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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., (© 2024 The Author(s). Alzheimer's & Dementia published by Wiley Periodicals LLC on behalf of Alzheimer's Association.)

Objectives : While granulocyte colony-stimulating factor (G-CSF) has shown beneficial effects in experimental ischemic stroke (IS), these effects have not been reproduced clinically. Small-to-medium-sized observational studies have reported varying associations for G-CSF with stroke severity and post-stroke functional outcome, prompting their investigation in a larger study. Methods : Endogenous serum G-CSF (S-GCSF) was measured in the acute phase and after 3 months in patients with IS (N = 435; 36% females; mean age, 57 years) from the Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS). Stroke severity was scored according to the National Institutes of Health Stroke Scale (NIHSS), and the modified Rankin Scale (mRS) assessed functional outcomes at 3-month and 2-year post-stroke. Correlation and logistic regression analyses with confounder adjustments assessed the relationships.Results: The acute S-GCSF level was 23% higher than at 3-month post-stroke (p < 0.001). Acute G-CSF correlated weakly with stroke severity quintiles (r = 0.12, p = 0.013) and with high-sensitivity C-reactive protein (r = 0.29, p < 0.001). The association between S-GCSF (as quintiles, q) and poor functional outcome at 3 months (mRS 3-6; S-GCSF-q5 vs. S-GCSF-q1, age- and sex-adjusted odds ratio: 4.27, 95% confidence interval: 1.82-9.99; p = 0.001) withstood adjustment for cardiovascular risk factors and stroke subtype, but not additional correction for stroke severity. Post-stroke changes in S-GSCF and absolute 3-month S-GCSF were not associated with 3-month or 2-year functional outcomes.Discussion: Early post-stroke S-GCSF is increased in severe IS and associated with 3-month poor functional outcomes. The change in S-GCSF and the 3-month S-GCSF appear to be less-important, and S-GCSF likely reflects inflammation in large infarctions.

Introduction: Neurofilament light (NfL), chitinase-3-like protein 1 (YKL-40), and neurogranin (Ng) are biomarkers for Alzheimer's disease (AD) to monitor axonal damage, astroglial activation, and synaptic degeneration, respectively., Methods: We performed genome-wide association studies (GWAS) using DNA and cerebrospinal fluid (CSF) samples from the EMIF-AD Multimodal Biomarker Discovery study for discovery, and the Alzheimer's Disease Neuroimaging Initiative study for validation analyses. GWAS were performed for all three CSF biomarkers using linear regression models adjusting for relevant covariates., Results: We identify novel genome-wide significant associations between DNA variants in TMEM106B and CSF levels of NfL, and between CPOX and YKL-40. We confirm previous work suggesting that YKL-40 levels are associated with DNA variants in CHI3L1., Discussion: Our study provides important new insights into the genetic architecture underlying interindividual variation in three AD-related CSF biomarkers. In particular, our data shed light on the sequence of events regarding the initiation and progression of neuropathological processes relevant in AD., (© 2021 The Authors. Alzheimer's & Dementia published by Wiley Periodicals LLC on behalf of Alzheimer's Association.)

Introduction: This study sought to discover and replicate plasma proteomic biomarkers relating to Alzheimer's disease (AD) including both the "ATN" (amyloid/tau/neurodegeneration) diagnostic framework and clinical diagnosis., Methods: Plasma proteins from 972 subjects (372 controls, 409 mild cognitive impairment [MCI], and 191 AD) were measured using both SOMAscan and targeted assays, including 4001 and 25 proteins, respectively., Results: Protein co-expression network analysis of SOMAscan data revealed the relation between proteins and "N" varied across different neurodegeneration markers, indicating that the ATN variants are not interchangeable. Using hub proteins, age, and apolipoprotein E ε4 genotype discriminated AD from controls with an area under the curve (AUC) of 0.81 and MCI convertors from non-convertors with an AUC of 0.74. Targeted assays replicated the relation of four proteins with the ATN framework and clinical diagnosis., Discussion: Our study suggests that blood proteins can predict the presence of AD pathology as measured in the ATN framework as well as clinical diagnosis., (© 2021 the Alzheimer's Association.)

Objectives: The cause of ischemic stroke remains unknown, cryptogenic, in 25% of young and middle-aged patients. We hypothesized that if atherosclerosis is prominent in cryptogenic stroke, it would have a similar proinflammatory protein signature as large artery atherosclerosis (LAA) stroke., Materials & Methods: Blood was collected in the acute phase and after 3 months from cryptogenic (n = 162) and LAA (n = 73) stroke patients aged 18-69 years and once from age-matched controls (n = 235). Cryptogenic stroke was divided into Framingham Risk Score (FRS) quartiles to compare low and high risk of atherosclerosis. Plasma concentrations of 25 proteins were analyzed using a Luminex multiplex assay. The discriminating properties were assessed with discriminant analysis and C-statistics., Results: We identified proteins that separated cryptogenic and LAA stroke from controls (area under the curves, AUCs ≥ 0.85). For both subtypes, RANTES, IL-4, and IFN-γ contributed the most at both time points. These associations were independent of risk factors of atherosclerosis. We also identified proteins that separated cryptogenic strokes in the lowest quartile of FRS from those in the highest, and from LAA stroke (AUCs ≥ 0.76), and here eotaxin and MCP-1 contributed the most., Conclusions: The protein signature separating cases from controls was different from the signature separating cryptogenic stroke with low risk of atherosclerosis from those with high risk and from LAA stroke. This suggests that increased RANTES, IL-4, and IFN-γ in stroke may not be primarily related to atherosclerosis, whereas increased eotaxin and MCP-1 in cryptogenic stroke may be markers of occult atherosclerosis as the underlying cause., (© 2020 The Authors. Acta Neurologica Scandinavica published by John Wiley & Sons Ltd.)

Introduction: This study examines the utility of a multipanel of cerebrospinal fluid (CSF) biomarkers complementing Alzheimer's disease (AD) biomarkers in a clinical research sample. We compared biomarkers across groups defined by clinical diagnosis and pTau 181 /Aβ 42 status (+/-) and explored their value in predicting cognition., Methods: CSF biomarkers amyloid beta (Aβ) 42 , pTau 181 , tTau, Aβ 40 , neurogranin, neurofilament light (NfL), α-synuclein, glial fibrillary acidic protein (GFAP), chitinase-3-like protein 1 (YKL-40), soluble triggering receptor expressed on myeloid cells 2 (sTREM2), S100 calcium binding protein B (S100B), and interleukin 6 (IL6), were measured with the NeuroToolKit (NTK) for 720 adults ages 40 to 93 years (mean age = 63.9 years, standard deviation [SD] = 9.0; 50 with dementia; 54 with mild cognitive impairment [MCI], 616 unimpaired)., Results: Neurodegeneration and glial activation biomarkers were elevated in pTau 181 /Aβ 42 + MCI/dementia participants relative to all pTau 181 /Aβ 42 - participants. Neurodegeneration biomarkers increased with clinical severity among pTau 181 /Aβ 42 + participants and predicted worse cognitive performance. Glial activation biomarkers were unrelated to cognitive performance., Discussion: The NTK contains promising markers that improve the pathophysiological characterization of AD. Neurodegeneration biomarkers beyond tTau improved statistical prediction of cognition and disease stages., (© 2020 the Alzheimer's Association.)

Matrix metalloproteinases (MMPs) are extracellular enzymes involved in the degradation of extracellular matrix (ECM) proteins. Increased expression of MMPs have been described in traumatic brain injury (TBI) and may contribute to additional tissue injury and blood-brain barrier damage. The objectives of this study were to determine longitudinal changes in cerebrospinal fluid (CSF) concentrations of MMPs after acute TBI and in relation to clinical outcomes, with patients with idiopathic normal pressure hydrocephalus (iNPH) serving as a contrast group. The study included 33 TBI patients with ventricular CSF serially sampled, and 38 iNPH patients in the contrast group. Magnetic bead-based immunoassays were utilized to measure the concentrations of eight MMPs in ventricular human CSF. CSF concentrations of MMP-1, MMP-3 and MMP-10 were increased in TBI patients (at baseline) compared with the iNPH group (p < 0.001), while MMP-2, MMP-9 and MMP-12 did not differ between the groups. MMP-1, MMP-3 and MMP-10 concentrations decreased with time after trauma (p = 0.001-0.04). Increased concentrations of MMP-2 and MMP-10 in CSF at baseline were associated with an unfavourable TBI outcome (p = 0.002-0.02). Observed variable pattern of changes in MMP concentrations indicates that specific MMPs serve different roles in the pathophysiology following TBI, and are in turn associated with clinical outcomes.

Until relatively recently, a diagnosis of probable Alzheimer's disease (AD) and other neurodegenerative disorders was principally based on clinical presentation, with post-mortem examination remaining a gold standard for disease confirmation. This is in sharp contrast to other areas of medicine, where fluid biomarkers, such as troponin levels in myocardial infarction, form an integral part of the diagnostic and treatment criteria. There is a pressing need for such quantifiable and easily accessible tools in neurodegenerative diseases.In this paper, based on lectures given at the 2019 Biomarkers in Neurodegenerative Diseases Course, we provide an overview of a range of cerebrospinal fluid (CSF) and blood biomarkers in neurodegenerative disorders, including the 'core' AD biomarkers amyloid β (Aβ) and tau, as well as other disease-specific and general markers of neuroaxonal injury. We then highlight the main challenges in the field, and how those could be overcome with the aid of new methodological advances, such as assay automation, mass spectrometry and ultrasensitive immunoassays.As we hopefully move towards an era of disease-modifying treatments, reliable biomarkers will be essential to increase diagnostic accuracy, allow for earlier diagnosis, better participant selection and disease activity and treatment effect monitoring.

Stability of the cerebrospinal fluid (CSF) composition under different pre-analytical conditions is relevant for the diagnostic potential of biomarkers. Our aim was to examine the pre-analytical stability of promising CSF biomarkers that are currently evaluated for their discriminative use in various neurological diseases. Pooled CSF was aliquoted and experimentally exposed to delayed storage: 0, 1, 2, 4, 24, 72, or 168 h at 4 °C or room temperature (RT), or 1-4 months at -20 °C; or up to 7 freeze/thaw (f/t) cycles, before final storage at -80 °C. Eleven CSF biomarkers were screened using immunoassays, liquid chromatography, or enzymatic methods. Levels of neurogranin (truncP75), chitinase-3-like protein (YKL-40), beta-site amyloid precursor protein cleaving enzyme 1 (BACE1), acetylcholinesterase (AChE) enzymatic activity, theobromine, secreted protein acidic and rich in cysteine-like 1 (SPARCL-1) and homovanillic acid (HVA) levels were not affected by the applied storage conditions. 3-Methoxy-4-hydroxyphenylglycol (MHPG) levels linearly and strongly decreased after 4 h at RT (-10%) or 24 h at 4 °C (-27%), and with 6% after every f/t cycle. 5-Methyltetrahydrofolate (5-MTHF) (-29% after 1 week at RT) and 5-hydroxyindoleacetic acid levels (5-HIAA) (-16% after 1 week at RT) were reduced and 3,4-dihydroxyphenylacetic acid (DOPAC) levels (+22% after 1 week at RT) increased, but only after >24 h at RT. Ten out of eleven potential CSF novel biomarkers showed very limited change under common storage and f/t conditions, suggesting that these CSF biomarkers can be trustfully tested under the pre-analytical conditions present across different cohorts., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Introduction: We investigated relations between amyloid-β (Aβ) status, apolipoprotein E (APOE) ε4, and cognition, with cerebrospinal fluid markers of neurogranin (Ng), neurofilament light (NFL), YKL-40, and total tau (T-tau)., Methods: We included 770 individuals with normal cognition, mild cognitive impairment, and Alzheimer's disease (AD)-type dementia from the EMIF-AD Multimodal Biomarker Discovery study. We tested the association of Ng, NFL, YKL-40, and T-tau with Aβ status (Aβ- vs. Aβ+), clinical diagnosis APOE ε4 carriership, baseline cognition, and change in cognition., Results: Ng and T-tau distinguished between Aβ+ from Aβ- individuals in each clinical group, whereas NFL and YKL-40 were associated with Aβ+ in nondemented individuals only. APOE ε4 carriership did not influence NFL, Ng, and YKL-40 in Aβ+ individuals. NFL was the best predictor of cognitive decline in Aβ+ individuals across the cognitive spectrum., Discussion: Axonal degeneration, synaptic dysfunction, astroglial activation, and altered tau metabolism are involved already in preclinical AD. NFL may be a useful prognostic marker., (Copyright © 2019 the Alzheimer's Association. All rights reserved.)

Background: Neurogranin in cerebrospinal fluid (CSF) correlates with cognitive decline and is a potential novel biomarker for Alzheimer disease (AD) dementia. We investigated the analytical and diagnostic performance of 3 commonly used neurogranin assays in the same cohort of patients to improve the interpretability of CSF neurogranin test results., Methods: The neurogranin Erenna ® assay from Washington University, St. Louis, MO (WashU); ELISA from ADx Neurosciences; and ELISA from Gothenburg University, Mölndal, Sweden (UGot), were compared using silver staining and Western blot after gel electrophoresis. Clinical performance of the 3 assays was compared in samples from individuals diagnosed with subjective cognitive decline (n = 22), and in patients with AD (n = 22), frontotemporal dementia (n = 22), dementia with Lewy bodies (n = 22), or vascular dementia (n = 20), adjusted for sex and age., Results: The assays detected different epitopes of neurogranin: the WashU assay detected the N-terminal part of neurogranin (S10-D23) and a C-terminal part (G49-G60), the ADx assay detected C-terminal neurogranin truncated at P75, and the UGot assay detected the C-terminal neurogranin with intact ending (D78). Spearman ρ was 0.95 between ADx and WashU, 0.87 between UGot and WashU, and 0.81 between UGot and ADx. ANCOVA (analysis of covariance) showed group differences for ranked neurogranin concentrations in each assay (all P < 0.05), with specific increases in AD., Conclusions: Although the 3 assays target different epitopes on neurogranin and have different calibrators, the high correlations and the similar group differences suggest that the different forms of neurogranin in CSF carry similar diagnostic information, at least in the context of neurodegenerative diseases., (© 2018 American Association for Clinical Chemistry.)

In the 12 years since the publication of the first Consensus Paper of the WFSBP on biomarkers of neurodegenerative dementias, enormous advancement has taken place in the field, and the Task Force takes now the opportunity to extend and update the original paper. New concepts of Alzheimer's disease (AD) and the conceptual interactions between AD and dementia due to AD were developed, resulting in two sets for diagnostic/research criteria. Procedures for pre-analytical sample handling, biobanking, analyses and post-analytical interpretation of the results were intensively studied and optimised. A global quality control project was introduced to evaluate and monitor the inter-centre variability in measurements with the goal of harmonisation of results. Contexts of use and how to approach candidate biomarkers in biological specimens other than cerebrospinal fluid (CSF), e.g. blood, were precisely defined. Important development was achieved in neuroimaging techniques, including studies comparing amyloid-β positron emission tomography results to fluid-based modalities. Similarly, development in research laboratory technologies, such as ultra-sensitive methods, raises our hopes to further improve analytical and diagnostic accuracy of classic and novel candidate biomarkers. Synergistically, advancement in clinical trials of anti-dementia therapies energises and motivates the efforts to find and optimise the most reliable early diagnostic modalities. Finally, the first studies were published addressing the potential of cost-effectiveness of the biomarkers-based diagnosis of neurodegenerative disorders.

Alzheimer's disease (AD) is the most common cause of dementia. Biomarkers are required to identify individuals in the preclinical phase, explain phenotypic diversity, measure progression and estimate prognosis. The development of assays to validate candidate biomarkers is costly and time-consuming. Targeted proteomics is an attractive means of quantifying novel proteins in cerebrospinal and other fluids, and has potential to help overcome this bottleneck in biomarker development. We used a previously validated multiplexed 10-min, targeted proteomic assay to assess 54 candidate cerebrospinal fluid (CSF) biomarkers in two independent cohorts comprising individuals with neurodegenerative dementias and healthy controls. Individuals were classified as 'AD' or 'non-AD' on the basis of their CSF T-tau and amyloid Aβ1-42 profile measured using enzyme-linked immunosorbent assay; biomarkers of interest were compared using univariate and multivariate analyses. In all, 35/31 individuals in Cohort 1 and 46/36 in Cohort 2 fulfilled criteria for AD/non-AD profile CSF, respectively. After adjustment for multiple comparisons, five proteins were elevated significantly in AD CSF compared with non-AD CSF in both cohorts: malate dehydrogenase; total APOE; chitinase-3-like protein 1 (YKL-40); osteopontin and cystatin C. In an independent multivariate orthogonal projection to latent structures discriminant analysis (OPLS-DA), these proteins were also identified as major contributors to the separation between AD and non-AD in both cohorts. Independent of CSF Aβ1-42 and tau, a combination of these biomarkers differentiated AD and non-AD with an area under curve (AUC)=0.88. This targeted proteomic multiple reaction monitoring (MRM)-based assay can simultaneously and rapidly measure multiple candidate CSF biomarkers. Applying this technique to AD we demonstrate differences in proteins involved in glucose metabolism and neuroinflammation that collectively have potential clinical diagnostic utility.

Background: Neuronal damage is the morphological substrate of persisting neurological disability. Neurofilaments (Nf) are specific cytoskeletal proteins of neurons and their quantification has shown encouraging results as a biomarker for axonal injury., Methods: We aimed at comparing a widely used conventional ELISA for Nf light chain (NfL) with an electrochemiluminescence-based method (ECL assay) and a newly developed single-molecule array (Simoa) method in clinically relevant cerebrospinal fluid (CSF) and serum samples., Results: Analytical sensitivity was 0.62 pg/mL for Simoa, 15.6 pg/mL for the ECL assay, and 78.0 pg/mL for the ELISA. Correlations between paired CSF and serum samples were strongest for Simoa (r=0.88, p<0.001) and the ECL assay (r=0.78, p<0.001) and weaker for ELISA measurements (r=0.38, p=0.030). CSF NfL measurements between the platforms were highly correlated (r=1.0, p<0.001). Serum NfL levels were highly related between ECL assay and Simoa (r=0.86, p<0.001), and this was less visible between ELISA-ECL assay (r=0.41, p=0.018) and ELISA-Simoa (r=0.43, p=0.013). Multiple sclerosis (MS) patients had significantly higher serum NfL levels than controls when measured with Simoa (p=0.001) but not with the other platforms., Conclusions: We found Simoa to be more sensitive than ELISA or the ECL assay. Our results support the feasibility of quantifying NfL in serum; the results correlate with the more-established CSF NfL test. The highly sensitive Simoa technology deserves further studies in larger patient cohorts to clarify whether serum NfL could be used in the future to measure disease severity and determine prognosis or response to treatment interventions in neurological diseases.

Background: The cerebrospinal fluid (CSF) amyloid-β (Aβ42) peptide is an important biomarker for Alzheimer's disease (AD). Variability in measured Aβ42 concentrations at different laboratories may be overcome by standardization and establishing traceability to a reference system. Candidate certified reference materials (CRMs) are validated herein for this purpose., Methods: Commutability of 16 candidate CRM formats was assessed across five CSF Aβ42 immunoassays and one mass spectrometry (MS) method in a set of 48 individual clinical CSF samples. Promising candidate CRM formats (neat CSF and CSF spiked with Aβ42) were identified and subjected to validation across eight (Elecsys, EUROIMMUN, IBL, INNO-BIA AlzBio3, INNOTEST, MSD, Simoa, and Saladax) immunoassays and the MS method in 32 individual CSF samples. Commutability was evaluated by Passing-Bablok regression and the candidate CRM termed commutable when found within the prediction interval (PI). The relative distance to the regression line was assessed., Results: The neat CSF candidate CRM format was commutable for almost all method comparisons, except for the Simoa/MSD, Simoa/MS and MS/IBL where it was found just outside the 95% PI. However, the neat CSF was found within 5% relative distance to the regression line for MS/IBL, between 5% and 10% for Simoa/MS and between 10% and 15% for Simoa/MSD comparisons., Conclusions: The neat CSF candidate CRM format was commutable for 33 of 36 method comparisons, only one comparison more than expected given the 95% PI acceptance limit. We conclude that the neat CSF candidate CRM can be used for value assignment of the kit calibrators for the different Aβ42 methods.

Background: Alzheimer's disease biomarkers are important for early diagnosis in routine clinical practice and research. Three core CSF biomarkers for the diagnosis of Alzheimer's disease (Aβ42, T-tau, and P-tau) have been assessed in numerous studies, and several other Alzheimer's disease markers are emerging in the literature. However, there have been no comprehensive meta-analyses of their diagnostic performance. We systematically reviewed the literature for 15 biomarkers in both CSF and blood to assess which of these were most altered in Alzheimer's disease., Methods: In this systematic review and meta-analysis, we screened PubMed and Web of Science for articles published between July 1, 1984, and June 30, 2014, about CSF and blood biomarkers reflecting neurodegeneration (T-tau, NFL, NSE, VLP-1, and HFABP), APP metabolism (Aβ42, Aβ40, Aβ38, sAPPα, and sAPPβ), tangle pathology (P-tau), blood-brain-barrier function (albumin ratio), and glial activation (YKL-40, MCP-1, and GFAP). Data were taken from cross-sectional cohort studies as well as from baseline measurements in longitudinal studies with clinical follow-up. Articles were excluded if they did not contain a cohort with Alzheimer's disease and a control cohort, or a cohort with mild cognitive impairment due to Alzheimer's disease and a stable mild cognitive impairment cohort. Data were extracted by ten authors and checked by two for accuracy. For quality assessment, modified QUADAS criteria were used. Biomarker performance was rated by random-effects meta-analysis based on the ratio between biomarker concentration in patients with Alzheimer's disease and controls (fold change) or the ratio between biomarker concentration in those with mild cognitive impariment due to Alzheimer's disease and those with stable mild cognitive impairment who had a follow-up time of at least 2 years and no further cognitive decline., Findings: Of 4521 records identified from PubMed and 624 from Web of Science, 231 articles comprising 15 699 patients with Alzheimer's disease and 13 018 controls were included in this analysis. The core biomarkers differentiated Alzheimer's disease from controls with good performance: CSF T-tau (average ratio 2·54, 95% CI 2·44-2·64, p<0·0001), P-tau (1·88, 1·79-1·97, p<0·0001), and Aβ42 (0·56, 0·55-0·58, p<0·0001). Differentiation between cohorts with mild cognitive impairment due to Alzheimer's disease and those with stable mild cognitive impairment was also strong (average ratio 0·67 for CSF Aβ42, 1·72 for P-tau, and 1·76 for T-tau). Furthermore, CSF NFL (2·35, 1·90-2·91, p<0·0001) and plasma T-tau (1·95, 1·12-3·38, p=0·02) had large effect sizes when differentiating between controls and patients with Alzheimer's disease, whereas those of CSF NSE, VLP-1, HFABP, and YKL-40 were moderate (average ratios 1·28-1·47). Other assessed biomarkers had only marginal effect sizes or did not differentiate between control and patient samples., Interpretation: The core CSF biomarkers of neurodegeneration (T-tau, P-tau, and Aβ42), CSF NFL, and plasma T-tau were strongly associated with Alzheimer's disease and the core biomarkers were strongly associated with mild cognitive impairment due to Alzheimer's disease. Emerging CSF biomarkers NSE, VLP-1, HFABP, and YKL-40 were moderately associated with Alzheimer's disease, whereas plasma Aβ42 and Aβ40 were not. Due to their consistency, T-tau, P-tau, Aβ42, and NFL in CSF should be used in clinical practice and clinical research., Funding: Swedish Research Council, Swedish State Support for Clinical Research, Alzheimer's Association, Knut and Alice Wallenberg Foundation, Torsten Söderberg Foundation, Alzheimer Foundation (Sweden), European Research Council, and Biomedical Research Forum., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Introduction: Available assays for quantitation of the Alzheimer's disease (AD) biomarker amyloid-beta 1-42 (Aβ [1-42]) in cerebrospinal fluid demonstrate significant variability and lack of standardization to reference measurement procedures (RMPs). We report analytical performance data for the novel Elecsys β-amyloid (1-42) assay (Roche Diagnostics)., Methods: Lot-to-lot comparability was tested using method comparison. Performance parameters were measured according to Clinical & Laboratory Standards Institute (CLSI) guidelines. The assay was standardized to a Joint Committee for Traceability in Laboratory Medicine (JCTLM) approved RMP., Results: Limit of quantitation was <11.28 pg/mL, and the assay was linear throughout the measuring range (200-1700 pg/mL). Excellent lot-to-lot comparability was observed (correlation coefficients [Pearson's r] >0.995; bias in medical decision area <2%). Repeatability coefficients of variation (CVs) were 1.0%-1.6%, intermediate CVs were 1.9%-4.0%, and intermodule CVs were 1.1%-3.9%. Estimated total reproducibility was 2.0%-5.1%. Correlation with the RMP was good (Pearson's r, 0.93)., Discussion: The Elecsys β-amyloid (1-42) assay has high analytical performance that may improve biomarker-based AD diagnosis., (Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.)

Pathobiological factors underlying phenotypic diversity in Alzheimer's disease (AD) are incompletely understood. We used an extended cerebrospinal fluid (CSF) panel to explore differences between "typical" with "atypical" AD and between amnestic, posterior cortical atrophy, logopenic aphasia and frontal variants. We included 97 subjects fulfilling International Working Group-2 research criteria for AD of whom 61 had "typical" AD and 36 "atypical" syndromes, and 30 controls. CSF biomarkers included total tau (T-tau), phosphorylated tau (P-tau), amyloid β1-42, amyloid βX-38/40/42, YKL-40, neurofilament light (NFL), and amyloid precursor proteins α and β. The typical and atypical groups were matched for age, sex, severity and rate of cognitive decline and had similar biomarker profiles, with the exception of NFL which was higher in the atypical group (p = 0.03). Sub-classifying the atypical group into its constituent clinical syndromes, posterior cortical atrophy was associated with the lowest T-tau [604.4 (436.8-675.8) pg/mL], P-tau (79.8 ± 21.8 pg/L), T-tau/Aβ1-42 ratio [2.3 (1.4-2.6)], AβX-40/X-42 ratio (22.1 ± 5.8) and rate of cognitive decline [1.9 (0.75-4.25) MMSE points/year]. Conversely, the frontal variant group had the highest levels of T-tau [1185.4 (591.7-1329.3) pg/mL], P-tau (116.4 ± 45.4 pg/L), T-tau/Aβ1-42 ratio [5.2 (3.3-6.9)] and AβX-40/X-42 ratio (27.9 ± 7.5), and rate of cognitive decline. Whilst on a group level IWG-2 "typical" and "atypical" AD share similar CSF profiles, which are very different from controls, atypical AD is a heterogeneous entity with evidence for subtle differences in amyloid processing and neurodegeneration between different clinical syndromes. These findings also have practical implications for the interpretation of clinical CSF biomarker results.

Introduction: Synaptic dysfunction is an early event in Alzheimer's disease (AD) pathogenesis and directly related to cognitive impairment. Consequently, synaptic biomarkers may be valuable tools for both early diagnosis and disease stage. Neurogranin (Ng) is a postsynaptic protein involved in memory consolidation., Methods: We developed three monoclonal anti-Ng antibodies. Mass spectrometry and a novel enzyme-linked immunosorbent assay were used to analyze cerebrospinal fluid (CSF) Ng in three independent clinical cohorts including patients with AD dementia (n = 100 in total), mild cognitive impairment patients (MCI), (n = 40) and controls (n = 80 in total)., Results: We show in three independent clinical cohorts a marked increase in CSF Ng levels in AD dementia (P < .001 in all studies). In addition, high CSF Ng levels at the MCI stage predicted progression to dementia due to AD with a hazard ratio of 12.8 (95% confidence interval 1.6-103.0, P = .02). In amyloid-positive MCI patients, high CSF Ng correlated with a more rapid change in cognition during clinical follow-up (P = .03)., Discussion: These results suggest that CSF Ng is a novel AD biomarker that may be used to monitor synaptic degeneration, and correlates with the rate of cognitive decline in prodromal AD., (Copyright © 2015 The Alzheimer's Association. Published by Elsevier Inc. All rights reserved.)

Objective: To investigate glial and neuronal biomarkers in cerebrospinal fluid (CSF) samples from patients with relapsing-remitting multiple sclerosis (RRMS) and clinically isolated syndrome (CIS) suggestive of multiple sclerosis (MS), and to evaluate their ability to predict conversion from CIS to clinically definite MS (CDMS) and also disability progression in MS., Methods: CSF levels of neurofilament light protein (NFL), t-tau, p-tau, glial fibrillary acidic protein (GFAP), S-100B, human chitinase 3-like 1 protein (YKL-40), monocyte chemoattractant protein-1 (MCP-1), α-sAPP and β-sAPP; and Aβ38, Aβ40 and Aβ42, were analyzed in 109 CIS patients and 192 RRMS patients. The mean follow-up time of these 301 patients was 11.7 ± 6.4 years., Results: High levels of NFL were associated with early conversion from CIS to CDMS (hazard ratio (HR) with 95% confidence interval (CI): 2.69 (1.75 - 4.15); p < 0.0001). High levels of YKL-40 and GFAP were associated with earlier progression in the Expanded Disability Status Scale (EDSS), score 3: YKL-40 (HR (95% CI): 2.78 (1.48 - 5.23); p = 0.001) and GFAP (HR (95% CI): 1.83 (1.01 - 3.35); p = 0.04). High levels of YKL-40 were associated with earlier progression to EDSS 6 (HR (95% CI): 4.57 (1.01 - 20.83); p = 0.05)., Conclusions: CSF levels of NFL in CIS patients are an independent prognostic marker for conversion to CDMS. Whereas, CSF levels of YKL-40 and GFAP are independent prognostic markers for disability progression in MS., (© The Author(s), 2015.)

Introduction: There is an unmet need for biomarkers for Parkinson's disease (PD) and atypical parkinsonian disorders (APD). α-Synuclein, linked to the pathogenesis of PD, is a promising biomarker candidate in need of further investigation. The ubiquitin carboxy-terminal hydrolase L1 (UCH-L1), a pivotal component of the ubiquitin proteasome system which seems to be disturbed in PD, may also be involved in the pathogenesis of this disorder., Methods: We investigated cerebrospinal fluid (CSF) α-synuclein and UCH-L1 levels from 22 healthy controls, 52 patients with PD, 34 with multiple system atrophy (MSA), 32 with progressive supranuclear palsy, and 12 with corticobasal degeneration., Results: α-Synuclein levels were significantly decreased in PD and in MSA compared with controls, and in synucleinopathies compared with tauopathies. UCH-L1 levels were significantly decreased in PD, MSA as well as PSP compared with controls, and in PD compared with APD (p < 0.001). Both markers discriminated PD well from controls (p < 0.0001; area under the curve [AUC] = 0.82 and 0.89, respectively). Additionally, CSF α-synuclein separated patients with synucleinopathies from those with tauopathies (p = 0.015; AUC = 0.63), whereas CSF UCH-L1 discriminated between PD and APD (p = 0.0003; AUC = 0.69). Interestingly, α-synuclein and UCH-L1 levels were strongly correlated in PD and synucleinopathies, and weakly in tauopathies. No correlation was found in controls., Conclusions: CSF levels of α-synuclein and UCH-L1 show distinct patterns in parkinsonian syndromes. Their combined determination may be useful in the differential diagnosis of parkinsonian disorders and provide key to understanding their pathoetiology and clinical course. Further large studies are needed to validate our findings., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Aim: The aim of this study was to investigate the levels of various cerebrospinal fluid (CSF) biomarkers related to neuronal damage, inflammation and amyloid β (Aβ) metabolism in patients resuscitated after an out-of-hospital cardiac arrest (CA)., Methods: CSF levels of neurofilament light protein (NFL), total tau (T-tau), hyperphosphorylated tau (P-tau), YKL-40, Aβ38, Aβ40, Aβ42, soluble amyloid precursor protein α and β (sAPPα and sAPPβ) were measured in 21 patients approximately two weeks after CA and in 21 age-matched neurologically healthy controls. The biomarker levels were also compared between patients with good and poor long-term clinical outcome according to Glasgow Outcome Scale (GOS), activities of daily living (ADL) and mini-mental state examination (MMSE), measuring neurologic function, daily functioning and cognitive function, respectively., Results: Patients with CA had a very marked increase in the CSF levels of NFL, T-tau and YKL-40 as compared with controls. The levels were increased at about 1200, 700 and 100%, respectively. NFL and T-tau were significantly higher in patients with poor outcome according to all three outcome measures. Patients with poor outcome according to GOS and ADL had higher levels of YKL-40. Levels of Aβ38, Aβ40, Aβ42, sAPPα and sAPPβ were lower in patients with a low MMSE score. P-tau was not significantly altered., Conclusions: Biomarkers reflecting neuronal damage and inflammation, but not so much Aβ metabolism, were significantly altered in patients after a CA, and the changes were more pronounced in the groups with poor outcome. This calls for future larger studies to determine the prognostic potential of these biomarkers., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Background: The cerebrospinal fluid (CSF) biomarkers amyloid beta 1-42, total tau, and phosphorylated tau are used increasingly for Alzheimer's disease (AD) research and patient management. However, there are large variations in biomarker measurements among and within laboratories., Methods: Data from the first nine rounds of the Alzheimer's Association quality control program was used to define the extent and sources of analytical variability. In each round, three CSF samples prepared at the Clinical Neurochemistry Laboratory (Mölndal, Sweden) were analyzed by single-analyte enzyme-linked immunosorbent assay (ELISA), a multiplexing xMAP assay, or an immunoassay with electrochemoluminescence detection., Results: A total of 84 laboratories participated. Coefficients of variation (CVs) between laboratories were around 20% to 30%; within-run CVs, less than 5% to 10%; and longitudinal within-laboratory CVs, 5% to 19%. Interestingly, longitudinal within-laboratory CV differed between biomarkers at individual laboratories, suggesting that a component of it was assay dependent. Variability between kit lots and between laboratories both had a major influence on amyloid beta 1-42 measurements, but for total tau and phosphorylated tau, between-kit lot effects were much less than between-laboratory effects. Despite the measurement variability, the between-laboratory consistency in classification of samples (using prehoc-derived cutoffs for AD) was high (>90% in 15 of 18 samples for ELISA and in 12 of 18 samples for xMAP)., Conclusions: The overall variability remains too high to allow assignment of universal biomarker cutoff values for a specific intended use. Each laboratory must ensure longitudinal stability in its measurements and use internally qualified cutoff levels. Further standardization of laboratory procedures and improvement of kit performance will likely increase the usefulness of CSF AD biomarkers for researchers and clinicians., (Copyright © 2013 The Alzheimer's Association. Published by Elsevier Inc. All rights reserved.)

Background: Low levels of serum urate are associated with a higher risk of Parkinson's disease (PD). Higher serum and cerebrospinal fluid (CSF) urate levels are associated with slower rates of clinical decline in PD and in multiple system atrophy (MSA)., Aims: To compare CSF and blood urate levels in healthy controls, patients with synucleinopathies and with tauopathies., Methods: We investigated urate levels in serum and CSF from 18 healthy controls, 19 patients with synucleinopathies (six patients with PD and 13 with MSA), and 24 patients with tauopathies (18 with progressive supranuclear palsy and six with corticobasal degeneration). None of the patients were treated with dopaminergic medications., Results: No significant differences were seen when comparing serum and CSF urate levels from controls across the parkinsonian diagnostic groups. However, in men, serum urate levels were significantly lower in the synucleinopathy group compared with the tauopathy group (P = 0.046), although with a broad overlap., Conclusion: Our study suggests that urate levels might provide new insights into the potential pathophysiological mechanisms underlying Parkinsonism and thereby contribute to the future management of these disorders., (© 2012 John Wiley & Sons A/S.)

Objective: To assess the ability of 5 cerebrospinal fluid(CSF) biomarkers to differentiate between common dementia and parkinsonian disorders., Design: A cross-sectional, clinic-based study., Participants: Cerebrospinal fluid samples (N=453) were obtained from healthy individuals serving as controls and from patients with Parkinson disease (PD), PD with dementia(PDD), dementia with Lewy bodies (DLB), Alzheimer disease (AD), progressive supranuclear palsy(PSP), multiple system atrophy (MSA), or corticobasal degeneration (CBD)., Setting: Neurology and memory disorder clinics., Main Outcome Measures: Cerebrospinal fluid biomarker levels in relation to clinical diagnosis., Results: Cerebrospinal fluid levels of -synuclein were decreased in patients with PD, PDD, DLB, and MSA but increased in patients with AD. Cerebrospinal fluid levels of α-amyloid 1-42 were decreased in DLB and even further decreased in AD. Cerebrospinal fluid levels of total tau and hyperphosphorylated tau were increased in AD. Multivariate analysis revealed that these biomarkers could differentiate AD from DLB and PDD with an area under the curve of 0.90, with -synuclein and total tau contributing most to the model. Cerebrospinal fluid levels of neurofilament light chain were substantially increased in atypical parkinsonian disorders (ie, PSP, MSA,and CBD), and multivariate analysis revealed that the level of neurofilament light chain alone could differentiate PD from atypical parkinsonian disorders, with an area under the curve of 0.93., Conclusions: Ascertainment of the -synuclein level in CSF somewhat improves the differential diagnosis of AD vs DLB and PDD when combined with established AD biomarkers.The level of neurofilament light chain alone may differentiate PD from atypical parkinsonian disorders.

Background: The cerebrospinal fluid (CSF) biomarkers amyloid β (Aβ)-42, total-tau (T-tau), and phosphorylated-tau (P-tau) demonstrate good diagnostic accuracy for Alzheimer's disease (AD). However, there are large variations in biomarker measurements between studies, and between and within laboratories. The Alzheimer's Association has initiated a global quality control program to estimate and monitor variability of measurements, quantify batch-to-batch assay variations, and identify sources of variability. In this article, we present the results from the first two rounds of the program., Methods: The program is open for laboratories using commercially available kits for Aβ, T-tau, or P-tau. CSF samples (aliquots of pooled CSF) are sent for analysis several times a year from the Clinical Neurochemistry Laboratory at the Mölndal campus of the University of Gothenburg, Sweden. Each round consists of three quality control samples., Results: Forty laboratories participated. Twenty-six used INNOTEST enzyme-linked immunosorbent assay kits, 14 used Luminex xMAP with the INNO-BIA AlzBio3 kit (both measure Aβ-(1-42), P-tau(181P), and T-tau), and 5 used Meso Scale Discovery with the Aβ triplex (AβN-42, AβN-40, and AβN-38) or T-tau kits. The total coefficients of variation between the laboratories were 13% to 36%. Five laboratories analyzed the samples six times on different occasions. Within-laboratory precisions differed considerably between biomarkers within individual laboratories., Conclusions: Measurements of CSF AD biomarkers show large between-laboratory variability, likely caused by factors related to analytical procedures and the analytical kits. Standardization of laboratory procedures and efforts by kit vendors to increase kit performance might lower variability, and will likely increase the usefulness of CSF AD biomarkers., (Copyright © 2011 The Alzheimer's Association. Published by Elsevier Inc. All rights reserved.)

Parkinson's disease (PD) and atypical parkinsonian disorders (APD), including multiple system atrophy (MSA), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD), are a group of neurodegenerative diseases sharing many similar signs and symptoms but distinguished by their particular clinical features, treatment response, prognosis and mortality. The differential diagnosis may be challenging, especially in early disease stages. Considering the importance of an accurate diagnosis both for clinical management and for research, new diagnostic tools are needed. In this study, we investigated 56 PD, 42 MSA, 39 PSP, 9 CBD patients, and 24 healthy controls. After screening the cerebrospinal fluid (CSF) proteome using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS), we identified 4 proteins (ubiquitin [mass-to-charge ratio (m/z) 8590], beta2-microglobulin [m/z 11730], and 2 secretogranin 1 [chromogranin B] fragments [m/z 7260 and m/z 6250]) that differentiated healthy controls and PD patients from patients with APD. However, they could not differentiate PD patients from controls. As none of these changes were APD subgroup-specific, they most likely reflect the intensity and/or extent of the neurodegenerative process in general., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Background: Mild cognitive impairment (MCI) is a heterogeneous condition, and the prognosis differs within the group. Recent findings suggest that hippocampal volumetry and CSF biomarkers can be used to predict which MCI patients have an underlying neurodegenerative disorder., Objective: To examine the combined predictive value of hippocampal volume and CSF levels of total tau (T-tau) and beta-amyloid(42) (Abeta(42)) in stable and converting MCI patients. The participants (n = 68) included patients with MCI at baseline and who converted to dementia by the time of the 2-year follow-up (n = 21), stable MCI patients (n = 21) and healthy controls (n = 26)., Methods: The Göteborg MCI study is a clinically based longitudinal study with biannual clinical assessments. Hippocampal volumetry was performed manually, based on data from the 0.5-tesla MRI investigations at baseline. Baseline CSF levels of T-tau and Abeta(42) were measured using commercially available, enzyme-linked immunosorbent assays., Results: The converting MCI group had significantly smaller left hippocampi, lower CSF Abeta(42) and higher T-tau compared to both the stable MCI group and the healthy controls. Multivariate analysis revealed that a combination of the variables outperformed the prognostic ability of the separate variables., Conclusions: Hippocampal volumes supplement the prognostic accuracy of CSF Abeta(42) and T-tau in MCI., (Copyright (c) 2010 S. Karger AG, Basel.)

Neurodegenerative diseases are characterized by premature neuronal loss in specific brain regions. During the past decades our knowledge on molecular mechanisms underlying neurodegeneration has increased immensely and resulted in promising drug candidates that might slow down or even stop the neuronal loss. These advances have put a strong focus on the development of diagnostic tools for early or pre-clinical detection of the disorders. In this review we discuss our experience in the field of neuroproteomics/peptidomics, with special focus on biomarker discovery studies that have been performed on CSF samples from well-defined patient and control populations.

Background and purpose Cerebrospinal fluid ( CSF) tau and neurofilament light chain ( NF-L) proteins have proved to be reliable biomarkers for neuronal damage; however, there is a strong need for blood-based tests. Methods The present study included 132 autopsy cases with rapidly progressive neurological syndromes, including Alzheimer disease ( AD) (21), sporadic (65) and genetic (21) Creutzfeldt-Jakob disease ( CJD), 25 cases with vascular, neoplastic and inflammatory alterations, and additionally 18 healthy control individuals. CSF tau and NF-L concentrations were measured by enzyme-linked immunosorbent assay. Plasma tau and NF-L concentrations were measured using ultra-sensitive single molecule array technology. Results Plasma and CSF tau ( R = 0.59, P < 0.001) and NF-L ( R = 0.69, P < 0.001) levels correlated significantly (Spearman test). Plasma tau and NF-L levels were significantly higher in all disease groups compared to healthy controls ( P < 0.001). Receiver operating characteristic curves were used and area under the curve values for comparisons with controls were 0.82 ( AD), 0.94 (sporadic CJD), 0.92 (genetic CJD) and 0.83 (other neurological disorders) for plasma tau and 0.99, 0.99, 1.00 and 0.96 for plasma NF-L, respectively. Molecular subtyping of sporadic CJD showed a strong effect (linear logistic regression) on plasma tau ( P < 0.001) but not NF-L levels ( P = 0.19). Conclusion Plasma tau and NF-L concentrations are strongly increased in CJD and show similar diagnostic performance to the corresponding CSF measure. Molecular subtypes of sporadic CJD show different levels of plasma tau. Although not disease-specific, these findings support the use of plasma tau and NF-L as tools to identify, or to rule out, neurodegeneration. [ABSTRACT FROM AUTHOR]

Neurodegenerative disorders are characterized by neuronal impairment that eventually leads to neuronal death. In spite of the brain’s known capacity for regeneration, lost neurons are difficult to replace. Therefore, drugs aimed at inhibiting neurodegenerative processes are likely to be most effective if the treatment is initiated as early as possible. However, clinical manifestations in early disease stages are often numerous, subtle and difficult to diagnose. This is where biomarkers that specifically reflect onset of pathology, directly or indirectly, may have a profound impact on diagnosis making in the future. A triplet of biomarkers for Alzheimer’s disease (AD), total and hyperphosphorylated tau and the 42 amino acid isoform of β-amyloid, has already been established for early detection of AD before the onset of dementia. However, more biomarkers are needed both for AD and for other neurodegenerative disorders, such as Parkinson’s disease, frontotemporal dementia and amyotrophic lateral sclerosis. This review provides an update on recent advances in clinical neuroproteomics, a biomarker discovery field that has expanded immensely during the last decade, and gives an overview of the most commonly used techniques and the major clinically relevant findings these techniques have lead to. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented which clarifies the benefits of using biomarker-assisted diagnosis-making in patients with genetic and cerebrospinal fluid (CSF) biomarker data to determine the pathology for Alzheimers's disease.