.5 %) cases. Tau PET substantiated the diagnosis of AD among 17/19 (89.5 %) cases with clinically diagnosed AD dementia, 8/23 (34.8 %) cases with suspected non-AD cause, and 2/12 (16.7 %) cases with mild cognitive impairment. A trend for increasing proportion of early onset cases, and worsening cognition, behavior and functional ability was seen, from 'limbic' to 'combined cortical/limbic' to 'cortical' subgroups.

CONCLUSION

Tau PET is a useful modality to differentiate AD dementia from other neurodegenerative causes in the Indian setting where amyloid biomarkers are not widely available. Biological subtypes of AD map well onto clinical phenotypes and need study in larger cohorts.

Investigating the potential of novel thiazole derivatives in treating Alzheimer's and Parkinson's diseases

The study aimed to investigate 12 novel thiazole compounds in the treatment of neurodegenerative disorders. The compounds produced were evaluated for their inhibitory efficacy against acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and monoamine oxidases (MAOs). Among the compounds, 5d, 5e, and 5j showed the highest AChE inhibitory activity. The IC50 values for compounds are 0.223 ± 0.010 µM, 0.092 ± 0.003 µM, and 0.054 ± 0.002 µM, respectively. In addition, molecular docking analyses and molecular dynamic simulation were used to examine the interactions of these compounds with protein sites. The results suggest that thiazole-ring compounds could serve as a promising basis for the development of drugs aimed at treating neurodegenerative diseases (NDD), caused by Parkinson's and Alzheimer's diseases.

What is the future for dementia with Lewy bodies?

Dementia with Lewy bodies (DLB) is the second most common neurodegenerative dementia after Alzheimer's disease (AD), yet it remains under-recognized and frequently misdiagnosed due to heterogenous clinical presentations, the presence of co-pathology, and the lack of specific diagnostic tools. Pathologically, DLB is characterized by the accumulation of misfolded alpha-synuclein (aSyn) aggregates, known as Lewy bodies. Recent advancements have improved in vivo detection of aSyn pathology through techniques such as seed amplification assays, monoclonal antibodies, and positron emission tomography using novel small-molecule ligands. The ability to detect aSyn in vivo has sparked dialogue about using biomarkers to identify individuals with aSyn, similar to the approach influencing the field of AD. Proponents argue that biological staging could facilitate the detection of preclinical disease stages, allowing for earlier intervention and targets for disease modification, and could improve diagnostic sensitivity and accuracy in selecting patients for clinical trials. However, critics caution that this method may oversimplify the complexity of DLB and overlook its clinical heterogeneity, also highlighting practical challenges related to implementation, cost, and global access to advanced diagnostic technologies. Importantly, although significant progress has been made in detecting aSyn for diagnostic purposes, disease-modifying therapies targeting aSyn have yet to demonstrate clear efficacy in slowing disease progression. Elucidating the physiological and pathophysiological roles of aSyn remains an urgent priority in neurodegenerative research. Other experimental research priorities for DLB include developing improved cellular and animal models that reflect epigenetic and environmental factors, mapping post-translational modifications, and systematically characterizing neurons that are vulnerable and resistant to lewy pathology using a multi-omic approach. Clinically, there is an urgent need for international, prospective, longitudinal studies and for validated, disease-specific outcome measures. Addressing these priorities is essential for advancing our understanding of DLB and developing effective therapies.

Myelin basic protein and TREM2 quantification in the CSF of patients with Multiple System Atrophy and other Parkinsonian conditions

BACKGROUND

It is well known that myelin disruption and neuroinflammation are early and distinct pathological hallmarks in multiple system atrophy (MSA) as well as in idiopathic Parkinson's disease and in other atypical Parkinsonian syndromes. The objective of this study was to assess the value of non-neuronal biomarker candidates that reflect myelin disruption and neuroinflammation.

METHODS

Myelin basic protein (MBP) and the soluble form of TREM2 were quantified in a comprehensive movement disorder cohort from two different neurological centers, comprising a total of 171 CSF samples. Commercially available ELISA systems were employed for quantification.

RESULTS

The results of the MBP analysis revealed a significant increase in cerebrospinal fluid (CSF) MBP levels in all atypical Parkinsonian conditions compared to PD. This differentiation was more pronounced in the MSA-c subtype compared to MSA-p. Receiver operating characteristic (ROC) analysis revealed a significant discrimination between PD and MSA (p = 0.032, AUC = 0.70), PD and DLB (p = 0.006, AUC = 0.79) and PD and tauopathies (p = 0.006, AUC = 0.74). The results of the TREM2 analysis demonstrated no significant differences between the PD and atypical Parkinsonian groups if not adjusted for confounders. After adjusting for age, sex, and disease duration, the PD group exhibited significantly higher TREM2 levels compared to the DLB group (p = 0.002).

CONCLUSIONS

In conclusion, MBP, but not TREM2, is elevated in the CSF of not only MSA but in all atypical Parkinsonian conditions compared to idiopathic Parkinson's disease. This highlights the value of the evaluation of myelin/oligodendrocyte-associated markers in neurodegenerative movement disorders.

Neuroanatomical and clinical correlates of prodromal dementia with Lewy bodies: a systematic literature review of neuroimaging findings

Prodromal Dementia with Lewy bodies (pro-DLB) has been recently defined; however, the neuroanatomical and functional correlates of this stage have not yet been univocally established. This study aimed to systematically review neuroimaging findings focused on pro-DLB. A literature search of works employing MRI, PET, and SPECT was performed. Forty records were included: 15 studies assessed gray matter (GM) and white matter (WM) integrity, and 31 investigated metabolism, perfusion, and resting-state connectivity. Results showed that, in pro-DLB, frontal lobe areas were characterized by decreased function, cortical atrophy, and WM damage. Volumetric reductions were found in the insula, which also showed heightened metabolism. A pattern of hypofunction and structural damage was observed in the lateral and ventral temporal lobe; instead, the parahippocampal cortex and hippocampus exhibited greater function. Hypofunction marked parietal and occipital regions, with additional atrophy in the medial occipital lobe and posterior parietal cortex. Subcortically, atrophy and microstructural damage in the nucleus basalis of Meynert were reported, and dopamine transporter uptake was reduced in the basal ganglia. Overall, structural and functional damage was already present in pro-DLB and was coherent with the possible clinical onset. Frontal and parieto-occipital alterations may be associated with deficits in attention and executive functions and in visuo-perceptual/visuo-spatial abilities, respectively. Degeneration of cholinergic and dopaminergic transmission appeared substantial at this disease stage. This review provided an updated and more precise depiction of the brain alterations that are specific to pro-DLB and valuable to its differentiation from physiological aging and other dementias.

Electroencephalogram rhythmic and arrhythmic spectral components and functional connectivity at resting state may predict the development of synucleinopathies in idiopathic rapid eye movement sleep behavior disorder

STUDY OBJECTIVES

Idiopathic/isolated rapid eye movement-sleep behavior disorder (iRBD) often precedes the onset of synucleinopathies. Here, we investigated whether baseline resting-state EEG advanced spectral power and functional connectivity differed between iRBD patients who converted towards a synucleinopathy at follow-up and those who did not.

METHODS

Eighty-one participants with iRBD (66.89 ± 6.91 years) underwent a baseline resting-state EEG recording, a neuropsychological assessment, and a neurological examination. We estimated EEG power spectral density using standard analyses and derived spectral estimates of rhythmic and arrhythmic components. Global and pairwise EEG functional connectivity analyses were computed using the weighted phase-lag index (wPLI). Pixel-based permutation tests were used to compare groups.

RESULTS

After a mean follow-up of 5.01 ± 2.76 years, 34 patients were diagnosed with a synucleinopathy (67.81 ± 7.34 years) and 47 remained disease-free (65.53 ± 7.09 years). Among patients who converted, 22 were diagnosed with Parkinson's disease and 12 with dementia with Lewy bodies. As compared to patients who did not convert, patients who converted exhibited at baseline higher relative theta standard power, steeper slopes of the arrhythmic component and higher theta rhythmic power mostly in occipital regions. Furthermore, patients who converted showed higher beta global wPLI but lower alpha wPLI between left temporal and occipital regions.

CONCLUSIONS

Analyses of resting-state EEG rhythmic and arrhythmic components and functional connectivity suggest an imbalanced excitatory-to-inhibitory activity within large-scale networks, which is associated with later development of a synucleinopathy in patients with iRBD.

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.

Impact of Lewy bodies disease on visual skills and memory abilities: from prodromal stages to dementia

Dementia with Lewy bodies (DLB) and its prodromal presentation with mild cognitive impairment is characterized by prominent deficits in attention/executive domains and in visual processing abilities with relative sparing of memory. Neuropsychological research is continuously refining the tools to define more in detail the patterns of relatively preserved and impaired cognitive abilities that help differential diagnosis between DLB and Alzheimer disease (AD). This review summarizes the main studies exploring specific cognitive tasks investigating different visual processing abilities and verbal memory that better differentiate DLB from AD. The findings provide evidence that substantial impairments in visual-spatial and visual-constructional abilities and relatively better performance on memory tasks that depend on hippocampal function characterize the prodromal stage of DLB. The ability to detect early indicators of prodromal DLB through clinical and cognitive assessments is the first step to guide instrumental diagnostic work-ups and provide the opportunity for early intervention.

Behavioral variant frontotemporal dementia with pathogenic variant in MAPT presenting as dementia with Lewy body disease

A 75-year-old Chinese American man presented to behavioral neurology clinic for a second opinion of dementia with Lewy body disease (DLB). The clinical manifestations met the criteria for a probable DLB diagnosis. Yet, in-depth evaluation unveiled clinical history, family history, and neuroimaging evidences that suggested a diagnosis of behavioral variant frontotemporal dementia (FTD). A heterozygous pathogenic variant in the microtubule-associated protein Tau (MAPT) was identified through genetic testing and confirmed the diagnosis of autosomal dominant MAPT-related FTD. This case is the first reported instance of MAPT-related FTD presenting with well-formed visual hallucinations in an elderly Chinese American.

Atypical Parkinsonian Syndromes: Structural, Functional, and Molecular Imaging Features

Atypical parkinsonian syndromes, also known as Parkinson-plus syndromes, are a heterogeneous group of movement disorders, including dementia with Lewy bodies (DLB), progressive supranuclear palsy (PSP), multisystem atrophy (MSA), and corticobasal degeneration (CBD). This review highlights the characteristic structural, functional, and molecular imaging features of these complex disorders. DLB typically demonstrates parieto-occipital hypometabolism with involvement of the cuneus on FDG-PET, whereas dopaminergic imaging, such as [123I]-FP-CIT SPECT (DaTscan) or fluorodopa (FDOPA)-PET, can be utilized as an adjunct for diagnosis. PSP typically shows midbrain atrophy on structural imaging, whereas FDG-PET may be useful to depict frontal lobe hypometabolism and tau-PET confirms underlying tauopathy. MSA typically demonstrates putaminal or cerebellar atrophy, whereas FDG-PET highlights characteristic nigrostriatal or olivopontocerebellar hypometabolism, respectively. Finally, CBD typically shows asymmetric atrophy in the superior parietal lobules and corpus callosum, whereas FDG and tau-PET demonstrate asymmetric hemispheric and subcortical involvement contralateral to the side of clinical deficits. Additional advanced neuroimaging modalities and techniques described may assist in the diagnostic work-up or are promising areas of emerging research.

Posterior hippocampal sparing in Lewy body disorders with Alzheimer's copathology: An in vivo MRI study

BACKGROUND

Lewy body disorders (LBD), encompassing Parkinson disease (PD), PD dementia (PDD), and dementia with Lewy bodies (DLB), are characterized by alpha-synuclein pathology but often are accompanied by Alzheimer's disease (AD) neuropathological change (ADNC). The medial temporal lobe (MTL) is a primary locus of tau accumulation and associated neurodegeneration in AD. However, it is unclear the extent to which AD copathology in LBD (LBD/AD+) contributes to MTL-specific patterns of degeneration. We employ a MTL subregional segmentation strategy of T1-weighted (T1w) MRI in biomarker-supported or autopsy-confirmed LBD and LBD/AD+ to investigate the anatomic consequences of co-occurring LBD/AD+ pathology on neurodegeneration.

METHODS

We studied 167 individuals with clinical diagnoses of LBD (PD, n = 124 (74.3 %); PDD, n = 11 (6.6 %); DLB, n = 32 (19.2 %)) with available T1w MRI and AD biomarkers or autopsy evidence of ADNC. Individuals were further biologically classified as LBD/AD+ based on hierarchical evidence of ADNC pathology: 1) AD "intermediate" or "high" by ABC neuropathologic criteria (n = 39 (23.4 %)); 2) positive amyloid PET (n = 2 (1.2 %)); or 3) CSF β-amyloid1-42 < 185.7 pg/mL n = 126 (75.4 %)). The T1 Automated Segmentation of Hippocampal Subfields (ASHS) pipeline was used to compute volume and thickness measurements of MTL subregions in LBD/AD- and LBD/AD+. Linear regression tested the association of AD copathology and subregion volume/thickness, covarying for age and sex, and intracranial volume for volume measurements. Secondary analyses correlated MTL subregional volume/thickness with cognition and neuropathology.

RESULTS

LBD/AD+ had decreased volume/thickness compared to LBD/AD- in all MTL subregions except posterior hippocampus. The greatest effect sizes were seen in Brodmann Area 35 (BA35) (Cohen's d = 0.62, p = 0.002, β = 0.107 ± 0.034), and entorhinal cortex (ERC) (Cohen's d = 0.56, p = 0.006, β = 0.088 ± 0.031). Smaller differences were seen in the parahippocampal cortex (PHC) (Cohen's d = 0.5, p = 0.012, β = 0.082 ± 0.033), BA36 (Cohen's d = 0.47, p = 0.021, β = 0.090 ± 0.039) and anterior hippocampus (Cohen's d = 0.45, p = 0.029, β = 111.790 ± 50.595). Verbal memory scores positively correlated with volume/thickness in anterior and posterior hippocampus, BA35, ERC and PHC, while visuospatial memory positively correlated only in BA35. In the subset of participants with autopsy, lower ERC volume was associated with a higher tau load in ERC (adjusted odds ratio 0.013, 95 % CI [0.0002, 0.841], uncorrected p = 0.041).

CONCLUSIONS

Relative to LBD/AD-, LBD/AD+ has greater T1w MRI evidence of atrophy in multiple MTL subregions. Atrophy in MTL subregions associates with memory performance and tau pathological load. The observed pattern of atrophy largely follows expectation from AD Braak stages, except for posterior hippocampus. Longitudinal studies are needed to validate the hypothesized spread of neurodegeneration.

Longitudinal changes in cardiac mIBG scintigraphy in mild cognitive impairment with Lewy bodies

The aim of this study was to determine whether there was a significant change in cardiac [123I]-metaiodobenzylguanidine uptake between baseline and follow-up in individuals with mild cognitive impairment with Lewy bodies (MCI-LB) who had normal baseline scans. Eight participants with a diagnosis of probable MCI-LB and a normal baseline scan consented to a follow-up scan between 2 and 4 years after baseline. All eight repeat scans remained normal; however, in three cases uptake decreased by more than 10%. The mean change in uptake between baseline and repeat was -5.2% (range: -23.8% to +7.0%). The interpolated mean annual change in uptake was -1.6%.

Autoantibody profiles in Alzheimer´s, Parkinson´s, and dementia with Lewy bodies: altered IgG affinity and IgG/IgM/IgA responses to alpha-synuclein, amyloid-beta, and tau in disease-specific pathological patterns

BACKGROUND

Alzheimer's disease (AD) and Parkinson's disease (PD) are leading neurodegenerative disorders marked by protein aggregation, with AD featuring amyloid-beta (Aβ) and tau proteins, and PD alpha-synuclein (αSyn). Dementia with Lewy bodies (DLB) often presents with a mix of these pathologies. This study explores naturally occurring autoantibodies (nAbs), including Immunoglobulin (Ig)G, IgM, and IgA, which target αSyn, Aβ and tau to maintain homeostasis and were previously found altered in AD and PD patients, among others.

MAIN TEXT

We extended this investigation across AD, PD and DLB patients investigating both the affinities of IgGs and levels of IgGs, IgMs and IgAs towards αSyn, Aβ and tau utilizing chemiluminescence assays. We confirmed that AD and PD patients exhibited lower levels of high-affinity anti-Aβ and anti-αSyn IgGs, respectively, than healthy controls. AD patients also showed diminished levels of high-affinity anti-αSyn IgGs, while anti-tau IgG affinities did not differ significantly across groups. However, DLB patients exhibited increased anti-αSyn IgG but decreased anti-αSyn IgM levels compared to controls and PD patients, with AD patients showing a similar pattern. Interestingly, AD patients had higher anti-Aβ IgG but lower anti-Aβ IgA levels than DLB patients. DLB patients had reduced anti-Aβ IgM levels compared to controls, and anti-tau IgG levels were lower in AD than PD patients, who had reduced anti-tau IgM levels compared to controls. AD patients uniquely showed higher anti-tau IgA levels. Significant correlations were observed between clinical measures and nAbs, with negative correlations between anti-αSyn IgG affinity and levels in DLB patients and a positive correlation with anti-αSyn IgA levels in PD patients. Disease-specific changes in nAb levels and affinity correlations were identified, highlighting altered immune responses.

CONCLUSION

This study reveals distinctive nAb profiles in AD, DLB, and PD, pinpointing specific immune deficiencies against pathological proteins. These insights into the autoreactive immune system's role in neurodegeneration suggest nAbs as potential markers for vulnerability to protein aggregation, offering new avenues for understanding and possibly diagnosing these conditions.

Gba1 E326K renders motor and non-motor symptoms with pathological α-synuclein, tau and glial activation

Mutations in the GBA1 gene are common genetic risk factors for Parkinson's disease, disrupting enzymatic activity and causing lysosomal dysfunction, leading to elevated α-synuclein levels. Although the role of GBA1 in synucleinopathy is well established, recent research underscores neuroinflammation as a significant pathogenic mechanism in GBA1 deficiency. This study investigates neuroinflammation in Gba1 E326K knock-in mice, a model associated with increased risk of Parkinson's disease and dementia. At 9 and 24 months, we assessed GBA1 protein and activity, α-synuclein pathology, neurodegeneration, motor deficits and gliosis in the ventral midbrain and hippocampus using immunohistochemistry, western blot and glucocerebrosidase assays. Additionally, primary microglia from wild-type and Gba1E326K/E326K mice were treated with α-synuclein preformed fibrils to study microglia activation, pro-inflammatory cytokines, reactive astrocyte formation and neuronal death through quantitative PCR, western blot and immunocytochemistry analyses. We also evaluated the effects of gut inoculation of α-synuclein preformed fibrils in Gba1 E326K mice at 7 months and striatal inoculation at 10 months after injection, assessing motor/non-motor symptoms, α-synuclein pathology, neuroinflammation, gliosis and neurodegeneration via behavioural tests, immunohistochemistry and western blot assays. At 24 months, Gba1 E326K knock-in mice showed reduced glucocerebrosidase enzymatic activity and glucosylceramide build-up in the ventral midbrain and hippocampus. Increased pro-inflammatory cytokines and reactive astrocytes were observed in microglia and astrocytes from Gba1 E326K mice treated with pathological α-synuclein preformed fibrils. Gut inoculation of α-synuclein preformed fibrils increased Lewy body accumulation in the hippocampal dentate gyrus, with heightened microglia and astrocyte activation and worsened non-motor symptoms. Intrastriatal injection of α-synuclein preformed fibrils induced motor deficits, reactive glial protein accumulation and tauopathy in the prefrontal cortex and hippocampus of Gba1 E326K mice. GBA1 deficiency attributable to the Gba1 E326K mutation exacerbates neuroinflammation and promotes pathogenic α-synuclein transmission, intensifying disease pathology in Parkinson's disease models. This study enhances our understanding of how the Gba1 E326K mutation contributes to neuroinflammation and the spread of pathogenic α-synuclein in the brain, suggesting new therapeutic strategies for Parkinson's disease and related synucleinopathies.

Identification of isoAsp7-Aβ as a major Aβ variant in Alzheimer's disease, dementia with Lewy bodies and vascular dementia

The formation of amyloid-β (Aβ) aggregates in brain is a neuropathological hallmark of Alzheimer's disease (AD). However, there is mounting evidence that Aβ also plays a pathogenic role in other types of dementia and that specific post-translational Aβ modifications contribute to its pathogenic profile. The objective of this study was to test the hypothesis that distinct types of dementia are characterized by specific patterns of post-translationally modified Aβ variants. We conducted a comparative analysis and quantified Aβ as well as Aβ with pyroglutamate (pGlu3-Aβ and pGlu11-Aβ), N-truncation (Aβ(4-X)), isoaspartate racemization (isoAsp7-Aβ and isoAsp27-Aβ), phosphorylation (pSer8-Aβ and pSer26-Aβ) or nitration (3NTyr10-Aβ) modification in post mortem human brain tissue from non-demented control subjects in comparison to tissue classified as pre-symptomatic AD (Pre-AD), AD, dementia with Lewy bodies and vascular dementia. Aβ modification-specific immunohistochemical labelings of brain sections from the posterior superior temporal gyrus were examined by machine learning-based segmentation protocols and immunoassay analyses in brain tissue after sequential Aβ extraction were carried out. Our findings revealed that AD cases displayed the highest concentrations of all Aβ variants followed by dementia with Lewy bodies, Pre-AD, vascular dementia and non-demented controls. With both analytical methods, we identified the isoAsp7-Aβ variant as a highly abundant Aβ form in all clinical conditions, followed by Aβ(4-X), pGlu3-Aβ, pGlu11-Aβ and pSer8-Aβ. These Aβ variants were detected in distinct plaque types of compact, coarse-grained, cored and diffuse morphologies and, with varying frequencies, in cerebral blood vessels. The 3NTyr10-Aβ, pSer26-Aβ and isoAsp27-Aβ variants were not found to be present in Aβ plaques but were detected intraneuronally. There was a strong positive correlation between isoAsp7-Aβ and Thal phase and a moderate negative correlation between isoAsp7-Aβ and performance on the Mini Mental State Examination. Furthermore, the abundance of all Aβ variants was highest in APOE 3/4 carriers. In aggregation assays, the isoAsp7-Aβ, pGlu3-Aβ and pGlu11-Aβ variants showed instant fibril formation without lag phase, whereas Aβ(4-X), pSer26-Aβ and isoAsp27-Aβ did not form fibrils. We conclude that targeting Aβ post-translational modifications, and in particular the highly abundant isoAsp7-Aβ variant, might be considered for diagnostic and therapeutic approaches in different types of dementia. Hence, our findings might have implications for current antibody-based therapies of AD.

Neuropsychiatric Symptom Profile in Alzheimer's Disease and Their Relationship With Functional Decline

OBJECTIVE

Understanding the course of individual neuropsychiatric symptoms (NPS) and their relationship with function is important for planning targeted interventions for preventing and delaying functional decline. This study aims to disentangle relative contributions of individual NPS on functional decline.

METHODS

Longitudinal study of 9,358 well-characterized participants with baseline diagnoses of Mild Cognitive Impairment or AD in the National Alzheimer's Coordinating Center Uniform Data Set. Function was measured using the Functional Assessment Questionnaire (FAQ). Clinician judgment of seven common behavioral symptoms were examined simultaneously: apathy-withdrawal, depressed mood, visual or auditory hallucinations, delusions, disinhibition, irritability, and agitation.

RESULTS

Apathy was the most common NPS at baseline (33.7%) and throughout follow-up, endorsed by clinicians in 63.7% of visits. Apathy was the most persistent with 36.7% of participants having clinician-endorsed apathy in ≥50% of their visits. Apathy strongly correlated with faster rate of functional decline. Compared to those who never had apathy, baseline FAQ was worse in those with intermittent or persistent/always apathy (intermittent: estimated coefficient ±SE=1.228±0.210, 95% CI=[0.817, 1.639]; persistent/always: 2.354±0.244 (95% CI=[1.876, 2.832], both p <0.001). Over time, rate of functional decline was faster in those with intermittent and persistent/always apathy (intermittent: 0.454±0.091, 95% CI=[0.276, 0.632]; persistent/always: 0.635±0.102, 95% CI=[0.436, 0.835], both p <0.001). Worse agitation, delusions, and hallucinations also correlated with functional decline, but magnitudes of the estimates were smaller.

CONCLUSION

Individual NPS may be sensitive targets for tracking longitudinal change in function. The study raises awareness of the need for more comprehensive assessment of functional decline in AD patients with noncognitive symptoms.

Neuroanatomical substrates of depression in dementia with Lewy bodies and Alzheimer's disease

Dementia with Lewy bodies (DLB) and Alzheimer's disease (AD) are often associated with depressive symptoms from the prodromal stage. The aim of the present study was to investigate the neuroanatomical correlates of depression in prodromal to mild DLB patients compared with AD patients. Eighty-three DLB patients, 37 AD patients, and 18 healthy volunteers were enrolled in this study. Depression was evaluated with the Mini International Neuropsychiatric Interview (MINI), French version 5.0.0. T1-weighted three-dimensional anatomical images were acquired for all participants. Regression and comparison analyses were conducted using a whole-brain voxel-based morphometry (VBM) approach on the grey matter volume (GMV). DLB patients presented a significantly higher mean MINI score than AD patients (p = 0.004), 30.1% of DLB patients had clinical depression, and 56.6% had a history of depression, while 0% of AD patients had clinical depression and 29.7% had a history of depression. VBM regression analyses revealed negative correlations between the MINI score and the GMV of right prefrontal regions in DLB patients (p < 0.001, uncorrected). Comparison analyses between DLB patients taking and those not taking an antidepressant mainly highlighted a decreased GMV in the bilateral middle/inferior temporal gyrus (p < 0.001, uncorrected) in treated DLB patients. In line with the literature, our behavioral analyses revealed higher depression scores in DLB patients than in AD patients. We also showed that depressive symptoms in DLB are associated with decreased GMV in right prefrontal regions. Treated DLB patients with long-standing depression would be more likely to experience GMV loss in the bilateral middle/inferior temporal cortex. These findings should be taken into account when managing DLB patients.

Spatial-temporal dynamic evolution of lewy body dementia by metabolic PET imaging

PURPOSE

Lewy body dementia (LBD) is a neurodegenerative disease with high heterogeneity and complex pathogenesis. Our study aimed to use disease progression modeling to uncover spatial-temporal dynamic evolution of LBD in vivo, and to explore differential profiles of clinical features, glucose metabolism, and dopaminergic function among different evolution-related subtypes.

METHODS

A total of 123 participants (31 healthy controls and 92 LBD patients) who underwent 18F-FDG PET scans were retrospectively enrolled. 18F-FDG PET-based Subtype and Stage Inference (SuStaIn) model was established to illustrate spatial-temporal evolutionary patterns and categorize relevant subtypes. Then subtypes and stages were further related to clinical features, glucose metabolism, and dopaminergic function of LBD patients.

RESULTS

This 18F-FDG PET imaging-based approach illustrated two distinct patterns of neurodegenerative evolution originating from the neocortex and basal ganglia in LBD and defined them as subtype 1 and subtype 2, respectively. There were obvious differences between subtypes. Compared with subtype 1, subtype 2 exhibited a greater proportion of male patients (P = 0.045) and positive symptoms such as visual hallucinations (P = 0.033) and fluctuating cognitions (P = 0.033). Cognitive impairment, metabolic abnormalities, dopaminergic dysfunction and progression were all more severe in subtype 2 (all P < 0.05). In addition, a strong association was observed between SuStaIn subtypes and two clinical phenotypes (Parkinson's disease dementia and dementia with Lewy bodies) (P = 0.005).

CONCLUSIONS

Our findings based on 18F-FDG PET and data-driven model illustrated spatial-temporal dynamic evolution of LBD and categorized novel subtypes with different evolutionary patterns, clinical and imaging features in vivo. The evolution-related subtypes are associated with LBD clinical phenotypes, which supports the perspective of existence of distinct entities in LBD spectrum.

Investigating the feasibility of 18F-flortaucipir PET imaging in the antemortem diagnosis of primary age-related tauopathy (PART): An observational imaging-pathological study

INTRODUCTION

Primary age-related tauopathy (PART) is characterized by neurofibrillary tangles and minimal β-amyloid deposition, diagnosed postmortem. This study investigates 18F-flortaucipir (FTP) PET imaging for antemortem PART diagnosis.

METHODS

We analyzed FTP PET scans from 50 autopsy-confirmed PART and 13 control subjects. Temporal lobe uptake was assessed both qualitatively and quantitatively. Demographic and clinicopathological characteristics and voxel-level uptake using SPM12 were compared between FTP-positive and FTP-negative cases. Intra-reader reproducibility was evaluated with Krippendorff's alpha.

RESULTS

Minimal/mild and moderate FTP uptake was seen in 32% of PART cases and 62% of controls, primarily in the left inferior temporal lobe. No demographic or clinicopathological differences were found between FTP-positive and FTP-negative cases. High intra-reader reproducibility (α = 0.83) was noted.

DISCUSSION

FTP PET imaging did not show a specific uptake pattern for PART diagnosis, indicating that in vivo PART identification using FTP PET is challenging. Similar uptake in controls suggests non-specific uptake in PART.

HIGHLIGHTS

18F-flortaucipir (FTP) PET scans were analyzed for diagnosing PART antemortem. 32% of PART cases had minimal/mild FTP uptake in the left inferior temporal lobe. Similar to PART FTP uptake was found in 62% of control subjects. No specific uptake pattern was found, challenging in vivo PART diagnosis.

The updated prevalence and risk factors of dementia in old adults in China: A cross-sectional study

BACKGROUND

The continuously increasing aging population and life expectancy have led to an inconsistent and underestimated dementia prevalence in China. An updated epidemiologic study is urgently needed.

OBJECTIVE

To update the prevalence rate and risk factors of dementia in China.

METHODS

For this national cross-sectional study, 20,438 participants aged ≥65 from 28 communities and 56 villages from 14 centers were recruited using a multistage cluster sampling design between May 2019 and December 2019. Participants were assessed with a series of clinical and neuropsychological measurements. The prevalence rates of dementia, Alzheimer's disease (AD), and vascular dementia (VaD), as well as the risk factors, were calculated using multivariate-adjusted models.

RESULTS

The crude prevalence rates were 9.1% (95% CI, 8.7%-9.5%) for dementia, 6.0% (95% CI, 5.7%-6.3%) for AD, 1.4% (95% CI, 1.2%-1.5%) for VaD, and 1.8% (95% CI, 1.6%-2.0%) for other dementias in a population aged ≥65 years. The overall sex- and age-standardized prevalence was 8.8%. Apart from VaD, the prevalence rates of dementia and AD were higher in females than males (10.3% versus 7.7%, respectively). Moreover, the prevalence rates of dementia and AD increased significantly with age. Being unmarried and having fewer social activities increased the risks of dementia and main subtypes. Risk factors were not exactly the same for participants with AD and VaD.

CONCLUSIONS

The prevalence of dementia is increased and almost comparable with that of developed countries for individuals aged ≥65 years. These findings may serve as new evidence for government interventions in aging.

Multisite Skin Biopsies vs Cerebrospinal Fluid for Prion Seeding Activity in the Diagnosis of Prion Diseases

Importance

Recent studies have revealed that autopsy skin samples from cadavers with prion diseases (PRDs) exhibited a positive prion seeding activity similar to cerebrospinal fluid (CSF). It is worthwhile to validate the findings with a large number of biopsy skin samples and compare the clinical value of prion seeding activity between skin biopsies and concurrent CSF specimens.

Objective

To compare the prion seeding activity of skin biopsies and CSF samples and to determine the effectiveness of combination of the skin biopsies from multiple sites and numerous dilutions on the diagnosis for various types of PRDs.

Design, Setting, and Participants

In the exploratory cohort, patients were enrolled from September 15, 2021, to December 15, 2023, and were followed up every 3 months until April 2024. The confirmatory cohort enrolled patients from December 16, 2023, to June 31, 2024. The exploratory cohort was conducted at a single center, the neurology department at Xuanwu Hospital. The confirmatory cohort was a multicenter study involving 4 hospitals in China. Participants included those diagnosed with probable sporadic Creutzfeldt-Jakob disease or genetically confirmed PRDs. Patients with uncertain diagnoses or those lost to follow-up were excluded. All patients with PRDs underwent skin sampling at 3 sites (the near-ear area, upper arm, lower back, and inner thigh), and a portion of them had CSF samples taken simultaneously. In the confirmatory cohort, a single skin biopsy site and CSF samples were simultaneously collected from a portion of patients with PRDs.

Exposures

The skin and CSF prion seeding activity was assessed using the real-time quaking-induced conversion (RT-QUIC) assay, with rHaPrP90-231, a Syrian hamster recombinant prion protein, as the substrate. In the exploratory cohort, skin samples were tested at dilutions of 10-2 through 10-4. In the confirmatory cohort, skin samples were tested at a dilution of 10-2. A total of four 15-μL wells of CSF were used in the RT-QUIC assay.

Main Outcomes and Measures

Correlations between RT-QUIC results from the skin and CSF and the final diagnosis of enrolled patients.

Results

In the exploratory cohort, the study included 101 patients (mean [SD] age, 60.9 [10.2] years; 63 female [62.4%]) with PRD and 23 patients (mean [SD] age, 63.4 [9.1] years; 13 female [56.5%]) without PRD. A total of 94 patients had CSF samples taken simultaneously with the skin biopsy samples. In the confirmatory cohort, a single skin biopsy site and CSF sample were taken simultaneously in 43 patients with PRDs. Using an experimental condition of 10-2 dilution, the RT-QUIC positive rates of skin samples from different sites were comparable with those of the CSF (skin: 18 of 26 [69.2%] to 74 of 93 [79.6%] vs CSF: 71 of 94 [75.5%]). When tested at 3 different dilutions, all skin sample positivity rates increased to over 80.0% (79 of 93 for the near-ear area, 21 of 26 for the upper arm, 77 of 92 for the lower back, and 78 of 92 for the inner thigh). Combining samples from skin sites near the ear, inner thigh, and lower back in pairs yielded positivity rates exceeding 92.1% (93 of 101), significantly higher than CSF alone (71 of 94 [75.5%]; P =.002). When all skin sample sites were combined and tested at 3 dilution concentrations for RT-QUIC, the sensitivity reached 95.0% (96 of 101). In the confirmatory cohort, the RT-QUIC positive rate of a single skin biopsy sample was slightly higher than that of the CSF (34 of 43 [79.1%] vs 31 of 43 [72.1%]; P = .45).

Conclusions and Relevance

Results of this diagnostic study suggest that the sensitivity of an RT-QUIC analysis of a combination of 2 or more skin sites was superior to that of CSF in diagnosing PRDs.

A General Neurologist's Practical Diagnostic Algorithm for Atypical Parkinsonian Disorders: A Consensus Statement

Purpose of Review

The most common four neurodegenerative atypical parkinsonian disorders (APDs) are progressive supranuclear palsy (PSP), multiple system atrophy (MSA), corticobasal syndrome (CBS), and dementia with Lewy bodies (DLB). Their formal diagnostic criteria often require subspecialty experience to implement as designed and all require excluding competing diagnoses without clearly specifying how to do that. Validated diagnostic criteria are not available at all for many of the other common APDs, including normal pressure hydrocephalus (NPH), vascular parkinsonism (VP), or drug-induced parkinsonism (DIP). APDs also include conditions of structural, genetic, vascular, toxic/metabolic, infectious, and autoimmune origin. Their differential diagnosis can be challenging early in the course, if the presentation is atypical, or if a rare or non-neurodegenerative condition is present. This review equips community general neurologists to make an early provisional diagnosis before, or in place of, referral to a tertiary center. Early diagnosis would allay diagnostic uncertainty, allow prompt symptomatic management, provide disease-specific information and support resources, avoid further pointless testing and treatments, and create the possibility of trial referral.

Recent Findings

We address 64 APDs using one over-arching flow diagram and a series of detailed tables. Most instances of APDs can be diagnosed with a careful history and neurological exam, along with a non-contrast brain MRI. Additional diagnostic tests are rarely needed but are delineated where applicable. Our diagnostic algorithm encourages referral to a tertiary center whenever the general neurologist feels it would be in the patient's best interest. Our algorithm emphasizes that the diagnosis of APDs is an iterative process, refined with the appearance of new diagnostic features, availability of new technology, and advances in scientific understanding of the disorders. Clinicians' proposals for all diagnostic tests for the APDs, including repeat visits, should be discussed with patients and their families to ensure that the potential information to be gained aligns with their larger clinical goals.

Summary

We designed this differential diagnostic algorithm for the APDs to enhance general neurologists' diagnostic skills and confidence and to help them address the less common or more ambiguous cases.

Post-mortem neuropathology of idiopathic rapid eye movement sleep behaviour disorder: a case series

BACKGROUND

Idiopathic rapid eye movement (REM) sleep behaviour disorder (IRBD) is thought to be an early stage of α-synuclein-related neurodegenerative diseases. Nevertheless, the definitive identification of its biological substrate can be determined only by post-mortem neuropathology. We aimed to describe the post-mortem neuropathology of individuals with IRBD who developed or did not develop a neurodegenerative disease before death.

METHODS

In this case series at the Hospital Clinic de Barcelona, Barcelona, Spain, we examined post-mortem brain tissue and spinal cords from individuals diagnosed with IRBD by video polysomnography who became donors to the Neurological Tissue Bank between May 28, 2005, and March 23, 2023. We performed post-mortem neuropathology to assess the presence and distribution of neuronal loss, gliosis, and protein aggregates using antibodies against α-synuclein, amyloid β, phosphorylated tau, three-repeat and four-repeat tau isoforms, and TDP-43. Comparative statistical analyses were not done because of the small sample size, but differences observed across the nuclei and brain structures were described.

FINDINGS

The brains and spinal cords of 20 individuals with IRBD were examined (19 [95%] men, one [5%] woman). Their clinical antemortem diagnoses were of IRBD without any other neurological disorder in three (15%), Parkinson's disease without dementia in two (10%), Parkinson's disease dementia (PDD) in three (15%), and dementia with Lewy bodies (DLB) in 12 (60%) individuals. Post-mortem neuropathological diagnoses were Lewy body disease in 19 (95%) and multiple system atrophy (MSA) in one (5%). All participants with Lewy body disease and MSA showed neuronal loss, gliosis, and α-synuclein deposits in neurons and astrocytes. In all participants, α-synuclein was found in the structures that regulate REM sleep atonia (eg, subcoeruleus nucleus, gigantocellular reticular nucleus, laterodorsal tegmentum, and amygdala). Coexistent pathologies were found in all participants, including Alzheimer's disease pathology (amyloid β plaques and neurofibrillary tangles) in 14 (70%), ageing-related tau astrogliopathy in 12 (60%), cerebral amyloid angiopathy in 11 (55%), argyrophilic grain disease in four (20%), limbic-predominant age-related TDP-43 encephalopathy in four (20%), and early changes indicative of progressive supranuclear palsy in three (15%). In individuals with IRBD without any other neurological disorder and in those who developed Parkinson's disease without dementia, α-synuclein was found in the brainstem and limbic system and rarely in the cortex, whereas coexisting proteinopathies were few and showed mild pathological burden. In contrast, in individuals who developed PDD or DLB, α-synuclein had diffuse distribution in the brainstem, limbic system, and cortex, and multiple comorbid pathologies were common, particularly those related to Alzheimer's disease.

INTERPRETATION

Although limited by a relatively small sample size, our observations provide strong neuropathological evidence that IRBD is an early stage of α-synuclein-related neurodegenerative disease. Concomitant pathologies are frequent and their role remains to be clarified: some might have contributed to the development of dementia, but some might be age-related changes. Our findings could inform the design of clinical trials of compounds that target specific pathological proteins (eg, α-synuclein and amyloid β) in people with IRBD.

FUNDING

Fundación BBVA-Hospital Clínic de Barcelona.

Astrocytic Ca2+ activation by chemogenetics mitigates the effect of kainic acid-induced excitotoxicity on the hippocampus

Astrocytes play a multifaceted role regulating brain glucose metabolism, ion homeostasis, neurotransmitters clearance, and water dynamics being essential in supporting synaptic function. Under different pathological conditions such as brain stroke, epilepsy, and neurodegenerative disorders, excitotoxicity plays a crucial role, however, the contribution of astrocytic activity in protecting neurons from excitotoxicity-induced damage is yet to be fully understood. In this work, we evaluated the effect of astrocytic activation by Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) on brain glucose metabolism in wild-type (WT) mice, and we investigated the effects of sustained astrocyte activation following an insult induced by intrahippocampal (iHPC) kainic acid (KA) injection using 2-deoxy-2-[18F]-fluoro-D-glucose (18F-FDG) positron emission tomography (PET) imaging, along with behavioral test, nuclear magnetic resonance (NMR) spectroscopy and histochemistry. Astrocytic Ca2+ activation increased the 18F-FDG uptake, but this effect was not found when the study was performed in knock out mice for type-2 inositol 1,4,5-trisphosphate receptor (Ip3r2-/-) nor in floxed mice to abolish glucose transporter 1 (GLUT1) expression in hippocampal astrocytes (GLUT1ΔGFAP). Sustained astrocyte activation after KA injection reversed the brain glucose hypometabolism, restored hippocampal function, prevented neuronal death, and increased hippocampal GABA levels. The findings of our study indicate that astrocytic GLUT1 function is crucial for regulating brain glucose metabolism. Astrocytic Ca2+ activation has been shown to promote adaptive changes that significantly contribute to mitigating the effects of KA-induced damage. This evidence suggests a protective role of activated astrocytes against KA-induced excitotoxicity.

Cognitive Impact of β-Amyloid Load in the Rapid Eye Movement Sleep Behavior Disorder-Lewy Body Disease Continuum

BACKGROUND

Rapid eye movement sleep behavior disorder (RBD) is linked to the diffuse-malignant subtype and higher cognitive burden in Lewy body disease (LBD).

OBJECTIVE

This study explores brain β-amyloid deposition and its association with cognitive decline across the RBD-LBD continuum.

METHODS

Patients with isolated RBD (iRBD), Parkinson's disease with probable RBD (PDRBD), and dementia with Lewy bodies with probable RBD (DLBRBD) underwent 18F-florbetaben positron emission tomography, 3T magnetic resonance imaging scans, and comprehensive neuropsychological assessments. Subjects were categorized as cognitively normal (NC), mild cognitive impairment (MCI), or dementia. Global and regional standardized uptake value ratios (SUVR) were estimated in predefined cognitive volumes of interest (VOI) derived from voxel-wise comparison analysis among the cognitive groups, namely the prefrontal, parietal, precentral cortices, lingual gyrus, and supplementary motor area. Generalized linear models assessed the relationship between 18F-florbetaben SUVRs and neuropsychological testing, adjusting for age and sex. Subgroup analysis focused on the polysomnography-confirmed iRBD-continuum subset (n = 41) encompassing phenoconverters and nonconverters in our prospective iRBD cohort.

RESULTS

Eighty-six subjects were classified as follows: 14 NC, 54 MCI, and 18 dementia. The proportion of positive β-amyloid scans increased with advanced cognitive stages (P = 0.038). β-Amyloid signals in cognitive VOIs were elevated in subgroups showing impairment in Trail-Making Test B (TMT-B). A linear association between TMT-B z score and global cortical β-amyloid levels was observed in the iRBD-continuum subset (P = 0.013).

CONCLUSION

Cortical β-amyloid accumulates with declines in executive function within the RBD-LBD continuum. TMT-B performance may be a useful marker associating with β-amyloid load, particularly in the iRBD population. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Evaluating Electroconvulsive Therapy for Dementia With Lewy Bodies, Including the Prodromal Stage: A Retrospective Study on Safety and Efficacy

OBJECTIVES

Managing symptoms, notably psychiatric symptoms, in dementia with Lewy bodies (DLB) is complex, affecting both patients and caregivers. People with DLB often react poorly to antipsychotics, limiting treatment options. Although electroconvulsive therapy (ECT)'s potential for DLB is acknowledged, evidence is scarce owing to limited studies. This study investigated ECT's effectiveness and safety for DLB and prodromal DLB with antecedent psychiatric symptoms.

METHODS

This retrospective study investigated people with DLB (N = 12) and mild cognitive impairment (MCI) with LB (N = 13), a prodromal form of DLB, who underwent ECT for psychiatric symptoms and had abnormal findings confirmed using dopamine transporter single-photon emission computed tomography and 123I-metaiodobenzylguanidine myocardial scintigraphy. We reviewed these patients' medical records and determined the severity of psychotic symptoms before and 1 week after the final ECT session with the Clinical Global Impressions Severity Scale (CGI-S). Improvement in psychotic symptoms was evaluated approximately 1 week after the final ECT session using the CGI Improvement Scale (CGI-I). Additionally, we assessed cognitive function and dementia severity before and after ECT, as well as any adverse events caused by ECT.

RESULTS

ECT significantly improved psychiatric symptoms, as assessed using the CGI-S, with CGI-I reports in the order of 60% "very much improved," 20% "much improved," 16% "minimally improved," and 4% "no change." Parkinsonism improved (Hoehn and Yahr: 1.76 ± 1.2 before vs. 1.04 ± 0.7 after, p < 0.001) as did dementia severity (Clinical Dementia Rating, p = 0.037). Adverse events included delirium in 24% of patients and amnesia in 4% of patients. ECT did not worsen cognitive function.

CONCLUSIONS

ECT for DLB and MCI with LB with antecedent psychiatric symptoms appears safe and effective in managing psychiatric symptoms and Parkinsonism. Further large-scale multicenter studies are warranted to conclusively establish its effectiveness and safety.