Parkinson's and Lewy body dementia CSF biomarkers

m6A Demethylase FTO-Mediated Upregulation of BAP1 Induces Neuronal Ferroptosis via the p53/SLC7A11 Axis in the MPP+/MPTP-Induced Parkinson's Disease Model

Background: Parkinson's disease (PD) is a neurodegenerative disorder characterized by the involvement of ferroptosis in its pathological mechanism. In this study, the effects and mechanism of BRCA1-associated protein 1 (BAP1) on neuronal ferroptosis in PD were evaluated. Methods: A PD mouse model was constructed by injecting mice with MPTP. Nissl staining, immunohistochemistry, immunofluorescence, and Prussian blue staining evaluated histopathology and iron distribution. The PD cell model was constructed by subjecting SK-N-SH cells to MPP+. The m6A level of BAP1 was assessed by MeRIP. mRNA levels of BAP1, FTO, IGF2BP1, METTL3, YTHDF2, and SLC7A11 were evaluated utilizing RT-qPCR. Protein levels of BAP1, FTO, IGF2BP1, METTL3, YTHDF2, SLC7A11, and p53 were measured by Western blot. Cell viability was assessed using CCK-8 assay, and TUNEL was used for assessing apoptosis. The levels of MDA, GSH, SOD, and Fe2+ were also measured. The interactions among molecules were verified using RIP assay, dual luciferase reporter assay, and ChIP assay. Results: SK-N-SH cells treated with MPP+ showed a decrease in overall m6A levels of BAP1. FTO facilitated m6A demethylation of BAP1, leading to an increased level of expression of BAP1. m6A-binding protein, YTHDF2 recognized and decayed methylated mRNA of BAP1, leading to the reduced BAP1 stability. The FTO/BAP1 axis promoted MPP+-induced ferroptosis by suppressing SLC7A11. BAP1, in collaboration with p53, reduced the level of expression of SLC7A11. Knocking down BAP1 mitigated ferroptosis in an MPTP mouse model. Conclusion: m6A-mediated modification of BAP1 regulates neuronal ferroptosis by cooperating with p53 to decrease the level of SLC7A11. Thus, BAP1 may be a potential therapeutic target for PD treatment.

Cerebrospinal Fluid Biomarkers for Diagnosis of Parkinson's disease: A Systematic Review

Parkinson's disease (PD) is a neurodegenerative disorder that presents challenges in early diagnosis, particularly in its prodromal stages. PD is characterized by motor and non-motor symptoms, and it remains challenging to diagnose in its early stages. The use of cerebrospinal fluid (CSF) biomarkers has shown promise as an adjunctive tool for early detection and monitoring of disease progression. The aim of this systematic review was to evaluate the diagnostic potential of CSF biomarkers in PD. We focused on assessing the reliability, sensitivity, specificity, and utility of various CSF biomarkers for the early and accurate diagnosis of PD. A comprehensive search was conducted across multiple databases, including PubMed, Scopus, and Web of Science, to identify relevant studies published from January 2015 to November 2024. Studies were included if they examined CSF biomarkers in human PD patients, and compared to healthy controls or other neurodegenerative diseases. Data on sample size, biomarker types, and diagnostic accuracy were extracted from 34 eligible studies. The methodological quality of the studies was assessed using standard tools, and a qualitative synthesis was performed using PRISMA tools. Analysis was done to assess the diagnostic performance of selected biomarkers. The review identified several promising CSF biomarkers, including α-synuclein, neurofilament light chain (NfL), DJ-1, tau, and exosomal biomarkers. Of these, α-synuclein demonstrated the highest diagnostic accuracy with a sensitivity of 70-85% and specificity of 75-90%. NfL also showed a strong sensitivity (65-85%) for detecting neuronal injury, while DJ-1 exhibited a high specificity for early-stage PD. Multi-biomarker panels, including combinations of α-synuclein, tau, and NfL, demonstrated superior diagnostic accuracy compared to individual biomarkers. The variability in the biomarkers' performance was noted across studies, indicating the need for standardization in biomarker assays and further validation through larger, multicenter studies. CSF biomarkers hold significant promise for improving the diagnosis of PD, particularly when used in combination. However, more research is needed to establish standardized protocols and evaluate their role in clinical practice. Multi-biomarker panels show potential as a diagnostic tool, but further investigation is required to confirm their clinical utility and cost-effectiveness in diverse populations. Future studies should focus on the longitudinal tracking of these biomarkers for monitoring disease progression and therapeutic response.

Genomic and Transcriptomic Approaches Advance the Diagnosis and Prognosis of Neurodegenerative Diseases

Neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS), represent a growing societal challenge due to their irreversible progression and significant impact on patients, caregivers, and healthcare systems. Despite advances in clinical and imaging-based diagnostics, these diseases are often detected at advanced stages, limiting the effectiveness of therapeutic interventions. Recent breakthroughs in genomic and transcriptomic technologies, including whole-genome sequencing, single-cell RNA sequencing (scRNA-seq), and CRISPR-based screens, have revolutionized the field, offering new avenues for early diagnosis and personalized prognosis. Genomic approaches have elucidated disease-specific genetic risk factors and molecular pathways, while transcriptomic studies have identified stage-specific biomarkers that correlate with disease progression and severity. Furthermore, genome-wide association studies (GWAS), polygenic risk scores (PRS), and spatial transcriptomics are enabling the stratification of patients based on their risk profiles and prognostic trajectories. Advances in functional genomics have uncovered actionable targets, such as ATXN2 in ALS and TREM2 in AD, paving the way for tailored therapeutic strategies. Despite these achievements, challenges remain in translating genomic discoveries into clinical practice due to disease heterogeneity and the complexity of neurodegenerative pathophysiology. Future integration of genetic technologies holds promise for transforming diagnostic and prognostic paradigms, offering hope for improved patient outcomes and precision medicine approaches.

Aβ42 biomarker linked to insula, striatum, thalamus and claustrum in dementia with Lewy bodies

The differential mechanisms between proteinopathies and neurodegeneration in Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) remain unclear. To address this issue, we conducted a voxel-based morphometry and cerebrospinal fluid biomarker (α-synuclein, Aβ42, t-Tau and p-Tau181) level correlation study in patients with DLB, AD and mixed cases (AD + DLB). Cerebrospinal fluid samples obtained by lumbar puncture and whole-brain T1-weighted images were collected in the AlphaLewyMA cohort. Within the cohort, 65 DLB patients, 18 AD patients, 24 AD + DLB patients and 16 neurological control subjects (NC) were clinically diagnosed. Correlation analyses were performed between cerebrospinal fluid biomarker levels and gray matter volumes using a voxel-based morphometry approach. A mediation analysis was performed to explore the role of gray matter volumes in the relationship between Aβ42 levels and clinical severity (MMSE scores). We observed a significant positive correlation between gray matter volumes and cerebrospinal fluid Aβ42 levels in the insula, the striatal regions, the right thalamus, and the claustrum in DLB patients (pFDR < 0.05). Mediation analysis revealed that gray matter volumes significantly mediated the relationship between Aβ42 levels and MMSE scores in DLB patients. We found no significant correlation with gray matter volumes for α-synuclein, p-Tau181 or t-Tau in DLB patients (pFDR < 0.05). We found no significant correlations in the AD, AD + DLB and NC groups for any of the biomarkers (pFDR < 0.05). The specific correlation between a reduced cerebrospinal fluid Aβ42 level and lower gray matter volumes in insula, striatum, thalamus, and claustrum in DLB patients suggests a prominent role for amyloidopathy in promoting brain atrophy in key regions of the disease.

Cerebrospinal-fluid biomarkers for predicting phenoconversion in patients with isolated rapid-eye movement sleep behavior disorder

STUDY OBJECTIVES

Patients with isolated rapid-eye-movement sleep behavior disorder (iRBD) have an increased risk of developing neurodegenerative diseases. This study assessed cerebrospinal-fluid (CSF) biomarkers of neurodegeneration and blood-brain barrier (BBB) alteration in patients with iRBD compared to controls and ascertain whether these biomarkers may predict phenoconversion to alpha-synucleinopathies (Parkinson's Disease (PD), Dementia with Lewy bodies (DLB), Multiple System Atrophy (MSA)).

METHODS

Patients and controls underwent between 2012 and 2016 a neurological assessment, a lumbar puncture for CSF biomarker analysis (β-amyloid42 - Aβ42; total-tau, and phosphorylated tau), and BBB alteration (CSF/serum albumin ratio). All patients with iRBD were followed until 2021 and then classified into patients who converted to alpha-synucleinopathies (iRBD converters, cRBD) or not (iRBD non-converters, ncRBD).

RESULTS

Thirty-four patients with iRBD (mean age 67.12 ± 8.14) and 33 controls (mean age 64.97 ± 8.91) were included. At follow-up (7.63 ± 3.40 years), eight patients were ncRBD and 33 patients were cRBD: eleven converted to PD, 10 to DLB, and two to MSA. Patients with iRBD showed lower CSF Aβ42 levels and higher CSF/serum albumin ratio than controls. Cox regression analysis showed that the phenoconversion rate increases with higher motor impairment (hazard ratio [HR] = 1.23, p = 0.032). CSF Aβ42 levels predicted phenoconversion to DLB (HR = 0.67, p = 0.038) and BBB alteration predicted phenoconversion to PD (HR = 1.20, p = 0.038).

DISCUSSION

This study showed that low CSF Aβ42 levels and high BBB alteration may predict the phenoconversion to DLB and PD in patients with iRBD, respectively. These findings highlight the possibility to discriminate phenoconversion in iRBD patients through CSF biomarkers; however, further studies are needed.

Cerebrospinal fluid and blood serum biomarkers in neurodegenerative proteinopathies: A prospective, open, cross-correlation study

Neurodegenerative diseases are a broad heterogeneous group affecting the nervous system. They are characterized, from a pathophysiological perspective, by the selective involvement of a subpopulation of nerve cells with a consequent clinical picture of a disease. Clinical diagnoses of neurodegenerative diseases are quite challenging and often not completely accurate because of their marked heterogeneity and frequently overlapping clinical pictures. Efforts are being made to define sufficiently specific and sensitive markers for individual neurodegenerative diseases or groups of diseases in order to increase the accuracy and speed of clinical diagnosis. Thus said, this present research aimed to identify biomarkers in the cerebrospinal fluid (CSF) and serum (α-synuclein [α-syn], tau protein [t-tau], phosphorylated tau protein [p-tau], β-amyloid [Aβ], clusterin, chromogranin A [chromogrA], cystatin C [cyst C], neurofilament heavy chains [NFH], phosphorylated form of neurofilament heavy chains [pNF-H], and ratio of tau protein/amyloid beta [Ind tau/Aβ]) that could help in the differential diagnosis and differentiation of the defined groups of α-synucleinopathies and four-repeat (4R-) tauopathies characterized by tau protein isoforms with four microtubule-binding domains. In this study, we analyzed a cohort of 229 patients divided into four groups: (1) Parkinson's disease (PD) + dementia with Lewy bodies (DLB) (n = 82), (2) multiple system atrophy (MSA) (n = 25), (3) progressive supranuclear palsy (PSP) + corticobasal syndrome (CBS) (n = 30), and (4) healthy controls (HC) (n = 92). We also focused on analyzing the biomarkers in relation to each other with the intention of determining whether they are useful in distinguishing among individual proteinopathies. Our results indicate that the proposed set of biomarkers, when evaluated in CSF, is likely to be useful for the differential diagnosis of MSA versus 4RT. However, these biomarkers do not seem to provide any useful diagnostic information when assessed in blood serum.

Navigating Early Alzheimer's Diagnosis: A Comprehensive Review of Diagnostic Innovations

The hunt for early Alzheimer's disease detection has created cutting-edge diagnostic instruments with enormous promise. This article examines the many facets of these developments, focusing on how they have revolutionised diagnosis and patient outcomes. These tools make it possible to detect tiny brain changes even before they give birth to clinical symptoms by combining cutting-edge biomarkers, neuroimaging methods, and machine-learning algorithms. A significant opportunity for therapies that can slow the course of the disease exists during this early detection stage. Additionally, these cutting-edge techniques improve diagnostic precision, objectivity, and accessibility. Liquid biopsies and blood-based biomarkers provide non-invasive alternatives, filling accessibility gaps in diagnosis. While issues with standardisation, ethics, and data integration continue, collaboration within research, clinical practice, and policy realms fuels positive developments. As technology advances, the way towards better Alzheimer's diagnosis becomes more evident, giving patients and families dealing with this difficult illness fresh hope. The synergy between scientific advancement and compassionate treatment is crucial for improving Alzheimer's disease diagnosis, as this paper emphasises.

The Sherpa hypothesis: Phenotype-Preserving Disordered Proteins stabilize the phenotypes of neurons and oligodendrocytes

Intrinsically disordered proteins (IDPs), which can interact with many partner proteins, are central to many physiological functions and to various pathologies that include neurodegeneration. Here, we introduce the Sherpa hypothesis, according to which a subset of stable IDPs that we term Phenotype-Preserving Disordered Proteins (PPDP) play a central role in protecting cell phenotypes from perturbations. To illustrate and test this hypothesis, we computer-simulate some salient features of how cells evolve and differentiate in the presence of either a single PPDP or two incompatible PPDPs. We relate this virtual experiment to the pathological interactions between two PPDPs, α-synuclein and Tubulin Polymerization Promoting Protein/p25, in neurodegenerative disorders. Finally, we discuss the implications of the Sherpa hypothesis for aptamer-based therapies of such disorders.

Differential associations of clinical features with cerebrospinal fluid biomarkers in dementia with Lewy bodies and Alzheimer's disease

AIM

To explore associations of cerebrospinal fluid biomarkers of neurodegeneration and amyloidosis with caregiver burden, cognition and functionality in dementia with Lewy bodies (DLB) paired with late-onset Alzheimer's disease (AD) and healthy older people.

METHODS

Consecutive outpatients with DLB were matched with outpatients with AD according to sex, cognitive scores and dementia stage, and with cognitively healthy controls according to age and sex to investigate associations of cerebrospinal fluid amyloid-β (Aβ₄₂,Aβ₄₀,Aβ₃₈), tau, phospho-tau Thr₁₈₁, ubiquitin, α-synuclein and neurofilament light with caregiver burden, functionality, reverse digit span, a clock drawing test, Mini-Mental State Examination (MMSE) and Severe MMSE, adjusted for sex, age, education, dementia duration and APOE-ε4 alleles.

RESULTS

Overall, 27 patients with DLB (78.98 ± 9.0 years-old; eleven APOE-ε4 +) were paired with 27 patients with AD (81.50 ± 5.8 years-old; twelve APOE-ε4 +) and 27 controls (78.98 ± 8.7 years-old; four APOE-ε4 +); two-thirds were women. In AD, Aβ₄₂/Aβ₃₈ and Aβ₄₂ were lower, while tau/Aβ₄₂ and phospho-tau Thr₁₈₁/Aβ₄₂ were higher; α-synuclein/Aβ₄₂ was lower in DLB and higher in AD. The following corrected associations remained significant: in DLB, instrumental functionality was inversely associated with tau/phospho-tau Thr₁₈₁ and tau/Aβ₄₂, and reverse digit span associated with α-synuclein; in AD, instrumental functionality was inversely associated with neurofilament light, clock drawing test scores inversely associated with phospho-tau Thr₁₈₁/Aβ₄₂ and α-synuclein/Aβ₄₂, and Severe MMSE inversely associated with tau/Aβ₄₂ and tau/phospho-tau Thr₁₈₁.

CONCLUSIONS

Cerebrospinal fluid phospho-tau Thr₁₈₁ in DLB was similar to AD, but not Aβ₄₂. In associations with test scores, biomarker ratios were superior to isolated biomarkers, while worse functionality was associated with axonal degeneration only in AD.

The shift to a proteinopenia paradigm in neurodegeneration

The toxic proteinopathy paradigm has defined neurodegenerative disorders for over a century. This gain-of-function (GOF) framework posited that proteins become toxic when turned into amyloids (pathology), predicting that lowering its levels would translate into clinical benefits. Genetic observations used to support a GOF framework are equally compatible with a loss-of-function (LOF) framework, as the soluble pool of proteins rendered unstable by these mutations (e.g., APP in Alzheimer's disease, SNCA in Parkinson's disease) aggregate, becoming depleted. In this review, we highlight misconceptions that have prevented LOF from gaining currency. Some of these misconceptions include no phenotype in knock-out animals (there is neurodegenerative phenotype in knock-out animals) and high levels of proteins in patients (patients have lower levels of the proteins involved in neurodegeneration than healthy age-matched controls). We also expose the internal contradictions within the GOF framework, namely that (1) pathology can have both pathogenic and protective roles; (2) the neuropathology gold standard for diagnosis can be present in normal individuals and absent in those affected; (3) oligomers are the toxic species even if they are ephemeral and decrease over time. We therefore advocate for a paradigm shift from proteinopathy (GOF) to proteinopenia (LOF) based on the universal depletion of soluble functional proteins in neurodegenerative diseases (low amyloid-β 42 in Alzheimer's disease, low α-synuclein in Parkinson's disease, and low tau in progressive supranuclear palsy) and supported by the confluence of biologic, thermodynamic, and evolutionary principles with proteins having evolved to perform a function, not to become toxic, and where protein depletion is consequential. Such shift to a Proteinopenia paradigm is necessary to examining the safety and efficacy of protein replacement strategies instead of perpetuating a therapeutic paradigm with further antiprotein permutations.

Predictors of two-year mortality in patients with dementia with Lewy bodies

BACKGROUND

Data on adverse prognostic factors for mortality in patients with dementia with Lewy bodies (DLB) are limited. The objective of this study was to evaluate two-year mortality predictors in patients with DLB.

METHODS

: Individuals aged ≥ 60 years with a diagnosis of DLB, followed by a tertiary-referral geriatric outpatient clinic from 2006 to 2021, were assessed retrospectively using medical or patient records. The mortality status of the patients in the second year after diagnosis was determined. Demographic and clinical characteristics were reviewed to determine their impact on mortality prediction.

RESULTS

A total of 108 patients with DLB participated in this study. The mean age was 78.9 ± 6.6 years, and 49.1% were females. At the end of the two-year follow-up, 23 patients (21.3%) died and 85 patients (78.7%) were still alive. Malnutrition, and cognitive and functional impairments were significantly more common in the mortality group. Age, female sex, functional impairment, moderateto-severe clinical dementia rating, and malnutrition were associated with an increased mortality risk. On the multivariable analysis, malnutrition (HR = 5.00; 95% CI: 1.64-15.24; p: 0.005) was the only independent predictor of two-year-mortality.

DISCUSSION

Patients with DLB had an unfavorable survival outcomes. Approaches to prevent malnutrition can improve prognosis and reduce early mortality in this vulnerable group. However, further studies are needed to determine mortality risk factors in this population.

Global, in situ analysis of the structural proteome in individuals with Parkinson's disease to identify a new class of biomarker

Parkinson's disease (PD) is a prevalent neurodegenerative disease for which robust biomarkers are needed. Because protein structure reflects function, we tested whether global, in situ analysis of protein structural changes provides insight into PD pathophysiology and could inform a new concept of structural disease biomarkers. Using limited proteolysis-mass spectrometry (LiP-MS), we identified 76 structurally altered proteins in cerebrospinal fluid (CSF) of individuals with PD relative to healthy donors. These proteins were enriched in processes misregulated in PD, and some proteins also showed structural changes in PD brain samples. CSF protein structural information outperformed abundance information in discriminating between healthy participants and those with PD and improved the discriminatory performance of CSF measures of the hallmark PD protein α-synuclein. We also present the first analysis of inter-individual variability of a structural proteome in healthy individuals, identifying biophysical features of variable protein regions. Although independent validation is needed, our data suggest that global analyses of the human structural proteome will guide the development of novel structural biomarkers of disease and enable hypothesis generation about underlying disease processes.

Neurofilament light as a biomarker for motor decline in Parkinson’s disease

Objectives

The aim of this study was to determine whether neurofifilament light (NfL) could reflect motor decline and compare the predictive values of cerebrospinal fluid (CSF) and serum NfL in individuals with PD.

Methods

CSF/serum samples were collected from patients with PD and healthy controls (HCs) with motor assessments at baseline and after three years of follow-up from the Parkinson’s Progression Markers Initiative (PPMI). Multiple linear regression models and linear mixed-effects models were used to investigate the associations of motor assessments with baseline and longitudinal CSF/serum NfL. Associations between the change rates of motor assessments and CSF/serum NfL were further investigated via multiple linear regression models. Mediating effect analysis was used to research whether CSF alpha-synuclein (α-syn) acts as the mediator between NfL and motor assessments.

Results

We found patients with PD had higher baseline CSF/serum NfL levels than HCs. Both baseline CSF/serum NfLs and their change rates predicted measurable motor decline in PD assessed by different motor scores. Baseline serum NfL and its rate of change were strongly associated with CSF NfL levels in patients with PD (P < 0.001). Besides, there were also significant differences in CSF/serum NfL levels and predicted values of motor decline between men and women with PD. Mediating effect analysis showed CSF α-syn mediated the effect of CSF NfL on total Unified Parkinson’s Disease Rating Scale (UPDRS) scores and UPDRSIII with 30.6 and 20.2% mediation, respectively.

Conclusion

Our results indicated that NfL, especially serum NfL concentration, could serve as an easily accessible biomarker to monitor the severity and progression of motor decline in individuals with PD, especially in men with PD. Besides, CSF α-syn acts as a mediator between NfL and motor progression.

Oligomeropathies, inflammation and prion protein binding

The central role of oligomers, small soluble aggregates of misfolded proteins, in the pathogenesis of neurodegenerative disorders is recognized in numerous experimental conditions and is compatible with clinical evidence. To underline this concept, some years ago we coined the term oligomeropathies to define the common mechanism of action of protein misfolding diseases like Alzheimer, Parkinson or prion diseases. Using simple experimental conditions, with direct application of synthetic β amyloid or α-synuclein oligomers intraventricularly at micromolar concentrations, we could detect differences and similarities in the biological consequences. The two oligomer species affected cognitive behavior, neuronal dysfunction and cerebral inflammatory reactions with distinct mechanisms. In these experimental conditions the proposed mediatory role of cellular prion protein in oligomer activities was not confirmed. Together with oligomers, inflammation at different levels can be important early in neurodegenerative disorders; both β amyloid and α-synuclein oligomers induce inflammation and its control strongly affects neuronal dysfunction. This review summarizes our studies with β-amyloid or α-synuclein oligomers, also considering the potential curative role of doxycycline, a well-known antibiotic with anti-amyloidogenic and anti-inflammatory activities. These actions are analyzed in terms of the therapeutic prospects.

Effects of intraperitoneal injection of lipopolysaccharide-induced peripheral inflammation on dopamine neuron damage in rat midbrain

Introduction

Current studies have documented neuroinflammation is implicated in Parkinson's disease. Recently, growing evidence indicated peripheral inflammation plays an important role in regulation of neuroinflammation and thus conferring protection against dopamine (DA) neuronal damage. However, the underlying mechanisms are not clearly illuminated.

Methods

The effects of intraperitoneal injection of LPS (LPS_[i.p.])‐induced peripheral inflammation on substantia nigra (SN) injection of LPS (LPS_[SN])‐elicited DA neuronal damage in rat midbrain were investigated. Rats were intraperitoneally injected with LPS (0.5 mg/kg) daily for 4 consecutive days and then given single injection of LPS (8 μg) into SN with an interval of 0 (LPS_(i.p.) 0 day ± LPS_(SN)), 30 (LPS_(i.p.) 30 days ± LPS_(SN)), and 90 (LPS_(i.p.) 90 days ± LPS_(SN)) days after LPS_(i.p.) administration.

Results

LPS_(i.p.) increased the levels of inflammatory factors in peripheral blood in (LPS_(i.p.) 0 day ± LPS_(SN)). Importantly, in (LPS_(i.p.) 0 day ± LPS_(SN)) and (LPS_(i.p.) 30 days ± LPS_(SN)), LPS_(i.p.) attenuated LPS_(SN)‐induced DA neuronal loss in SN. Besides, LPS_(i.p.) reduced LPS_(SN)‐induced microglia and astrocytes activation in SN. Furtherly, LPS_(i.p.) reduced pro‐inflammatory M1 microglia markers mRNA levels and increased anti‐inflammatory M2 microglia markers mRNA levels. In addition, the increased T‐cell marker expression and the decreased M1 microglia marker expression and more DA neuronal survival were discerned at the same area of rat midbrain in LPS_(SN)‐induced DA neuronal damage 30 days after LPS_(i.p.) application.

Conclusion

This study suggested LPS_(i.p.)‐induced peripheral inflammation might cause T cells to infiltrate the brain to regulate microglia‐mediated neuroinflammation, thereby protecting DA neurons.

Recent advances in Lewy body dementia: A comprehensive review

Lewy Body Dementia is the second most frequent neurodegenerative illness proven to cause dementia, after Alzheimer's disease (AD). It is believed to be vastly underdiagnosed, as there is a significant disparity between the number of cases diagnosed clinically and those diagnosed via neuropathology at the time of postmortem autopsy. Strikingly, many of the pharmacologic treatments used to treat behavioral and cognitive symptoms in other forms of dementia exacerbate the symptoms of DLB. Therefore, it is critical to accurately diagnose DLB as these patients require a specific treatment approach. This article focuses on its pathophysiology, risk factors, differentials, and its diverse treatment modalities. In this study, an English language literature search was conducted on Medline, Cochrane, Embase, and Google Scholar till April 2022. The following search strings and Medical Subject Headings (MeSH) terms were used: "Lewy Body Dementia," "Dementia with Lewy bodies," and "Parkinson's Disease Dementia." We explored the literature on Lewy Body Dementia for its epidemiology, pathophysiology, the role of various genes and how they bring about the disease, biomarkers, its differential diagnoses and treatment options.

[Prognostic and diagnostic value of cerebrospinal fluid analysis in neurodegenerative dementia diseases]

Cerebrospinal fluid (CSF) analysis is an important diagnostic tool in the assessment of dementia. For the differentiation of Alzheimer's disease from other etiologies of dementia syndromes, established biological markers could be helpful to confirm a distinctive neuropathology. Whereas negative CSF findings can rule out the majority of primarily neurodegenerative disorders, overlapping biomarker profiles remain a diagnostic challenge. Therefore, it is important to interpret CSF results within a specific clinical context. Furthermore, atypical CSF data can be challenging and require profound knowledge of preanalytics, biomarker profiles and the broad spectrum of diseases associated with cognitive decline. Beyond the Alzheimer's disease clinical spectrum, current studies aim at investigating CSF biomarkers to better differentiate tauopathies, TDP43(Transactive response DNA binding protein 43 kDa)-proteinopathies and synucleinopathies.

Update on CSF Biomarkers in Parkinson's Disease

Progress in developing disease-modifying therapies in Parkinson’s disease (PD) can only be achieved through reliable objective markers that help to identify subjects at risk. This includes an early and accurate diagnosis as well as continuous monitoring of disease progression and therapy response. Although PD diagnosis still relies mainly on clinical features, encouragingly, advances in biomarker discovery have been made. The cerebrospinal fluid (CSF) is a biofluid of particular interest to study biomarkers since it is closest to the brain structures and therefore could serve as an ideal source to reflect ongoing pathologic processes. According to the key pathophysiological mechanisms, the CSF status of α-synuclein species, markers of amyloid and tau pathology, neurofilament light chain, lysosomal enzymes and markers of neuroinflammation provide promising preliminary results as candidate biomarkers. Untargeted approaches in the field of metabolomics provide insights into novel and interconnected biological pathways. Markers based on genetic forms of PD can contribute to identifying subgroups suitable for gene-targeted treatment strategies that might also be transferable to sporadic PD. Further validation analyses in large PD cohort studies will identify the CSF biomarker or biomarker combinations with the best value for clinical and research purposes.

Biomarkers of Cerebral Glucose Metabolism and Neurodegeneration in Parkinson's Disease: A Cerebrospinal Fluid-Based Study

BACKGROUND

Several biomarkers have been evaluated in Parkinson's disease (PD); cerebrospinal fluid (CSF) levels of lactate may reflect cerebral metabolism function and CSF amyloid-β42 (Aβ42), total tau (t-tau) and phosphorylated tau (p-tau) concentrations may detect an underlying neurodegenerative process.

OBJECTIVE

CSF levels of lactate, Aβ42, t-tau, and p-tau were measured in patients with mild to moderate PD. CSF levels of dopamine (DA) and its metabolite 3,4-Dihydroxyphenylacetic acid (DOPAC) were also assessed, exploring their relations with the other CSF biomarkers.

METHODS

101 drug-naive PD patients and 60 controls were included. Participants underwent clinical assessments and CSF biomarker analysis. Patients were divided into subgroups according to their Hoehn & Yahr stage (PD-1, PD-2, PD-3).

RESULTS

PD patients showed higher lactate levels (M = 1.91; p = 0.03) and lower Aβ42 (M = 595; p < 0.001) and DA levels (M = 0.32; p = 0.04) than controls (Mlactate = 1.72; MAβ42 = 837; MDA = 0.50), while no significant differences were found in t-tau, p-tau and DOPAC concentrations. Considering the subgroup analysis, PD-3 group had higher lactate (M = 2.12) and t-tau levels (M = 333) than both PD-1 (Mlactate = 1.75, p = 0.006; Mt - tau = 176, p = 0.008) and PD-2 groups (Mlactate = 1.91, p = 0.01; Mt - tau = 176, p = 0.03), as well as the controls (Mlactate = 1.72, p = 0.04; Mt - tau = 205, p = 0.04). PD-2 group showed higher lactate levels than PD-1 group (p = 0.04) and controls (p = 0.03). Finally, CSF lactate levels negatively correlated with DA (r = -0.42) and positively with t-tau CSF levels (r = 0.33).

CONCLUSION

This CSF-based study shows that lactate levels in PD correlated with both clinical disease progression and neurodegeneration biomarkers, such as tau proteins and DA. Further studies should explore the clinical potential of measuring CSF biomarkers for better understanding the role of brain energy metabolism in PD, for research and therapeutic options.

Platelet miRNA Biosignature Discriminates between Dementia with Lewy Bodies and Alzheimer's Disease

Dementia with Lewy bodies (DLB) is one of the most common causes of degenerative dementia, after Alzheimer's disease (AD), and presents pathological and clinical overlap with both AD and Parkinson's disease (PD). Consequently, only one in three DLB cases is diagnosed correctly. Platelets, previously related to neurodegeneration, contain microRNAs (miRNAs) whose analysis may provide disease biomarkers. Here, we profiled the whole platelet miRNA transcriptome from DLB patients and healthy controls. Differentially expressed miRNAs were further validated in three consecutive studies from 2017 to 2019 enrolling 162 individuals, including DLB, AD, and PD patients, and healthy controls. Results comprised a seven-miRNA biosignature, showing the highest diagnostic potential for the differentiation between DLB and AD. Additionally, compared to controls, two miRNAs were down-regulated in DLB, four miRNAs were up-regulated in AD, and two miRNAs were down-regulated in PD. Predictive target analysis identified three disease-specific clusters of pathways as a result of platelet-miRNA deregulation. Our cross-sectional study assesses the identification of a novel, highly specific and sensitive platelet-associated miRNA-based biosignature, which distinguishes DLB from AD.

N. BP, Mohamed Ibrahim N, Mustapha M. Aberrant Neurogliovascular Unit Dynamics in Cerebral Small Vessel Disease: A Rheological Clue to Vascular Parkinsonism

The distinctive anatomical assemble and functionally discrete multicellular cerebrovasculature dynamics confer varying rheological and blood-brain barrier permeabilities to preserve the integrity of cerebral white matter and its neural microenvironment. This homeostasis intricately involves the glymphatic system that manages the flow of interstitial solutes, metabolic waste, and clearance through the venous circulation. As a physiologically integrated neurogliovascular unit (NGVU) serving a particularly vulnerable cerebral white matter (from hypoxia, metabolic insults, infection, and inflammation), a likely insidious process over a lifetime could inflict microenvironment damages that may lead to pathological conditions. Two such conditions, cerebral small vessel disease (CSVD) and vascular parkinsonism (VaP), with poorly understood pathomechanisms, are frequently linked to this brain-wide NGVU. VaP is widely regarded as an atypical parkinsonism, described by cardinal motor manifestations and the presence of cerebrovascular disease, particularly white matter hyperintensities (WMHs) in the basal ganglia and subcortical region. WMHs, in turn, are a recognised imaging spectrum of CSVD manifestations, and in relation to disrupted NGVU, also include enlarged perivascular spaces. Here, in this narrative review, we present and discuss on recent findings that argue for plausible clues between CSVD and VaP by focusing on aberrant multicellular dynamics of a unique integrated NGVU-a crossroad of the immune-vascular-nervous system-which may also extend fresher insights into the elusive interplay between cerebral microvasculature and neurodegeneration, and the potential therapeutic targets.

Neurodegenerative movement disorders: An epigenetics perspective and promise for the future

Neurodegenerative movement disorders (NMDs) are age‐dependent disorders that are characterised by the degeneration and loss of neurons, typically accompanied by pathological accumulation of different protein aggregates in the brain, which lead to motor symptoms. NMDs include Parkinson's disease, multiple system atrophy, progressive supranuclear palsy, and Huntington's disease, among others. Epigenetic modifications are responsible for functional gene regulation during development, adult life and ageing and have progressively been implicated in complex diseases such as cancer and more recently in neurodegenerative diseases, such as NMDs. DNA methylation is by far the most widely studied epigenetic modification and consists of the reversible addition of a methyl group to the DNA without changing the DNA sequence. Although this research field is still in its infancy in relation to NMDs, an increasing number of studies point towards a role for DNA methylation in disease processes. This review addresses recent advances in epigenetic and epigenomic research in NMDs, with a focus on human brain DNA methylation studies. We discuss the current understanding of the DNA methylation changes underlying these disorders, the potential for use of these DNA modifications in peripheral tissues as biomarkers in early disease detection, classification and progression as well as a promising role in future disease management and therapy.

Development and Validation of a Prognostic Model for Cognitive Impairment in Parkinson's Disease With REM Sleep Behavior Disorder

The presentation and progression of Parkinson’s disease (PD) are not uniform, but the presence of rapid eye movement sleep behavior disorder (RBD) in PD patients may indicate a worse prognosis than isolated PD. Increasing evidence suggests that patients with comorbid PD and RBD (PD-RBD) are more likely to develop cognitive impairment (CI) than those with isolated PD; however, the predictors of CI in PD-RBD patients are not well understood. This study aimed to develop a prognostic model for predicting mild cognitive impairment (MCI) in PD-RBD patients. The data of PD-RBD patients were extracted from the Parkinson’s Progression Markers Initiative study (PPMI), and the sample was randomly divided into a training set (n = 96) and a validation set (n = 24). PD-MCI as defined by the level II Movement Disorder Society (MDS) diagnostic criteria was the outcome of interest. The demographic features, clinical assessments, dopamine transporter (DAT) imaging data, cerebrospinal fluid (CSF) analyses and genetic data of PD patients were considered candidate predictors. We found that performance on the University of Pennsylvania Smell Identification Test (UPSIT), the mean signal and asymmetry index of the putamen on DAT imaging, p-tau/α-syn and p-tau in CSF, and rs55785911 genotype were predictors of PD-MCI in PD-RBD patients. A C-index of 0.81 was obtained with this model, and a C-index of 0.73 was obtained in the validation set. Favorable results of calibrations and decision curve analysis demonstrated the efficacy and feasibility of this model. In conclusion, we developed a prognostic model for predicting MCI in PD-RBD patients; the model displayed good discrimination and calibration and may be a convenient tool for clinical application. Larger samples and external validation sets are needed to validate this model.

Lewy Body Dementias: A Coin with Two Sides?

Lewy body dementias (LBDs) consist of dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD), which are clinically similar syndromes that share neuropathological findings with widespread cortical Lewy body deposition, often with a variable degree of concomitant Alzheimer pathology. The objective of this article is to provide an overview of the neuropathological and clinical features, current diagnostic criteria, biomarkers, and management of LBD. Literature research was performed using the PubMed database, and the most pertinent articles were read and are discussed in this paper. The diagnostic criteria for DLB have recently been updated, with the addition of indicative and supportive biomarker information. The time interval of dementia onset relative to parkinsonism remains the major distinction between DLB and PDD, underpinning controversy about whether they are the same illness in a different spectrum of the disease or two separate neurodegenerative disorders. The treatment for LBD is only symptomatic, but the expected progression and prognosis differ between the two entities. Diagnosis in prodromal stages should be of the utmost importance, because implementing early treatment might change the course of the illness if disease-modifying therapies are developed in the future. Thus, the identification of novel biomarkers constitutes an area of active research, with a special focus on α-synuclein markers.

CDKN2A Gene Expression as a Potential Aging Biomarker in Dogs

Describing evolutionary conserved physiological or molecular patterns, which can reliably mark the age of both model organisms and humans or predict the onset of age-related pathologies has become a priority in aging research. The age-related gene-expression changes of the Cyclin Dependent Kinase Inhibitor 2A (CDKN2A) gene have been well-documented in humans and rodents. However, data is lacking from other relevant species, including dogs. Therefore, we quantified the CDKN2A mRNA abundance in dogs of different ages, in four tissue types: the frontal cortex of the brain, temporal muscle, skin, and blood. We found a significant, positive correlation between CDKN2A relative expression values and age in the brain, muscle, and blood; however, no correlation was detected in the skin. The strongest correlation was detected in the brain tissue (CDKN2A/GAPDH: r = 0.757, p < 0.001), similarly to human findings, while the muscle and blood showed weaker, but significant correlation. Our results suggest that CDKN2A might be a potential blood-borne biomarker of aging in dogs, although the validation and optimization will require further, more focused research. Our current results also clearly demonstrate that the role of CDKN2A in aging is conserved in dogs, regarding both tissue specificity and a pivotal role of CDKN2A in brain aging.

α-Synuclein Heteromers in Red Blood Cells of Alzheimer's Disease and Lewy Body Dementia Patients

BACKGROUND

Red blood cells (RBCs) contain the majority of α-synuclein (α-syn) in blood, representing an interesting model for studying the peripheral pathological alterations proved in neurodegeneration.

OBJECTIVE

The current study aimed to investigate the diagnostic value of total α-syn, amyloid-β (Aβ1-42), tau, and their heteroaggregates in RBCs of Lewy body dementia (LBD) and Alzheimer's disease (AD) patients compared to healthy controls (HC).

METHODS

By the use of enzyme-linked immunosorbent assays, RBCs concentrations of total α-syn, Aβ1-42, tau, and their heteroaggregates (α-syn/Aβ1-42 and α-syn/tau) were measured in 27 individuals with LBD (Parkinson's disease dementia, n = 17; dementia with Lewy bodies, n = 10), 51 individuals with AD (AD dementia, n = 37; prodromal AD, n = 14), and HC (n = 60).

RESULTS

The total α-syn and tau concentrations as well as α-syn/tau heterodimers were significantly lower in the LBD group and the AD group compared with HC, whereas α-syn/Aβ1-42 concentrations were significantly lower in the AD dementia group only. RBC α-syn/tau heterodimers had a higher diagnostic accuracy for differentiating patients with LBD versus HC (AUROC = 0.80).

CONCLUSION

RBC α-syn heteromers may be useful for differentiating between neurodegenerative dementias (LBD and AD) and HC. In particular, RBC α-syn/tau heterodimers have demonstrated good diagnostic accuracy for differentiating LBD from HC. However, they are not consistently different between LBD and AD. Our findings also suggest that α-syn, Aβ1-42, and tau interact in vivo to promote the aggregation and accumulation of each other.

Expression Levels of an Alpha-Synuclein Transcript in Blood May Distinguish between Early Dementia with Lewy Bodies and Parkinson's Disease

Lewy body diseases (LBD) including dementia with Lewy bodies (DLB) and Parkinson disease (PD) are characterized by alpha-synuclein pathology. DLB is difficult to diagnose and peripheral biomarkers are urgently needed. Therefore, we analyzed the expression of five alpha-synuclein gene (SNCA) transcripts, SNCAtv1, SNCAtv2, SNCAtv3, SNCA126, and SNCA112, in 45 LBD and control temporal cortex samples and in the blood of 72 DLB, 59 PD, and 54 control subjects. The results revealed overexpression of SNCAtv1 and SNCA112 in DLB, and SNCAtv2 in PD temporal cortices. In DLB blood, diminution of all SNCA transcripts was observed. SNCAtv1 and SNCAtv2 were diminished in PD with disease onset before 70 years. SNCAtv3, driven by its own promoter, showed opposite expression in early DLB and PD, suggesting that its amount may be an early, DLB specific biomarker. Correlation between blood transcript levels and disease duration was positive in DLB and negative in PD, possibly reflecting differences in brain alpha-synuclein aggregation rates associated with differences in disease courses. In conclusion, SNCA transcripts showed a disease-specific increase in the brain and were diminished in blood of LBD patients. SNCAtv3 expression was decreased in early DLB and increased in early PD and could be a biomarker for early DLB diagnosis.

Plasma Phospho-Tau Identifies Alzheimer's Co-Pathology in Patients with Lewy Body Disease

BACKGROUND

Alzheimer's disease co-pathology is common in dementia with Lewy bodies and Parkinson's disease with dementia (Lewy body disease) and can reliably be detected with positron emission tomography (PET) or cerebrospinal fluid (CSF) biomarkers. Recently developed blood biomarkers are more accessible and less expensive alternatives.

OBJECTIVE

To investigate if plasma phospho-tau217 and phospho-tau181 can detect Alzheimer's pathology in Lewy body disease with dementia.

METHODS

In this cross-sectional study we investigated plasma phospho-tau217 and phospho-tau181 in 35 patients with Lewy body disease with dementia. Patients underwent tau-PET imaging (¹⁸ F-RO948).

RESULTS

Plasma phospho-tau217 correlated with plasma phospho-tau181, CSF phospho-tau217 (r_s = 0.68, P < 0.001), and negatively with CSF β-amyloid_42/40 (r_s = -0.52, P = 0.001). Plasma phospho-tau217 and phospho-tau181 correlated with tau-PET signal in the temporal cortex (r_s  > 0.56, P < 0.001) and predicted abnormal tau-PET status and β-amyloid status (area under the curve > 0.78 and > 0.81, respectively).

CONCLUSION

Plasma phospho-tau might be a useful marker for Alzheimer's co-pathology in Lewy body disease with dementia. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Mounting evidence of FKBP12 implication in neurodegeneration

Intrinsically disordered proteins, such as tau or α-synuclein, have long been associated with a dysfunctional role in neurodegenerative diseases. In Alzheimer's and Parkinson's' diseases, these proteins, sharing a common chemical-physical pattern with alternating hydrophobic and hydrophilic domains rich in prolines, abnormally aggregate in tangles in the brain leading to progressive loss of neurons. In this review, we present an overview linking the studies on the implication of the peptidyl-prolyl isomerase domain of immunophilins, and notably FKBP12, to a variety of neurodegenerative diseases, focusing on the molecular origin of such a role. The involvement of FKBP12 dysregulation in the aberrant aggregation of disordered proteins pinpoints this protein as a possible therapeutic target and, at the same time, as a predictive biomarker for early diagnosis in neurodegeneration, calling for the development of reliable, fast and cost-effective detection methods in body fluids for community-based screening campaigns.

Fluid Candidate Biomarkers for Alzheimer's Disease: A Precision Medicine Approach

A plethora of dynamic pathophysiological mechanisms underpins highly heterogeneous phenotypes in the field of dementia, particularly in Alzheimer's disease (AD). In such a faceted scenario, a biomarker-guided approach, through the implementation of specific fluid biomarkers individually reflecting distinct molecular pathways in the brain, may help establish a proper clinical diagnosis, even in its preclinical stages. Recently, ultrasensitive assays may detect different neurodegenerative mechanisms in blood earlier. ß-amyloid (Aß) peptides, phosphorylated-tau (p-tau), and neurofilament light chain (NFL) measured in blood are gaining momentum as candidate biomarkers for AD. P-tau is currently the more convincing plasma biomarker for the diagnostic workup of AD. The clinical role of plasma Aβ peptides should be better elucidated with further studies that also compare the accuracy of the different ultrasensitive techniques. Blood NFL is promising as a proxy of neurodegeneration process tout court. Protein misfolding amplification assays can accurately detect α-synuclein in cerebrospinal fluid (CSF), thus representing advancement in the pathologic stratification of AD. In CSF, neurogranin and YKL-40 are further candidate biomarkers tracking synaptic disruption and neuroinflammation, which are additional key pathophysiological pathways related to AD genesis. Advanced statistical analysis using clinical scores and biomarker data to bring together individuals with AD from large heterogeneous cohorts into consistent clusters may promote the discovery of pathophysiological causes and detection of tailored treatments.

CSF and Blood Biomarkers in Neuroinflammatory and Neurodegenerative Diseases: Implications for Treatment

Neuroinflammatory and neurodegenerative diseases are characterized by the interplay of a number of molecular pathways that can be assessed through biofluids, especially cerebrospinal fluid and blood. Accordingly, the definition and classification of these disorders will move from clinical and pathological to biological criteria. The consequences of this biomarker-based diagnostic and prognostic approach are highly relevant to the field of drug development. Indeed, in view of the availability of disease-modifying drugs, fluid biomarkers offer a unique opportunity for improving the quality and applicability of results from clinical trials. Herein, we discuss the benefits of using fluid biomarkers for patient stratification, target engagement, and outcome assessment, as well as the most recent developments in neuroinflammatory and neurodegenerative diseases.

Increased Noradrenaline as an Additional Cerebrospinal Fluid Biomarker in PSP-Like Parkinsonism

Academic centers utilize sequential clinical and neuroimaging assessments, including morphometric ratios, to obtain an unequivocal diagnosis of the non-synucleinopathic forms of Parkinsonism, such as progressive supranuclear palsy (PSP), however, a 1-2 year follow-up is required. The on-going long-lasting trials using anti-tau antibodies for PSP patients might therefore be biased by the incorrect enrollment of Parkinson's disease (PD) patients manifesting early axial signs. This perspective study aimed at achieving two major goals: first, to summarize the established biomarker candidates found in cerebrospinal fluid (CSF) in probable PSP patients, including low p-tau and altered neurofilaments. Second, we share our recent data, from CSF samples of well-selected PSP subjects, attributable to both main variants (and revisited in light of MDS criteria), who were followed for 1 year before and 2 years after lumbar puncture. We found a significantly high level of noradrenaline (NE) in these patients, similar to controls, when compared to PD patients. In contrast, CSF samples, in PD, showed a significant reduction in CSF NE and its major metabolite, which confirmed that PD is a multi-system disease involving several endogenous pathways. The NE axis impairments were prominent in PSP featuring worse NPI. It might represent a counterpart to the early and peculiar psycho-pathological profiles that are observed in tauopathies. In conclusion, we highlight that CSF biomarkers, which are easy to collect, can provide rapid insights as diagnostic tools. Early alterations in endogenous NE machinery in atypical Parkinsonism may represent a specific risk trait in forms characterized by a worse prognosis.

Disentangling the Amyloid Pathways: A Mechanistic Approach to Etiology

Amyloids are fibrillar protein aggregates associated with diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), type II diabetes and Creutzfeldt-Jakob disease. The process of amyloid polymerization involves three pathological protein transformations; from natively folded conformation to the cross-β conformation, from biophysically soluble to insoluble, and from biologically functional to non-functional. While amyloids share a similar cross-β conformation, the biophysical transformation can either take place spontaneously via a homogeneous nucleation mechanism (HON) or catalytically on an exogenous surface via a heterogeneous nucleation mechanism (HEN). Here, we postulate that the different nucleation pathways can serve as a mechanistic basis for an etiological classification of amyloidopathies, where hereditary forms generally follow the HON pathway, while sporadic forms follow seed-induced (prions) or surface-induced (including microbially induced) HEN pathways. Critically, the conformational and biophysical amyloid transformation results in loss-of-function (LOF) of the original natively folded and soluble protein. This LOF can, at least initially, be the mechanism of amyloid toxicity even before amyloid accumulation reaches toxic levels. By highlighting the important role of non-protein species in amyloid formation and LOF mechanisms of toxicity, we propose a generalized mechanistic framework that could help better understand the diverse etiology of amyloid diseases and offer new opportunities for therapeutic interventions, including replacement therapies.

Perivascular Unit: This Must Be the Place. The Anatomical Crossroad Between the Immune, Vascular and Nervous System

Most neurological disorders seemingly have heterogenous pathogenesis, with overlapping contribution of neuronal, immune and vascular mechanisms of brain injury. The perivascular space in the brain represents a crossroad where those mechanisms interact, as well as a key anatomical component of the recently discovered glymphatic pathway, which is considered to play a crucial role in the clearance of brain waste linked to neurodegenerative diseases. The pathological interplay between neuronal, immune and vascular factors can create an environment that promotes self-perpetration of mechanisms of brain injury across different neurological diseases, including those that are primarily thought of as neurodegenerative, neuroinflammatory or cerebrovascular. Changes of the perivascular space can be monitored in humans in vivo using magnetic resonance imaging (MRI). In the context of glymphatic clearance, MRI-visible enlarged perivascular spaces (EPVS) are considered to reflect glymphatic stasis secondary to the perivascular accumulation of brain debris, although they may also represent an adaptive mechanism of the glymphatic system to clear them. EPVS are also established correlates of dementia and cerebral small vessel disease (SVD) and are considered to reflect brain inflammatory activity. In this review, we describe the “perivascular unit” as a key anatomical and functional substrate for the interaction between neuronal, immune and vascular mechanisms of brain injury, which are shared across different neurological diseases. We will describe the main anatomical, physiological and pathological features of the perivascular unit, highlight potential substrates for the interplay between different noxae and summarize MRI studies of EPVS in cerebrovascular, neuroinflammatory and neurodegenerative disorders.

The path to biomarker-based diagnostic criteria for the spectrum of neurodegenerative diseases

Introduction: The postmortem examination still represents the reference standard for detecting the pathological nature of chronic neurodegenerative diseases (NDD). This approach displays intrinsic conceptual limitations since NDD represent a dynamic spectrum of partially overlapping phenotypes, shared pathomechanistic alterations that often give rise to mixed pathologies.Areas covered: We scrutinized the international clinical diagnostic criteria of NDD and the literature to provide a roadmap toward a biomarker-based classification of the NDD spectrum. A few pathophysiological biomarkers have been established for NDD. These are time-consuming, invasive, and not suitable for preclinical detection. Candidate screening biomarkers are gaining momentum. Blood neurofilament light-chain represents a robust first-line tool to detect neurodegeneration tout court and serum progranulin helps detect genetic frontotemporal dementia. Ultrasensitive assays and retinal scans may identify Aβ pathology early, in blood and the eye, respectively. Ultrasound also represents a minimally invasive option to investigate the substantia nigra. Protein misfolding amplification assays may accurately detect α-synuclein in biofluids.Expert opinion: Data-driven strategies using quantitative rather than categorical variables may be more reliable for quantification of contributions from pathophysiological mechanisms and their spatial-temporal evolution. A systems biology approach is suitable to untangle the dynamics triggering loss of proteostasis, driving neurodegeneration and clinical evolution.

DRD2 methylation to differentiate dementia with Lewy bodies from Parkinson's disease

OBJECTIVE

The aim was to clarify whether DRD2 methylation changes in leukocytes of dementia with Lewy bodies (DLB) or Parkinson's disease (PD) patients are seen and can be used to discriminate between them.

METHODS

Methylation rates were examined in 23 DLB subjects and 23 age- and sex-matched healthy controls and 37 PD patients and 37 age- and sex-matched healthy controls.

RESULTS

Significant DRD2 DNA methylation changes were found in leukocytes of DLB and PD patients compared with healthy subjects. Discriminant analysis between DLB and PD using seven CpG sites demonstrated sensitivity and specificity of 83.8% and 90.9%, respectively. None of the CpG sites were associated with sex, age, age of onset, disease duration, and any of the neuropsychological tests in DLB and PD patients.

CONCLUSION

This is the first report showing that DRD2 DNA methylation rates in leukocytes were increased in DLB patients and decreased in PD patients. These results may be an important step in understanding epigenetic mechanisms underlying DLB and PD pathogenesis and providing a novel biomarker for discriminating between them.

APP-derived peptides reflect neurodegeneration in frontotemporal dementia

Objective

We aimed to investigate the relationship between cerebrospinal fluid levels (CSF) of amyloid precursor protein (APP)‐derived peptides related to the amyloidogenic pathway, cortical thickness, neuropsychological performance, and cortical gene expression profiles in frontotemporal lobar degeneration (FTLD)‐related syndromes, Alzheimer’s disease (AD), and healthy controls.

Methods

We included 214 participants with CSF available recruited at two centers: 93 with FTLD‐related syndromes, 57 patients with AD, and 64 healthy controls. CSF levels of amyloid β (Aβ)1‐42, Aβ1‐40, Aβ1‐38, and soluble β fragment of APP (sAPPβ) were centrally analyzed. We compared CSF levels of APP‐derived peptides between groups and, we studied the correlation between CSF biomarkers, cortical thickness, and domain‐specific cognitive composites in each group. Then, we explored the relationship between cortical thickness, CSF levels of APP‐derived peptides, and regional gene expression profile using a brain‐wide regional gene expression data in combination with gene set enrichment analysis.

Results

The CSF levels of Aβ1‐40, Aβ1‐38, and sAPPβ were lower in the FTLD‐related syndromes group than in the AD and healthy controls group. CSF levels of all APP‐derived peptides showed a positive correlation with cortical thickness and the executive cognitive composite in the FTLD‐related syndromes group but not in the healthy control or AD groups. In the cortical regions where we observed a significant association between cortical thickness and CSF levels of APP‐derived peptides, we found a reduced expression of genes related to synaptic function.

Interpretation

APP‐derived peptides in CSF may reflect FTLD‐related neurodegeneration. This observation has important implications as Aβ1‐42 levels are considered an indirect biomarker of cerebral amyloidosis.

Diagnostic Criteria for Dementia with Lewy Bodies: Updates and Future Directions

The aim of this article is to describe the 2017 revised consensus criteria for the clinical diagnosis of dementia with Lewy bodies (DLB) with future directions for the diagnostic criteria. The criteria for the clinical diagnosis of probable and possible DLB were first published as the first consensus report in 1996 and were revised in the third consensus report in 2005. After discussion at the International DLB Conference in Fort Lauderdale, Florida, USA, in 2015, the International DLB Consortium published the fourth consensus report including the revised consensus criteria in 2017. The 2017 revised criteria clearly distinguish between clinical features and diagnostic biomarkers. Significant new information about previously reported aspects of DLB has been incorporated, with increased diagnostic weighting given to rapid eye movement (REM) sleep behavior disorder (RBD) and iodine-123-metaiodobenzylguanidine (MIBG) myocardial scintigraphy. Future directions include the development of the criteria for early diagnosis (prodromal DLB) and the establishment of new biomarkers that directly indicate Lewy-related pathology, including α-synuclein imaging, biopsies of peripheral tissues (skin, etc.) for the demonstration of α-synuclein deposition, and biochemical markers (cerebrospinal fluid/blood), as well as the pathological evaluation of the sensitivity and specificity of the 2017 revised diagnostic criteria. In conclusion, the revised consensus criteria for the clinical diagnosis of DLB were reported with the incorporation of new information about DLB in 2017. Future directions include the development of the criteria for early diagnosis and the establishment of biomarkers directly indicative of Lewy-related pathology.

Alzheimer's disease and other neurodegenerative dementias in comorbidity: A clinical and neuropathological overview

Neuropathological diagnostic criteria of neurodegenerative disorders are based on the presence of specific inclusions in a specific area of brain tissue that correlate with clinical manifestations. Concomitant neurodegenerative disorders correspond to a combination of two (or more) different fully developed diseases in the same patient. Concomitant neurodegenerative pathology represents the presence of definite neurodegeneration and deposits of pathological proteins specific for another disease, which is not, however, fully developed. Very frequent overlaps include Alzheimer's disease and alpha-synuclein inclusions. Nevertheless, careful neuropathological investigations reveal an increasing frequency of different co-pathologies in examined brains. In Alzheimer's disease, protein TDP-43 may co-aggregate, but it is not clear whether this is atypical isolated Alzheimer's disease or overlap of Alzheimer's disease with early frontotemporal lobar degeneration. Comorbidities of Alzheimer's disease and tauopathies are relatively rare. A combination of vascular pathology with primary neurodegeneration (mostly Alzheimer's disease or dementia with Lewy bodies) is historically called mixed dementia. Overlap of different neuropathologically confirmed neurodegenerations could lead to atypical and unusual clinical presentations and may be responsible for faster disease progression. Several CSF biomarkers have been evaluated for their utility in diagnostic processes in different neurodegenerative dementias; however, evidence regarding their role in neurodegenerative overlaps is still limited.

Pharmacological targeting of α-synuclein and TPPP/p25 in Parkinson's disease: challenges and opportunities in a Nutshell

With the aging of population, neurological disorders, and especially disorders involving defects in protein conformation (also known as proteopathies) pose a serious socio-economic problem. So far there is no effective treatment for most proteopathies, including Parkinson's disease (PD). The mechanism underlying PD pathogenesis is largely unknown, and the hallmark proteins, α-synuclein (SYN) and tubulin polymerization promoting protein (TPPP/p25) are challenging drug targets. These proteins are intrinsically disordered with high conformational plasticity, and have diverse physiological and pathological functions. In the healthy brain, SYN and TPPP/p25 occur in neurons and oligodendrocytes, respectively; however, in PD and multiple system atrophy, they are co-enriched and co-localized in both cell types, thereby marking pathogenesis. Although large inclusions appear at a late disease stage, small, soluble assemblies of SYN promoted by TPPP/p25 are pathogenic. In the light of these issues, we established a new innovative strategy for the validation of a specific drug target based upon the identification of contact surfaces of the pathological SYN-TPPP/p25 complex that may lead to the development of peptidomimetic foldamers suitable for pharmaceutical intervention.