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BACKGROUND: The gut microbiome is a potentially modifiable factor in Alzheimer's disease (AD); however, understanding of its composition and function regarding AD pathology is limited. METHODS: Shallow-shotgun metagenomic data was used to analyze fecal microbiome from participants enrolled in the Wisconsin Microbiome in Alzheimer's Risk Study, leveraging clinical data and cerebrospinal fluid (CSF) biomarkers. Differential abundance and ordinary least squares regression analyses were performed to find differentially abundant gut microbiome features and their associations with CSF biomarkers of AD and related pathologies. RESULTS: Gut microbiome composition and function differed between people with AD and cognitively unimpaired individuals. The compositional difference was replicated in an independent cohort. Differentially abundant gut microbiome features were associated with CSF biomarkers of AD and related pathologies. DISCUSSION: These findings enhance our understanding of alterations in gut microbial composition and function in AD, and suggest that gut microbes and their pathways are linked to AD pathology.
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Plasma biomarkers of dementia, including phosphorylated tau (p-tau217), offer promise as tools for diagnosis, stratification for clinical trials, monitoring disease progression, and assessing the success of interventions in those living with Alzheimer's disease. However, currently, it is unknown whether these dementia biomarker levels vary with the time of day, which could have implications for their clinical value. In two protocols, we studied 38 participants (70.8 ± 7.6 years; mean ± SD) in a 27-h laboratory protocol with either two samples taken 12 h apart or 3-hourly blood sampling for 24 h in the presence of a sleep-wake cycle. The study population comprised people living with mild Alzheimer's disease (PLWA, n = 8), partners/caregivers of PLWA (n = 6) and cognitively intact older adults (n = 24). Single-molecule array technology was used to measure phosphorylated tau (p-tau217) (ALZpath), amyloid-beta 40 (Aß40), amyloid-beta 42 (Aß42), glial fibrillary acidic protein, and neurofilament light (NfL) (Neuro 4-Plex E). Analysis with a linear mixed model (SAS, PROC MIXED) revealed a significant effect of time of day for p-tau217, Aß40, Aß42, and NfL, and a significant effect of participant group for p-tau217. For p-tau217, the lowest levels were observed in the morning upon waking and the highest values in the afternoon/early evening. The magnitude of the diurnal variation for p-tau217 was similar to the reported increase in p-tau217 over one year in amyloid-ß-positive mild cognitively impaired people. Currently, the factors driving this diurnal variation are unknown and could be related to sleep, circadian mechanisms, activity, posture, or meals. Overall, this work implies that the time of day of sample collection may be relevant in the implementation and interpretation of plasma biomarkers in dementia research and care.
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Enfermedad de Alzheimer , Péptidos beta-Amiloides , Biomarcadores , Proteínas tau , Humanos , Proteínas tau/sangre , Femenino , Masculino , Anciano , Biomarcadores/sangre , Péptidos beta-Amiloides/sangre , Enfermedad de Alzheimer/sangre , Enfermedad de Alzheimer/diagnóstico , Fosforilación , Ritmo Circadiano/fisiología , Persona de Mediana Edad , Fragmentos de Péptidos/sangre , Proteínas de Neurofilamentos/sangre , Anciano de 80 o más Años , Demencia/sangre , Demencia/diagnóstico , Sueño/fisiología , Cuidadores , Proteína Ácida Fibrilar de la GlíaRESUMEN
Acetylcholine (ACh) is a critical neurotransmitter influencing various neurophysiological functions. Despite its significance, quantitative methods with adequate spatiotemporal resolution for recording a single exocytotic ACh efflux are lacking. In this study, we introduce an ultrafast amperometric ACh biosensor that enables 50 kHz electrochemical recording of spontaneous single exocytosis events at axon terminals of differentiated cholinergic human SH-SY5Y neuroblastoma cells with sub-millisecond temporal resolution. Characterization of the recorded amperometric traces revealed seven distinct current spike types, each displaying variations in shape, time scale, and ACh quantities released. This finding suggests that exocytotic release is governed by complex fusion pore dynamics in these cells. The absolute number of ACh molecules released during exocytosis was quantified by calibrating the sensor through the electroanalysis of liposomes preloaded with varying ACh concentrations. Notably, the largest quantal release involving approximately 8000 ACh molecules likely represents full exocytosis, while a smaller release of 5000 ACh molecules may indicate partial exocytosis. Following a local administration of bafilomycin A1, a V-ATPase inhibitor, the cholinergic cells exhibited both a larger quantity of ACh released and a higher frequency of exocytosis events. Therefore, this ACh sensor provides a means to monitor minute amounts of ACh and investigate regulatory release mechanisms at the single-cell level, which is vital for understanding healthy brain function and pathologies and optimizing drug treatment for disorders.
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Background: Blood-based biomarkers offer a promising, less invasive, and more cost-effective alternative for Alzheimer's disease screening compared to cerebrospinal fluid or imaging biomarkers. However, they have been extensively studied only in memory clinic-based cohorts. We aimed to validate them in a more heterogeneous, older patient population from primary care. Methods: We measured plasma Aß42/Aß40, P-tau181, NfL, and GFAP in 1007 individuals without dementia, aged 79-94 years, from the longitudinal, primary care-based German AgeCoDe study. We assessed the association with cognitive decline, disease progression, and the capacity to predict future dementia of the Alzheimer's type (DAT). We also evaluated biomarker dynamics in 305 individuals with a follow-up sample (â¼8 years later). Findings: Higher levels of P-tau181 (HR = 1.32 [95% CI: 1.17-1.51]), NfL (HR = 1.19 [95% CI: 1.03-1.36]), and GFAP (HR = 1.36 [95% CI: 1.22-1.52]), and a lower Aß42/Aß40 ratio (HR = 0.80 [95% CI: 0.68-0.95]) were associated with an increased risk of progressing to clinically-diagnosed DAT. Additionally, higher levels of P-tau181 (ß = -0.49 [95% CI: -0.71 to 0.26]), NfL (ß = -0.29 [95% CI: -0.52 to 0.06]), and GFAP (ß = -0.60 [95% CI: -0.83 to 0.38]) were linked to faster cognitive decline. A two-step DAT prediction strategy combining initial MMSE with biomarkers improved the identification of individuals in the prodromal stage for potential treatment eligibility. Biomarker levels changed over time, with increases in P-tau181 (ß = 0.19 [95% CI: 0.14-0.25]), NfL (ß = 2.88 [95% CI: 2.18-3.59]), and GFAP (ß = 8.23 [95% CI: 6.71-9.75]). NfL (ß = 2.47 [95% CI: 1.04-3.89]) and GFAP (ß = 4.45 [95% CI: 1.38-7.51]) exhibited a faster increase in individuals progressing to DAT. Interpretation: Evaluating plasma biomarkers, alongside brief cognitive assessments, might enhance the precision of risk assessment for DAT progression in primary care. Funding: Alzheimer Forschung Initiative, Bundesministerium für Bildung und Forschung.
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BACKGROUND: Phosphorylated tau (p-tau) is a specific blood biomarker for Alzheimer's disease (AD) pathology. Multiple p-tau biomarkers on several analytical platforms are poised for clinical use. The Alzheimer's Association Global Biomarker Standardisation Consortium plasma phospho-tau Round Robin study engaged assay developers in a blinded case-control study on plasma p-tau, aiming to learn which assays provide the largest fold-changes in AD compared to non-AD, have the strongest relationship between plasma and cerebrospinal fluid (CSF), and show the most consistent relationships between methods (commutability) in measuring both patient samples and candidate reference materials (CRM). METHODS: Thirty-three different p-tau biomarker assays, built on eight different analytical platforms, were used to quantify paired plasma and CSF samples from 40 participants. AD biomarker status was categorised as "AD pathology" (n=25) and "non-AD pathology" (n=15) by CSF Aß42/Aß40 (US-FDA; CE-IVDR) and p-tau181 (CE-IVDR) methods. The commutability of four CRM, at three concentrations, was assessed across assays. FINDINGS: Plasma p-tau217 consistently demonstrated higher fold-changes between AD and non-AD pathology groups, compared to other p-tau epitopes. Fujirebio LUMIPULSE G, UGOT IPMS, and Lilly MSD p-tau217 assays provided the highest median fold-changes. In CSF, p-tau217 assays also performed best, and exhibited substantially larger fold-changes than their plasma counterparts, despite similar diagnostic performance. P-tau217 showed the strongest correlations between plasma assays (rho=0.81 to 0.97). Plasma p-tau levels were weakly-to-moderately correlated with CSF p-tau, and correlations were non-significant within the AD group alone. The evaluated CRM were not commutable across assays. INTERPRETATION: Plasma p-tau217 measures had larger fold-changes and discriminative accuracies for detecting AD pathology, and better agreement across platforms than other plasma p-tau variants. Plasma and CSF markers of p-tau, measured by immunoassays, are not substantially correlated, questioning the interchangeability of their continuous relationship. Further work is warranted to understand the pathophysiology underlying this dissociation, and to develop suitable reference materials facilitating cross-assay standardisation. FUNDING: Alzheimer's Association (#ADSF-24-1284328-C).
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Cortisol dysregulation, neuroinflammation, and cerebrovascular dysfunction are biological processes that have been separately shown to be affected in Alzheimer's disease (AD). Here, we aimed to identify biomarker signatures reflecting these pathways in 108 memory clinic patients with subjective cognitive decline (SCD, N = 40), mild cognitive impairment (MCI, N = 39), and AD (N = 29). Participants were from the well-characterized Cortisol and Stress in Alzheimer's Disease (Co-STAR) cohort, recruited at Karolinska University Hospital. Salivary diurnal cortisol measures and 41 CSF proteins were analyzed. Principal component analysis was applied to identify combined biosignatures related to AD pathology, synaptic loss, and neuropsychological assessments, in linear regressions adjusted for confounders, such as age, sex, education and diagnosis. We found increased CSF levels of C-reactive protein (CRP), interferon γ-inducible protein (IP-10), thymus and activation-regulated chemokine (TARC), intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) in MCI patients. Further, markers of cortisol dysregulation (flattened salivary cortisol awakening response and flattened cortisol slope) correlated with increased levels of placental growth factor (PlGF), IP-10, and chitinase 3-like 1 (YKL-40) in the total cohort. A biosignature composed of cortisol awakening response, cortisol slope, and CSF IL-6 was downregulated in AD patients. Moreover, biomarker signatures reflecting overlapping pathophysiological processes of neuroinflammation and vascular injury were associated with AD pathology, synaptic loss, and worsened processing speed. Our findings suggest an early dysregulation of immune and cerebrovascular processes during the MCI stage and provide insights into the interrelationship of chronic stress and neuroinflammation in AD.
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Enfermedad de Alzheimer , Biomarcadores , Trastornos Cerebrovasculares , Disfunción Cognitiva , Hidrocortisona , Saliva , Humanos , Femenino , Masculino , Hidrocortisona/metabolismo , Biomarcadores/líquido cefalorraquídeo , Biomarcadores/metabolismo , Anciano , Disfunción Cognitiva/líquido cefalorraquídeo , Disfunción Cognitiva/metabolismo , Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/líquido cefalorraquídeo , Persona de Mediana Edad , Saliva/química , Saliva/metabolismo , Trastornos Cerebrovasculares/metabolismo , Trastornos Cerebrovasculares/líquido cefalorraquídeo , Estudios de Cohortes , Ritmo Circadiano/fisiología , Enfermedades Neuroinflamatorias/líquido cefalorraquídeo , Proteína C-Reactiva/análisis , Proteína C-Reactiva/metabolismo , Molécula 1 de Adhesión Intercelular/metabolismo , Molécula 1 de Adhesión Celular Vascular/metabolismo , Pruebas Neuropsicológicas , Quimiocina CXCL10/líquido cefalorraquídeo , Quimiocina CXCL10/metabolismoRESUMEN
BACKGROUND: Dementia poses a significant global health challenge. Anthocyanins neutralize free radicals, modulate signaling pathways, inhibit pro-inflammatory genes, and suppress cytokine production and may thus have positive cognitive effects in people at increased risk of dementia. We aim to investigate the effects of purified anthocyanins on cognitive function in people at increased risk of dementia according to their inflammation status based on blood-based inflammatory biomarkers. METHODS: This is a secondary analysis of a 24-week randomized, double-blind, placebo-controlled trial. Cluster analysis was performed to categorize two groups based on their individual inflammatory biomarker profile using multiplex sandwich ELISA for the quantitative measurement of cytokines. Descriptive statistics and longitudinal models assessed cognitive outcomes. The primary comparison was the group difference at week 24 based on a modified intention-to-treat analysis. RESULTS: Cluster analysis revealed two distinct inflammatory biomarker profiles. In Cluster 1 (high levels of inflammation biomarkers), anthocyanin treatment showed a statistically significant improvement on cognitive function compared to placebo at 24 weeks. No significant differences were observed in Cluster 2 (low levels of inflammation biomarkers). The demographic characteristics, cognitive scores, and biomarker distributions were similar between treatment groups at baseline. However, cluster 1 exhibited higher BMI, diabetes prevalence, medication usage, and lower HDL cholesterol levels. CONCLUSION: Individuals with elevated levels of inflammation markers benefited from anthocyanin treatment to enhance cognitive performance, whereas those with lower levels did not. The anti-inflammatory and antioxidant properties of anthocyanins make them a promising intervention, and future prospective trials in people with increased inflammation are warranted.
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BACKGROUND: Elevated neurofilament light chain (NfL) levels are associated with worse prognosis in Guillain-Barré syndrome (GBS). Our objectives were to determine the utility of serum NfL (sNfL), cerebrospinal fluid (CSF)/serum NfL ratio and NfL index as prognostic and diagnostic biomarkers for GBS. METHODS: We measured NfL in serum and/or CSF obtained from 96 GBS patients between 1989 and 2014 in western Sweden. The sNfL Z-scores, NfL ratios and NfL indices were calculated. Outcome was determined with the GBS disability scale (GBSDS) at 3 and 12 months. NfL parameters in GBS were compared with healthy controls (HC), multiple sclerosis (MS), and amyotrophic lateral sclerosis (ALS). RESULTS: The sNfL Z-score was higher for GBSDS > 2 at 3 months (median [IQR], 3.5 ng/L [3.2-4.0], vs 2.6 [1.7-3.4], p = 0.008) and at 12 months (3.6 ng/L [3.5-3.8] vs 2.6 [1.8-3.5], p = 0.049). NfL ratio and index were not associated with outcome. The area under the curve (AUC) for sNfL Z-score was 0.76 (95% CI 0.58-0.93, p < 0.0001) for GBSDS > 2 at 3 months. NfL ratio and index were lower in GBS than HC, MS, and ALS. The AUC for the NfL ratio was 0.66 (95% CI 0.55-0.78, p = 0.0018) and for the NfL index 0.86 (95% CI 0.78-0.93, p < 0.0001). DISCUSSION: Our results confirm sNfL as prognostic biomarker for GBS and the precision was improved using the age-adjusted sNfL Z score. NfL index and Qalb are potential diagnostic biomarkers for GBS.
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INTRODUCTION: The prognostic role of plasma neurofilament light chain (NfL), phospho-tau, beta-amyloid, and GFAP is still debated in Parkinson's disease (PD). METHODS: Plasma p-tau181, p-tau231, Aß1-40, Aß1-42, GFAP, and NfL were measured by SIMOA in 136 PD with 2.9 + 1.7 years of follow-up and 76 controls. Differences in plasma levels between controls and PD and their correlation with clinical severity and progression rates were evaluated using linear regression analyses. RESULTS: Patients exhibited similar distribution of plasma biomarkers but higher P-tau181, P-tau231 and lower Aß1-42 compared with controls. NfL and GFAP correlated with baseline motor and non-motor severity measures. At follow-up, NfL emerged as the best predictor of progression with marginal effect of GFAP and p-tau181 adjusting for age, sex, disease duration, and baseline motor severity. CONCLUSION: The present findings confirmed plasma NfL as best predictor of progression in PD, with a marginal role of p-tau181 and GFAP.
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Accurate assessment of neurological disease through monitoring of biomarkers has been made possible using the antibody-based assays. But these assays suffer from expensive development of antibody probes, reliance on complicated equipments, and high maintenance costs. Here, using the novel reduced graphene oxide/polydopamine-molecularly imprinted polymer (rGO/PDA-MIP) as the probe layer, a robust electrochemical sensing platform is demonstrated for the ultrasensitive detection of glial fibrillary acidic protein (GFAP), a biomarker for a range of neurological diseases. A miniaturized integrated circuit readout system is developed to interface with the electrochemical sensor, which empowers it with the potential to be used as a point-of-care (POC) diagnostic tool in primary clinical settings. This innovative platform demonstrated good sensitivity, selectivity, and stability, with imprinting factor evaluated as 2.8. A record low limit-of-detection (LoD) is down to 754.5 ag mL-1, with a wide dynamic range from 1 to 106 fg mL-1. The sensing platform is validated through the analysis of GFAP in clinical plasma samples, yielding a recovery rate range of 81.6-108.8% compared to Single Molecule Array (Simoa). This cost-effective and user-friendly sensing platform holds the potential to be deployed in primary and resource-limited clinical settings for the assessment of neurological diseases.
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Aim of the project was to evaluate the technical and clinical validity of plasma Lumipulse p-tau, Aß42 and Aß40 species and their correlation with CSF core Alzheimer's Disease (AD) markers; a method comparison with SIMOA was also performed. One-hundred-thirthy-three participants, namely 55 A+T+N+ AD, 28 Neurodegenerative disorders (NDD) and 50 controls were enrolled for the study. Lumipulse technical validity showed high stability for p-tau181, Aß42, and Aß40, with higher stability of p-tau to repeated freezing thaw cycles. p-tau181 levels detected by both techniques were higher in AD compared to both NDD/controls and exhibited a similar correlation with CSF p-tau levels, whereas Aß42 levels were slightly lower in AD with both methods. In the comparison between SIMOA and Lumipulse plasma markers, both techniques exhibited similar diagnostic accuracy for AD for p-tau181 (0.87; 95â¯%CI 0.81-0.94, vs 0.85; 95â¯%CI 0.78-0.93), whereas the best performance was reached by p-tau181/ Aß42 Lumipulse ratio (ROC AUC 0.915, 95â¯%CI 0.86-0.97). The study thus confirmed the construct validity of both Lumipulse and SIMOA techniques for the identification of CSF AD pattern in clinical settings.
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Enfermedad de Alzheimer , Péptidos beta-Amiloides , Biomarcadores , Proteínas tau , Enfermedad de Alzheimer/sangre , Enfermedad de Alzheimer/diagnóstico , Humanos , Proteínas tau/sangre , Proteínas tau/líquido cefalorraquídeo , Biomarcadores/sangre , Biomarcadores/líquido cefalorraquídeo , Péptidos beta-Amiloides/sangre , Péptidos beta-Amiloides/líquido cefalorraquídeo , Femenino , Masculino , Anciano , Persona de Mediana Edad , Fragmentos de Péptidos/sangre , Fragmentos de Péptidos/líquido cefalorraquídeo , Anciano de 80 o más AñosRESUMEN
In the context of the escalating global health challenge posed by Alzheimer's disease (AD), this comprehensive review considers the potential of melatonin in both preventive and therapeutic capacities. As a naturally occurring hormone and robust antioxidant, accumulating evidence suggests melatonin is a compelling candidate to consider in the context of AD-related pathologies. The review considers several mechanisms, including potential effects on amyloid-beta and pathologic tau burden, antioxidant defense, immune modulation, and regulation of circadian rhythms. Despite its promise, several gaps need to be addressed prior to clinical translation. These include conducting additional randomized clinical trials in patients with or at risk for AD dementia, determining optimal dosage and timing, and further determining potential side effects, particularly of long-term use. This review consolidates existing knowledge, identifies gaps, and suggests directions for future research to better understand the potential of melatonin for neuroprotection and disease mitigation within the landscape of AD.
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BACKGROUND AND PURPOSE: Chemotherapy-induced peripheral neuropathy (CIPN) is a troublesome side effect in patients exposed to taxanes in the treatment of cancer and may affect quality of life dramatically. Here we assessed whether serum levels of neurofilament light (NfL) and tau (two neuroaxonal injury biomarkers) and glial fibrillary acidic protein (GFAP, a biomarker for astrocytic activation) correlate with the development of CIPN in the adjuvant setting of early breast cancer. MATERIALS AND METHODS: Using ultrasensitive single molecule array technology, serum levels of NfL, GFAP, and tau were measured before and every 3 weeks in 10 women receiving adjuvant EC (epirubicin 90 mg/m² and cyclophosphamide 600 mg/m²) every 3 weeks × 3, followed by weekly paclitaxel 80 mg/m² × 9-12 weeks after surgery due to early breast cancer. CIPN was graded according to the NCI Common Terminology Criteria for Adverse Events (CTCAE v5.0) and the questionnaire EORTC QLQ CIPN-20. RESULTS: Serum levels of GFAP increased successively during cycles of EC. NfL increased instead in response to the treatment of paclitaxel. NfL and GFAP continued to rise throughout exposure of cumulatively higher doses of paclitaxel and were reduced 3 months after the end of chemotherapy. Serums levels of tau were marginally affected by exposure to chemotherapy. Women with worse symptoms of CIPN had higher concentrations of NfL than women with mild symptoms of CIPN. INTERPRETATION: NfL and GFAP are promising biomarkers to identify women at risk of developing CIPN. Larger prospective studies are now needed.
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Biomarcadores , Neoplasias de la Mama , Epirrubicina , Proteína Ácida Fibrilar de la Glía , Proteínas de Neurofilamentos , Paclitaxel , Enfermedades del Sistema Nervioso Periférico , Proteínas tau , Humanos , Femenino , Enfermedades del Sistema Nervioso Periférico/inducido químicamente , Enfermedades del Sistema Nervioso Periférico/sangre , Enfermedades del Sistema Nervioso Periférico/diagnóstico , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/sangre , Proteínas de Neurofilamentos/sangre , Persona de Mediana Edad , Proteína Ácida Fibrilar de la Glía/sangre , Paclitaxel/efectos adversos , Paclitaxel/administración & dosificación , Proteínas tau/sangre , Adulto , Biomarcadores/sangre , Epirrubicina/efectos adversos , Epirrubicina/administración & dosificación , Astrocitos/efectos de los fármacos , Astrocitos/patología , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Ciclofosfamida/efectos adversos , Ciclofosfamida/administración & dosificación , Anciano , Quimioterapia Adyuvante/efectos adversosRESUMEN
BACKGROUND: Mechanisms underlying neurodegeneration in multiple sclerosis (MS) remain poorly understood but mostly implicate molecular pathways that are not unique to MS. Recently detected tau seeding activity in MS brain tissues corroborates previous neuropathological reports of hyperphosphorylated tau (p-tau) accumulation in secondary and primary progressive MS (PPMS). We aimed to investigate whether aberrant tau phosphorylation can be detected in the cerebrospinal fluid (CSF) of MS patients by using novel ultrasensitive immunoassays for different p-tau biomarkers. METHODS: CSF samples of patients with MS (n = 55) and non-inflammatory neurological disorders (NIND, n = 31) were analysed with in-house Single molecule array (Simoa) assays targeting different tau phosphorylation sites (p-tau181, p-tau212, p-tau217 and p-tau231). Additionally, neurofilament light (NFL) and glial fibrillary acidic protein (GFAP) were measured with a multiplexed Simoa assay. Patients were diagnosed with clinically isolated syndrome (CIS, n = 10), relapsing-remitting MS (RRMS, n = 21) and PPMS (n = 24) according to the 2017 McDonald criteria and had MRI, EDSS and basic CSF analysis performed at the time of diagnosis. RESULTS: Patients with progressive disease course had between 1.4-fold (p-tau217) and 2.2-fold (p-tau212) higher p-tau levels than relapsing MS patients (PPMS compared with CIS + RRMS, p < 0.001 for p-tau181, p-tau212, p-tau231 and p = 0.042 for p-tau217). P-tau biomarkers were associated with disease duration (ρ=0.466-0.622, p < 0.0001), age (ρ=0.318-0.485, p < 0.02, all but p-tau217) and EDSS at diagnosis and follow-up (ρ=0.309-0.440, p < 0.02). In addition, p-tau biomarkers correlated with GFAP (ρ=0.517-0.719, p ≤ 0.0001) but not with the albumin quotient, CSF cell count or NFL. Patients with higher MRI lesion load also had higher p-tau levels p ≤ 0.01 (<10 vs. ≥ 10 lesions, all p ≤ 0.01). CONCLUSION: CSF concentrations of novel p-tau biomarkers point to a higher degree of tau phosphorylation in PPMS than in RRMS. Associations with age, disease duration and EDSS suggest this process increases with disease severity; however, replication of these results in larger cohorts is needed to further clarify the relevance of altered tau phosphorylation throughout the disease course in MS.
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Biomarcadores , Progresión de la Enfermedad , Proteínas tau , Humanos , Proteínas tau/líquido cefalorraquídeo , Femenino , Masculino , Persona de Mediana Edad , Fosforilación , Adulto , Biomarcadores/líquido cefalorraquídeo , Proteínas de Neurofilamentos/líquido cefalorraquídeo , Esclerosis Múltiple Crónica Progresiva/líquido cefalorraquídeo , Esclerosis Múltiple Crónica Progresiva/diagnóstico , Proteína Ácida Fibrilar de la Glía/líquido cefalorraquídeo , Esclerosis Múltiple Recurrente-Remitente/líquido cefalorraquídeo , Esclerosis Múltiple Recurrente-Remitente/diagnóstico por imagen , Esclerosis Múltiple Recurrente-Remitente/diagnóstico , Esclerosis Múltiple Recurrente-Remitente/metabolismo , Esclerosis Múltiple/líquido cefalorraquídeo , Esclerosis Múltiple/diagnóstico , Esclerosis Múltiple/metabolismoRESUMEN
Previous studies have shown that glial and neuronal changes may trigger synaptic dysfunction in Alzheimer's disease(AD). However, the link between glial and neuronal markers and synaptic abnormalities in the living brain is poorly understood. Here, we investigated the association between biomarkers of astrocyte and microglial reactivity and synaptic dysfunction in 478 individuals across the aging and AD spectrum from two cohorts with available CSF measures of amyloid-ß(Aß), phosphorylated tau(pTau181), astrocyte reactivity(GFAP), microglial activation(sTREM2), and synaptic biomarkers(GAP43 and neurogranin). Elevated CSF GFAP levels were linked to presynaptic and postsynaptic dysfunction, regardless of cognitive status or Aß presence. CSF sTREM2 levels were associated with presynaptic biomarkers in cognitively unimpaired and impaired Aß + individuals and postsynaptic biomarkers in cognitively impaired Aß + individuals. Notably, CSF pTau181 levels mediated all associations between GFAP or sTREM2 levels and synaptic dysfunction biomarkers. These results suggest that neuronal-related synaptic biomarkers could be used in clinical trials targeting glial reactivity in AD.
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INTRODUCTION: We investigated blood DNA methylation patterns associated with 15 well-established cerebrospinal fluid (CSF) biomarkers of Alzheimer's disease (AD) pathophysiology, neuroinflammation, and neurodegeneration. METHODS: We assessed DNA methylation in 885 blood samples from the European Medical Information Framework for Alzheimer's Disease (EMIF-AD) study using the EPIC array. RESULTS: We identified Bonferroni-significant differential methylation associated with CSF YKL-40 (five loci) and neurofilament light chain (NfL; seven loci) levels, with two of the loci associated with CSF YKL-40 levels correlating with plasma YKL-40 levels. A co-localization analysis showed shared genetic variants underlying YKL-40 DNA methylation and CSF protein levels, with evidence that DNA methylation mediates the association between genotype and protein levels. Weighted gene correlation network analysis identified two modules of co-methylated loci correlated with several amyloid measures and enriched in pathways associated with lipoproteins and development. DISCUSSION: We conducted the most comprehensive epigenome-wide association study (EWAS) of AD-relevant CSF biomarkers to date. Future work should explore the relationship between YKL-40 genotype, DNA methylation, and protein levels in the brain. HIGHLIGHTS: Blood DNA methylation was assessed in the EMIF-AD MBD study. Epigenome-wide association studies (EWASs) were performed for 15 Alzheimer's disease (AD)-relevant cerebrospinal fluid (CSF) biomarker measures. Five Bonferroni-significant loci were associated with YKL-40 levels and seven with neurofilament light chain (NfL). DNA methylation in YKL-40 co-localized with previously reported genetic variation. DNA methylation potentially mediates the effect of single-nucleotide polymorphisms (SNPs) in YKL-40 on CSF protein levels.
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INTRODUCTION: The established link between DNA methylation and pathophysiology of dementia, along with its potential role as a molecular mediator of lifestyle and environmental influences, positions blood-derived DNA methylation as a promising tool for early dementia risk detection. METHODS: In conjunction with an extensive array of machine learning techniques, we employed whole blood genome-wide DNA methylation data as a surrogate for 14 modifiable and non-modifiable factors in the assessment of dementia risk in independent dementia cohorts. RESULTS: We established a multivariate methylation risk score (MMRS) for identifying mild cognitive impairment cross-sectionally, independent of age and sex (P = 2.0 × 10-3). This score significantly predicted the prospective development of cognitive impairments in independent studies of Alzheimer's disease (hazard ratio for Rey's Auditory Verbal Learning Test (RAVLT)-Learning = 2.47) and Parkinson's disease (hazard ratio for MCI/dementia = 2.59). DISCUSSION: Our work shows the potential of employing blood-derived DNA methylation data in the assessment of dementia risk. HIGHLIGHTS: We used whole blood DNA methylation as a surrogate for 14 dementia risk factors. Created a multivariate methylation risk score for predicting cognitive impairment. Emphasized the role of machine learning and omics data in predicting dementia. The score predicts cognitive impairment development at the population level.
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Background: Synaptic dysfunction is closely associated with cognitive function in Alzheimer's disease (AD), and is present already in an early stage of the disease. Objective: Using serial cerebrospinal fluid (CSF) sampling, we aimed to investigate slopes of CSF synaptic proteins, and their relation with cognition along the AD continuum. Methods: We included subjects with subjective cognitive decline (SCD) or mild cognitive impairment (MCI) (nâ=â50 amyloid-ß+ [Aâ+], nâ=â50 A-) and 50 patients with AD dementia from the Amsterdam dementia cohort, with CSF at two time points (median[IQR] 2.1[1.4-2.7] years). We analyzed 17 synaptic proteins and neurofilament light (NfL). Using linear mixed models we assessed trajectories of protein levels, and associations with cognitive decline (repeated Mini-Mental State Examination). We used Cox regression models to assess predictive value of protein levels for progression to AD dementia. Results: At baseline most proteins showed increased levels in AD dementia compared to the other groups. In contrast NPTX2 levels were lower in AD dementia. Higher baseline levels of SNAP25, ß-syn, and 14-3-3 proteins were associated with faster cognitive decline (St.B[SE] -0.27[0.12] to -0.61[0.12]). Longitudinal analyses showed that SYT1 and NPTX levels decreased over time in AD dementia (st.B[SE] -0.10[0.04] to -0.15[0.05]) and SCD/MCI-A+ (St.B[SE] -0.07[0.03] to -0.12[0.03]), but not in SCD/MCI-A- (pinteractionâ<â0.05). Increase over time in NfL levels was associated with faster cognitive decline in AD dementia (St.B[SE] -1.75[0.58]), but not in the other groups (pinteractionâ<â0.05). Conclusions: CSF synaptic proteins showed different slopes over time, suggesting complex synaptic dynamics. High levels of especially SNAP-25 may have value for prediction of cognitive decline in early AD stages, while increase in NfL over time correlates better with cognitive decline in later stages.
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Enfermedad de Alzheimer , Péptidos beta-Amiloides , Biomarcadores , Disfunción Cognitiva , Progresión de la Enfermedad , Proteínas de Neurofilamentos , Humanos , Enfermedad de Alzheimer/líquido cefalorraquídeo , Enfermedad de Alzheimer/diagnóstico , Masculino , Femenino , Anciano , Biomarcadores/líquido cefalorraquídeo , Disfunción Cognitiva/líquido cefalorraquídeo , Proteínas de Neurofilamentos/líquido cefalorraquídeo , Péptidos beta-Amiloides/líquido cefalorraquídeo , Persona de Mediana Edad , Proteínas del Tejido Nervioso/líquido cefalorraquídeo , Sinapsis , Proteína 25 Asociada a Sinaptosomas/líquido cefalorraquídeo , Estudios de Cohortes , Proteína C-ReactivaRESUMEN
INTRODUCTION: In this study, we investigated biomarkers in a midlife, racially diverse, at-risk cohort to facilitate early identification and intervention. We examined neuroimaging measures, including resting state functional magnetic resonance imaging (fMRI), white matter hyperintensity vo (WMH), and hippocampal volumes, alongside cerebrospinal fluid (CSF) markers. METHODS: Our data set included 76 cognitively unimpaired, middle-aged, Black Americans (N = 29, F/M = 17/12) and Non-Hispanic White (N = 47, F/M = 27/20) individuals. We compared cerebrospinal fluid phosphorylated tau141 and amyloid beta (Aß)42 to fMRI default mode network (DMN) subnetwork connectivity, WMH volumes, and hippocampal volumes. RESULTS: Results revealed a significant race × Aß42 interaction in Black Americans: lower Aß42 was associated with reduced DMN connectivity and increased WMH volumes regions but not in non-Hispanic White individuals. DISCUSSION: Our findings suggest that precuneus DMN connectivity and temporal WMHs may be linked to Alzheimer's disease risk pathology during middle age, particularly in Black Americans. HIGHLIGHTS: Cerebrospinal fluid (CSF) amyloid beta (Aß)42 relates to precuneus functional connectivity in Black, but not White, Americans. Higher white matter hyperintensity volume relates to lower CSF Aß42 in Black Americans. Precuneus may be a hub for early Alzheimer's disease pathology changes detected by functional connectivity.