Search

Background: Plasma phospho-tau 217 (pTau217) assays can accurately detect Alzheimer's disease (AD) pathology, but clinical application is limited by the need for specialised equipment. This study tests the performance of a plasma pTau217 assay performed on the Lumipulse-G® platform, that is in widespread clinical use, for selecting patients for therapy based on β-amyloid (Aβ) status and tau staging., Methods: Participants included 388 individuals with 18 F-NAV4694 Aβ-PET and 18 F-MK6240 tau-PET. Association of pTau217 with PET was examined using Spearman's correlation. Discriminative performance for Aβ and tau PET status as well as tau staging was assessed using Receiver Operating Characteristic analysis., Findings: Plasma pTau217 had a high correlation with both Aβ Centiloid (r = 0.76) and tau SUVR meta-temporal (r = 0.78). Area under curve (AUC) was 0.93 for Aβ- vs Aβ+ and 0.94 for tau- vs tau+. Applying one threshold (Youden's index), pTau217 was 87% accurate in classification of participants to Aβ- vs Aβ+. Applying two thresholds to classify participants into Low, Indeterminate, and High zones, 17.8% had Indeterminate results and among Low/High zone participants, 92% were correctly classified as Aβ- or Aβ+. The assay accurately discriminated moderate/high neocortical tau from no tau or tau limited to mesial-temporal lobe (AUC 0.97) and high neocortical tau from all others (AUC 0.94)., Interpretation: Plasma pTau217, measured by the widely-available, fully-automated Lumipulse®, was a strong predictor of both Aβ and tau PET status and demonstrated strong predictive power in identifying individuals likely to benefit the most from anti-Aβ treatments., Funding: NHMRC grants 1132604, 1140853, 1152623 and AbbVie., Competing Interests: Declaration of interests CCR has received research grants from NHMRC, Enigma Australia, Biogen, Eisai and Abbvie. He is on the scientific advisory board for Cerveau Technologies and has consulted for Prothena, Eisai, Roche, and Biogen Australia. VLV has received a grant from NIA and is and has been a consultant or paid speaker at sponsored conference sessions for Eli Lilly, Life Molecular Imaging, ACE Barcelona, and BRI Japan. ES and AWB are employees of Abbvie. SML is a scientific advisor for Cytox Ltd. SA has received grants from NHMRC, MRFF, and NIH and consulting fees from Eisai Australia. SRS has received grants from NHMRC, Alzheimer's Association (USA), Alzheimer's Drug Discovery Foundation, and Bright Focus Foundation and had a paid role in MRFF Grant Assessment Committee. The other authors did not report any conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Introduction: Frontotemporal lobar degeneration (FTLD) encompasses behavioral variant frontotemporal dementia (bvFTD), progressive supranuclear palsy, corticobasal syndrome/degeneration, and primary progressive aphasias (PPAs). We cross-validated fluid biomarkers and neuroimaging., Methods: Seven fluid biomarkers from cerebrospinal fluid and serum were related to atrophy in 428 participants including these FTLD subtypes, logopenic variant PPA (lvPPA), Alzheimer's disease (AD), and healthy subjects. Atrophy was assessed by structural magnetic resonance imaging and atlas-based volumetry., Results: FTLD subtypes, lvPPA, and AD showed specific profiles for neurofilament light chain, phosphorylated heavy chain, tau, phospho-tau, amyloid beta 1-42 from serum/cerebrospinal fluid, and brain atrophy. Neurofilaments related to regional atrophy in bvFTD, whereas progranulin was associated with atrophy in semantic variant PPA. Ubiquitin showed no effects., Discussion: Results specify biomarker and atrophy patterns in FTLD and AD supporting differential diagnosis. They identify neurofilaments and progranulin in interaction with structural imaging as promising candidates for monitoring disease progression and therapy., Highlights: Study cross-validated neuroimaging and fluid biomarkers in dementia. Five kinds of frontotemporal lobar degeneration and two variants of Alzheimer's disease. Study identifies disease-specific fluid biomarker and atrophy profiles. Fluid biomarkers and atrophy interact in a disease-specific way. Neurofilaments and progranulin are proposed as biomarkers for diagnosis and therapy., (© 2024 The Author(s). Alzheimer's & Dementia published by Wiley Periodicals LLC on behalf of Alzheimer's Association.)

To identify long-term effects of traumatic brain injury (TBI) on levels of plasma neuron-derived exosome (NDE) protein biomarkers of cognitive impairment (CI), plasmas were obtained from four groups of older veterans, who were matched for age and sex: no TBI or CI ( n  = 42), no TBI with CI ( n  = 19), TBI without CI ( n  = 21), and TBI with CI ( n  = 26). The TBI was sustained 12 to 74 years before the study in 75%. The NDEs were enriched by sequential precipitation and anti-L1CAM antibody immunoabsorption, and extracted protein biomarkers were quantified by enzyme-linked immunosorbent assays. Chronic NDE biomarkers known to increase for three to 12 months after TBI, including cellular prion protein (PrPc), synaptogyrin-3, P-T181-tau, P-S396-tau, Aβ42, and interleukin (IL)-6, were elevated significantly in subjects who had TBI and CI compared with controls with TBI but no CI. Chronic NDE biomarker levels in subjects without TBI showed significantly higher levels of PrPc, synaptogyrin-3, P-T181-tau, and Aβ42, but not P-S396-tau and IL-6, in those with CI compared with controls without CI. The acute NDE biomarkers claudin-5, annexin VII, and aquaporin-4 were not increased in either group with CI. The NDE biomarkers P-S396-tau and IL-6, which are increased distinctively with CI after TBI, may prove useful in evaluating CI in older patients. Aβ42 and P-tau species, as well as their respective putative receptors, PrPc and synaptogyrin-3, remain elevated for decades after TBI and may mediate TBI-associated CI and be useful targets for development of drugs.

Background: Neuropathological studies indicate concomitant Alzheimer's disease (AD) pathology in patients with dementia with Lewy bodies (DLB)., Objectives: To measure cerebrospinal fluid (CSF) levels of β-amyloid peptide with 42 amino acids (Aβ42), total tau protein (τT), and tau phosphorylated at threonine 181 (τP-181) in 38 patients fulfilling the diagnostic criteria of probable DLB according to the most recent (4th consensus) report., Methods: Double-sandwich commercial ELISAs (Innotest; Fujirebio, Gent, Belgium) were used for measurements., Results: According to the current cutoff values of our laboratory, 4 biomarker profiles were noted: abnormal levels of Aβ42 only (44.7%), full AD profile (39.5%), abnormal levels of τT only (5.3%), and normal levels of all 3 biomarkers (10.5%). AD profile was associated with female sex, older age, lower education, and lower MMSE scores., Conclusions: Reduction in Αβ42 in DLB may be more common (>80% of patients) than previously thought, and ∼40% may have the typical CSF AD biomarker profile. AD biochemistry in DLB may be an evolving process showing increasing frequency with disease progression., (© 2019 S. Karger AG, Basel.)

The cerebrospinal fluid (CSF) biomarkers β-amyloid1-42 (Aβ1-42), total tau protein (T-tau) and hyperphosphorylated tau (P-tau181P) are well-validated and are increasingly used in clinical practice as an affirmative diagnostic tool for Alzheimer's disease (AD). These biomarkers have also been implemented in the revised diagnostic criteria of AD. The combination of the CSF biomarkers Aβ1-42, T-tau and P-tau181P results in high levels of sensitivity, specificity and diagnostic accuracy for discriminating AD from controls (including psychiatric disorders like depression). These biomarkers can be applied for diagnosing AD in the prodromal phase of the disease (mild cognitive impairment). In case of doubt between vascular dementia (VaD) or mixed AD-VaD pathology in dementia patients, the determination of CSF Aβ1-42, T-tau and P-tau181P levels is of help to confirm or exclude the AD component in the pathophysiology of the dementia syndrome. However, their discriminatory power for the differential diagnosis of dementia is suboptimal. Other CSF biomarkers like Aβ1-40, and those that are reflective of the pathology of non-AD dementias, could improve the accuracy of differential dementia diagnosis. The added differential diagnostic value of the CSF biomarkers Aβ1-42, T-tau and P-tau181P could lie within those cases in which the routine clinical diagnostic work-up is not able to discriminate between AD or non-AD dementias. In summary, the CSF biomarkers Aβ1-42, T-tau and P-tau181P can be used in clinical practice to discriminate AD from healthy aging (including psychiatric disorders like depression), to diagnose AD in its prodromal phase or in atypical forms with prominent non-memory impairment, to identify AD in patients with mixed pathologies and in case of an ambiguous (AD versus non-AD) dementia diagnosis., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)

Background: Alzheimer's disease (AD) may present with pure (typical or atypical) and mixed phenotypes, sometimes causing difficulties in (differential) diagnosis. In order to achieve a diagnostic accuracy as high as possible, the diagnosis of AD during life depends on various biomarkers, including the cerebrospinal fluid (CSF) biomarkers. Methods: Classical CSF AD biomarkers were determined in a total of 61 patients, classified as both beta amyloid- and tau-positive A+T+ (or A+T1+ according to the recently revised Alzheimer Association criteria for diagnosis and staging of AD). Twenty one of these patients fulfilled the criteria for mixed AD (mixed with Lewy bodies, cerebrovascular disease, or normal pressure hydrocephalus), whilst 40 had pure AD. Results: Patients did not differ with respect to gender, education, disease duration, and cognitive status. After controlling for confounding factors, no difference was observed between mixed and pure AD groups in Aβ42 or Aβ42/Aβ40 levels. Although by definition, patients of both groups had abnormal (increased) levels of phospho-tau181, the mixed AD group presented with lower (less abnormal) levels of phospho-tau181 and total tau as compared to the pure group. Conclusions: In patients with AD of comparable cognitive status, mixed AD cases may present with lower levels of tau proteins and, if close to the cut-off values, diagnostic uncertainty may be increased. [ABSTRACT FROM AUTHOR]

Background: Alzheimer’s disease (AD) may present with pure (typical or atypical) and mixed phenotypes, sometimes causing difficulties in (differential) diagnosis. In order to achieve a diagnostic accuracy as high as possible, the diagnosis of AD during life depends on various biomarkers, including the cerebrospinal fluid (CSF) biomarkers. Methods: Classical CSF AD biomarkers were determined in a total of 61 patients, classified as both beta amyloid- and tau-positive A+T+ (or A+T1+ according to the recently revised Alzheimer Association criteria for diagnosis and staging of AD). Twenty one of these patients fulfilled the criteria for mixed AD (mixed with Lewy bodies, cerebrovascular disease, or normal pressure hydrocephalus), whilst 40 had pure AD. Results: Patients did not differ with respect to gender, education, disease duration, and cognitive status. After controlling for confounding factors, no difference was observed between mixed and pure AD groups in Aβ42 or Aβ42/Aβ40 levels. Although by definition, patients of both groups had abnormal (increased) levels of phospho-tau181, the mixed AD group presented with lower (less abnormal) levels of phospho-tau181 and total tau as compared to the pure group. Conclusions: In patients with AD of comparable cognitive status, mixed AD cases may present with lower levels of tau proteins and, if close to the cut-off values, diagnostic uncertainty may be increased.

Background: Alzheimer´s disease is considered a neurodegenerative disease and is diagnosed by exclusion, while the detection of specific cerebrospinal fluid (CSF) biomarkers, namely amyloid-beta (Aβ) peptides Aβ1–42 (Aß42), phospho-tau (181P; P-tau), and total-tau (T-tau), has been shown to improve diagnostic accuracy. Recently, a new generation of sample tubes (Sarstedt false-bottom tubes) for the Elecsys CSF immunoassay for the determination of Alzheimer´s disease biomarkers in CSF was introduced, promising better measurability. However, the pre-analytic influencing factors have not yet been sufficiently investigated. Methods: In 29 patients without Alzheimer's disease diagnosis, CSF concentrations of Aß42, P-tau and T-tau were examined in native CSF and after different influencing interventions using the Elecsys immunoassay test method. The following influencing factors were analyzed: contamination with blood (10,000 and 20,000 erythrocytes/µl CSF), 14-day storage at 4 °C, blood contamination of CSF and 14-day storage at 4 °C, 14-day freezing at -80 °C in Sarstedt tubes or glass vials, 3-month intermediate storage at -80 °C in glass vials. Results: Both storage at -80 °C for 14 days in Sarstedt false-bottom tubes and in glass vials and storage at -80 °C for 3 months in glass vials resulted in significant decreases in Aß42 (13% after 14 days in Sarstedt and 22% in glass vials, 42% after 3 months in glass vials), P-tau (9% after 14 days in Sarstedt and 13% in glass vials, 12% after 3 months in glass vials) and T-tau (12% after 14 days in Sarstedt and 19% in glass vials, 20% after 3 months in glass vials) concentrations in CSF. No significant differences were found for the other pre-analytical influencing factors. Conclusions: Measurements of the concentrations of Aß42, P-tau, and T-tau in CSF with use of the Elecsys immunoassay are robust to the pre-analytical influencing factors of blood contamination and duration of storage. Freezing at -80 °C results in significant reduction of biomarker concentrations regardless of the storage tube and must be considered in retrospective analysis. [ABSTRACT FROM AUTHOR]

Abstract Background The recent promise of disease-modifying therapies for Alzheimer’s disease (AD) has reinforced the need for accurate biomarkers for early disease detection, diagnosis and treatment monitoring. Advances in the development of novel blood-based biomarkers for AD have revealed that plasma levels of tau phosphorylated at various residues are specific and sensitive to AD dementia. However, the currently available tests have shortcomings in access, throughput, and scalability that limit widespread implementation. Methods We evaluated the diagnostic and prognostic performance of a high-throughput and fully-automated Lumipulse plasma p-tau181 assay for the detection of AD. Plasma from older clinically unimpaired individuals (CU, n = 463) and patients with mild cognitive impairment (MCI, n = 107) or AD dementia (n = 78) were obtained from the longitudinal Stanford University Alzheimer’s Disease Research Center (ADRC) and the Stanford Aging and Memory Study (SAMS) cohorts. We evaluated the discriminative accuracy of plasma p-tau181 for clinical AD diagnosis, association with amyloid β peptides and p-tau181 concentrations in CSF, association with amyloid positron emission tomography (PET), and ability to predict longitudinal cognitive and functional change. Results The assay showed robust performance in differentiating AD from control participants (AUC 0.959, CI: 0.912 to 0.990), and was strongly associated with CSF p-tau181, CSF Aβ42/Aβ40 ratio, and amyloid-PET global SUVRs. Associations between plasma p-tau181 with CSF biomarkers were significant when examined separately in Aβ+ and Aβ− groups. Plasma p-tau181 significantly increased over time in CU and AD diagnostic groups. After controlling for clinical diagnosis, age, sex, and education, baseline plasma p-tau181 predicted change in MoCA overall and change in CDR Sum of Boxes in the AD group over follow-up of up to 5 years. Conclusions This fully-automated and available blood-based biomarker assay therefore may be useful for early detection, diagnosis, prognosis, and treatment monitoring of AD.

Besides the typical amnestic presentation, neuropathological studies indicate that Alzheimer's disease (AD) may present with atypical clinical pictures. The relative frequencies of typical and atypical or mixed presentations within the entire spectrum of AD remain unclear, while some mixed or atypical presentations may have not received adequate attention for them to be included in diagnostic criteria. We investigated the spectrum of clinical presentations in patients with the AD CSF biomarker profile (high tau and phospho-tau, low Aβ42 levels), hospitalized in a tertiary academic center. Among 98 patients with the CSF AD profile, 46% of patients had the typical presentation of "hippocampal" amnestic dementia. Additionally, 23.5% and 15.3% fulfilled the criteria of mixed or atypical presentations, respectively, as described in the IWG-2 criteria. The remaining 15.3% had unusual presentations, including non-logopenic (semantic and non-fluent agrammatic) primary progressive aphasia, corticobasal syndrome, and Richardson syndrome, or could be diagnosed with normal pressure hydrocephalus. Despite selection bias (academic center), atypical clinical presentations of AD may be more common than previously thought. CSF biomarkers seem to be a useful tool for antemortem identification of such patients, which is likely to affect therapeutic decisions. Some of the unusual presentations described above should be incorporated in diagnostic criteria. [ABSTRACT FROM AUTHOR]

Background: The recent promise of disease-modifying therapies for Alzheimer's disease (AD) has reinforced the need for accurate biomarkers for early disease detection, diagnosis and treatment monitoring. Advances in the development of novel blood-based biomarkers for AD have revealed that plasma levels of tau phosphorylated at various residues are specific and sensitive to AD dementia. However, the currently available tests have shortcomings in access, throughput, and scalability that limit widespread implementation. Methods: We evaluated the diagnostic and prognostic performance of a high-throughput and fully-automated Lumipulse plasma p-tau181 assay for the detection of AD. Plasma from older clinically unimpaired individuals (CU, n = 463) and patients with mild cognitive impairment (MCI, n = 107) or AD dementia (n = 78) were obtained from the longitudinal Stanford University Alzheimer's Disease Research Center (ADRC) and the Stanford Aging and Memory Study (SAMS) cohorts. We evaluated the discriminative accuracy of plasma p-tau181 for clinical AD diagnosis, association with amyloid β peptides and p-tau181 concentrations in CSF, association with amyloid positron emission tomography (PET), and ability to predict longitudinal cognitive and functional change. Results: The assay showed robust performance in differentiating AD from control participants (AUC 0.959, CI: 0.912 to 0.990), and was strongly associated with CSF p-tau181, CSF Aβ42/Aβ40 ratio, and amyloid-PET global SUVRs. Associations between plasma p-tau181 with CSF biomarkers were significant when examined separately in Aβ+ and Aβ− groups. Plasma p-tau181 significantly increased over time in CU and AD diagnostic groups. After controlling for clinical diagnosis, age, sex, and education, baseline plasma p-tau181 predicted change in MoCA overall and change in CDR Sum of Boxes in the AD group over follow-up of up to 5 years. Conclusions: This fully-automated and available blood-based biomarker assay therefore may be useful for early detection, diagnosis, prognosis, and treatment monitoring of AD. [ABSTRACT FROM AUTHOR]

Blood phospho-tau181 may offer a useful biomarker for Alzheimer's disease. However, the use of either serum or plasma phospho-tau181 and their diagnostic value are currently under intense investigation. In a pilot study, we measured both serum and plasma phospho-tau181 (pT181-Tau) by single molecule array (Simoa) in a group of patients with Alzheimer's disease and a mixed group of patients with other primary dementing and/or movement disorders. Classical cerebrospinal fluid biomarkers were also measured. Plasma (but not serum) pT181-Tau showed a significant increase in Alzheimer's disease and correlated significantly with cerebrospinal fluid amyloid and pT181-Tau. Receiver operating curve analysis revealed a significant discrimination of Alzheimer's from non-Alzheimer's disease patients, with an area under the curve of 0.83 and an excellent sensitivity but a moderate specificity. Plasma pT181-Tau is not an established diagnostic biomarker for Alzheimer's disease, but it could become one in the future, or it may serve as a screening tool for specific cases of patients or presymptomatic subjects. [ABSTRACT FROM AUTHOR]

Cerebrospinal fluid (CSF) biomarkers remain the gold standard for fluid-biomarker-based diagnosis of Alzheimer's disease (AD) during life. Plasma biomarkers avoid lumbar puncture and allow repeated sampling. Changes of plasma phospho-tau-181 in AD are of comparable magnitude and seem to parallel the changes in CSF, may occur in preclinical or predementia stages of the disease, and may differentiate AD from other causes of dementia with adequate accuracy. Plasma phospho-tau-181 may offer a useful alternative to CSF phospho-tau determination, but work still has to be done concerning the optimal method of determination with the highest combination of sensitivity and specificity and cost-effect parameters. [ABSTRACT FROM AUTHOR]

Inflammation is becoming increasingly recognized as an important contributor to Alzheimer's disease (AD) pathogenesis. As a part of the innate immune system, the complement cascade enhances the body's ability to destroy and remove pathogens and has recently been shown to influence Alzheimer's associated amyloid and tau pathology. However, little is known in humans about the effects of the complement system and genetic modifiers of AD risk like the ε4 allele of apolioprotein E (APOE ε4) on AD pathobiology. We evaluated cerebrospinal fluid (CSF) protein levels from 267 individuals clinically diagnosed as cognitively normal, mild cognitive impairment, and AD. Using linear models, we assessed the relationship between APOE ε4 genotype, CSF Complement 3 (C3), CSF amyloid-β (amyloid) and CSF hyperphosphorylated tau (ptau). We found a significant interaction between APOE ε4 and CSF C3 on both CSF amyloid and CSF ptau. We also found that CSF C3 is only associated with CSF ptau after accounting for CSF amyloid. Our results support a conceptual model of the AD pathogenic cascade where a synergistic relationship between the complement cascade (C3) and APOE ε4 results in elevated Alzheimer's neurodegeneration and in turn, amyloid further regulates the effect of the complement cascade on downstream tau pathology.

The use and interpretation of diagnostic cerebrospinal fluid (CSF) biomarkers for neurodegenerative disorders, such as Dementia with Lewy bodies (DLB), represent a clinical challenge. According to the literature, the composition of CSF in DLB patients varies. Some patients present with reduced levels of amyloid, others with full Alzheimer Disease CSF profile (both reduced amyloid and increased phospho-tau) and some with a normal profile. Some patients may present with abnormal levels of a-synuclein. Continuous efforts will be required to establish useful CSF biomarkers for the early diagnosis of DLB. Given the heterogeneity of methods and results between studies, further validation is fundamental before conclusions can be drawn. [ABSTRACT FROM AUTHOR]

Cerebrospinal fluid (CSF) biomarkers remain the gold standard for fluid-biomarker-based diagnosis of Alzheimer’s disease (AD) during life. Plasma biomarkers avoid lumbar puncture and allow repeated sampling. Changes of plasma phospho-tau-181 in AD are of comparable magnitude and seem to parallel the changes in CSF, may occur in preclinical or predementia stages of the disease, and may differentiate AD from other causes of dementia with adequate accuracy. Plasma phospho-tau-181 may offer a useful alternative to CSF phospho-tau determination, but work still has to be done concerning the optimal method of determination with the highest combination of sensitivity and specificity and cost-effect parameters.

Background and Objectives: The US Food and Drug Administration (FDA) defines a biomarker as a characteristic that is measured as an indicator of normal biological processes, pathogenic processes, or responses to an exposure or intervention. Biomarkers may be used in clinical care or as drug development tools (DDTs) in clinical trials. The goal of this review and perspective is to provide insight into the regulatory guidance for the use of biomarkers in clinical trials and clinical care. Materials and Methods: We reviewed FDA guidances relevant to biomarker use in clinical trials and their transition to use in clinical care. We identified instructive examples of these biomarkers in Alzheimer’s disease (AD) drug development and their application in clinical practice. Results: For use in clinical trials, biomarkers must have a defined context of use (COU) as a risk/susceptibility, diagnostic, monitoring, predictive, prognostic, pharmacodynamic, or safety biomarker. A four-stage process defines the pathway to establish the regulatory acceptance of the COU for a biomarker including submission of a letter of intent, description of the qualification plan, submission of a full qualification package, and acceptance through a qualification recommendation. Biomarkers used in clinical care may be companion biomarkers, in vitro diagnostic devices (IVDs), or laboratory developed tests (LDTs). A five-phase biomarker development process has been proposed to structure the biomarker development process. Conclusions: Biomarkers are increasingly important in drug development and clinical care. Adherence to regulatory guidance for biomarkers used in clinical trials and patient care is required to advance these important drug development and clinical tools.

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 (18F‐RO948). Results: Plasma phospho‐tau217 correlated with plasma phospho‐tau181, CSF phospho‐tau217 (rs = 0.68, P < 0.001), and negatively with CSF β‐amyloid42/40 (rs = −0.52, P = 0.001). Plasma phospho‐tau217 and phospho‐tau181 correlated with tau‐PET signal in the temporal cortex (rs > 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. [ABSTRACT FROM AUTHOR]

The use and interpretation of diagnostic cerebrospinal fluid (CSF) biomarkers for neurodegenerative disorders, such as Dementia with Lewy bodies (DLB), represent a clinical challenge. According to the literature, the composition of CSF in DLB patients varies. Some patients present with reduced levels of amyloid, others with full Alzheimer Disease CSF profile (both reduced amyloid and increased phospho-tau) and some with a normal profile. Some patients may present with abnormal levels of a-synuclein. Continuous efforts will be required to establish useful CSF biomarkers for the early diagnosis of DLB. Given the heterogeneity of methods and results between studies, further validation is fundamental before conclusions can be drawn.

Analysis of classical cerebrospinal fluid biomarkers, especially when incorporated in a classification/diagnostic system such as the AT(N), may offer a significant diagnostic tool allowing correct identification of Alzheimer’s disease during life. We describe four patients with more or less atypical or mixed clinical presentation, in which the classical cerebrospinal fluid biomarkers amyloid peptide with 42 and 40 amino acids (Aβ42 and Aβ40, respectively), phospho-tau (τP-181) and total tau (τΤ) were measured. Despite the unusual clinical presentation, the biomarker profile was compatible with Alzheimer’s disease in all four patients. The measurement of classical biomarkers in the cerebrospinal fluid may be a useful tool in identifying the biochemical fingerprints of Alzheimer’s disease, especially currently, due to the recent approval of the first disease-modifying treatment, allowing not only typical but also atypical cases to be enrolled in trials of such treatments.

Correct in vivo diagnosis of Alzheimer’s disease (AD) helps to avoid administration of disease-modifying treatments in non-AD patients, and allows the possible use of such treatments in clinically atypical AD patients. Cerebrospinal fluid (CSF) biomarkers offer a tool for AD diagnosis. A reduction in CSF β-amyloid (marker of amyloid plaque burden), although compatible with Alzheimer’s pathological change, may also be observed in other dementing disorders, including vascular cognitive disorders due to subcortical small-vessel disease, dementia with Lewy bodies and normal-pressure hydrocephalus. Thus, for the diagnosis of AD, an abnormal result of CSF β-amyloid may not be sufficient, and an increase in phospho-tau (marker of tangle pathology) is also required in order to confirm AD diagnosis in patients with a typical amnestic presentation and reveal underlying AD in patients with atypical or mixed and diagnostically confusing clinical presentations.

Abstract Background The progression of mild cognitive impairment (MCI) to Alzheimer’s disease (AD) dementia can be predicted by cognitive, neuroimaging, and cerebrospinal fluid (CSF) markers. Since most biomarkers reveal complementary information, a combination of biomarkers may increase the predictive power. We investigated which combination of the Mini-Mental State Examination (MMSE), Clinical Dementia Rating (CDR)-sum-of-boxes, the word list delayed free recall from the Consortium to Establish a Registry of Dementia (CERAD) test battery, hippocampal volume (HCV), amyloid-beta1–42 (Aβ42), amyloid-beta1–40 (Aβ40) levels, the ratio of Aβ42/Aβ40, phosphorylated tau, and total tau (t-Tau) levels in the CSF best predicted a short-term conversion from MCI to AD dementia. Methods We used 115 complete datasets from MCI patients of the “Dementia Competence Network”, a German multicenter cohort study with annual follow-up up to 3 years. MCI was broadly defined to include amnestic and nonamnestic syndromes. Variables known to predict progression in MCI patients were selected a priori. Nine individual predictors were compared by receiver operating characteristic (ROC) curve analysis. ROC curves of the five best two-, three-, and four-parameter combinations were analyzed for significant superiority by a bootstrapping wrapper around a support vector machine with linear kernel. The incremental value of combinations was tested for statistical significance by comparing the specificities of the different classifiers at a given sensitivity of 85%. Results Out of 115 subjects, 28 (24.3%) with MCI progressed to AD dementia within a mean follow-up period of 25.5 months. At baseline, MCI-AD patients were no different from stable MCI in age and gender distribution, but had lower educational attainment. All single biomarkers were significantly different between the two groups at baseline. ROC curves of the individual predictors gave areas under the curve (AUC) between 0.66 and 0.77, and all single predictors were statistically superior to Aβ40. The AUC of the two-parameter combinations ranged from 0.77 to 0.81. The three-parameter combinations ranged from AUC 0.80–0.83, and the four-parameter combination from AUC 0.81–0.82. None of the predictor combinations was significantly superior to the two best single predictors (HCV and t-Tau). When maximizing the AUC differences by fixing sensitivity at 85%, the two- to four-parameter combinations were superior to HCV alone. Conclusion A combination of two biomarkers of neurodegeneration (e.g., HCV and t-Tau) is not superior over the single parameters in identifying patients with MCI who are most likely to progress to AD dementia, although there is a gradual increase in the statistical measures across increasing biomarker combinations. This may have implications for clinical diagnosis and for selecting subjects for participation in clinical trials.

Background: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that still lacks reliable diagnostic biomarkers. This study aims to evaluate the diagnostic and prognostic potential of CSF total Tau (t-Tau), phospho-Tau (p-Tau) and p-Tau/t-Tau ratio in ALS patients using CSF neurofilament light (NFL) as the reference biomarker.Methods: Eighty-five incident ALS, 30 ALS-mimicking (AM) diseases and 51 other non-neurodegenerative diseases (ONND) were included in the study.Results: ALS patients had higher levels of CSF t-Tau and lower p-Tau/t-Tau ratio than AM (p = 0.005 and p = 0.006) and ONND (p < 0.001). CSF t-Tau levels discriminated ALS from AM with a sensitivity of 69% and specificity of 60%, and from ONND with a sensitivity of 88% and specificity of 51%. These values were lower than the accuracy of CSF NFL in ALS (sensitivity 86% and specificity 87% in distinguishing ALS from AM and sensitivity 83% and specificity 75% from ONND); CSF t-Tau correlated with progression rate and SNIP. CSF p-Tau did not show relation with any ALS clinical features. CSF NFL significantly correlated with all considered clinical parameters. High levels of CSF t-Tau and NFL were related to poor survival.Conclusion: CSF t-Tau showed no reliable diagnostic significance but the relation between the high levels of CSF t-Tau and short survival suggests the potential prognostic role of this biomarker in ALS. However, CSF NFL was confirmed to be the most reliable and efficient tool for diagnosis and prediction of clinical progression and survival in ALS patients. [ABSTRACT FROM AUTHOR]

Background: The progression of mild cognitive impairment (MCI) to Alzheimer's disease (AD) dementia can be predicted by cognitive, neuroimaging and cerebrospinal fluid (CSF) markers. Since most biomarkers reveal complementary information, a combination of biomarkers may increase the predictive power. We investigated which combination of the Mini-Mental State Examination (MMSE), Clinical Dementia Rating (CDR)-sum-of-boxes, the word list delayed free recall from the Consortium to Establish a Registry of Dementia (CERAD) test battery, hippocampal volume (HCV), amyloid-beta1-42 (Aβ42), amyloid-beta1-40 (Aβ40) levels, the ratio of Aβ42/Aβ40, phosphorylated tau and total tau (t-Tau) levels in the CSF best predicted a short-term conversion from MCI to AD dementia. Methods: We used 115 complete datasets from MCI patients of the "Dementia Competence Network", a German multicenter cohort study with annual follow-up up to 3 years. MCI was broadly defined to include amnestic and nonamnestic syndromes. Variables known to predict progression in MCI patients were selected a priori. Nine individual predictors were compared by receiver operating characteristic (ROC) curve analysis. ROC curves of the five best two-, three- and four-parameter combinations were analyzed for significant superiority by a bootstrapping wrapper around a support vector machine with linear kernel. The incremental value of combinations was tested for statistical significance by comparing the specificities of the different classifiers at a given sensitivity of 85%. Results: Out of 115 subjects, 28 (24.3%) with MCI progressed to AD dementia within a mean follow-up period of 25.5 months. At baseline, MCI-AD patients were no different from stable MCI in age and gender distribution, but had lower educational attainment. All single biomarkers were significantly different between the two groups at baseline. ROC curves of the individual predictors gave areas under the curve (AUC) between 0.66 and 0.77 and all single predictors were statistically superior to Aβ40. The AUC of the two-parameter combinations ranged from 0.77 to 0.81. The three-parameter combinations ranged from AUC 0.80-0.83 and the four-parameter combination from AUC 0.81-0.82. None of the predictor combinations was significantly superior to the two best single predictors (HCV and t-Tau). When maximizing the AUC differences by fixing sensitivity at 85%, the two- to four-parameter combinations were superior to HCV alone. Conclusion: A combination of two biomarkers of neurodegeneration (e.g., HCV and t-Tau) is not superior over the single parameters in identifying patients with MCI who are most likely to progress to AD dementia, although there is a gradual increase in the statistical measures across increasing biomarker combinations. This may have implications for clinical diagnosis and for selecting subjects for participation in clinical trials. [ABSTRACT FROM AUTHOR]

Background: Primary progressive aphasia (PPA) may present with three main clinical variants, namely nonfluent agrammatic (nfaPPA), semantic (sPPA), and logopenic (lPPA) subtypes. Frontotemporal lobar degenerations (FTLD) or Alzheimer's disease (AD) are the most common etiologies.Objective: To study the potential of cerebrospinal fluid (CSF) biomarkers for identifying the underlying pathology in patients with PPA.Methods: CSF levels of total tau protein (τT), amyloid-β peptide (Aβ42), and tau phosphorylated at threonine-181 (τP - 181) were measured by double sandwich, enzyme-linked immunosorbent assay (ELISA) in 43 patients with PPA, 26 patients with AD, and 17 healthy controls.Results: All patients could be classified as compatible with the AD or non-AD biomarker profile, either with the three biomarkers (90.7%) or their ratios, especially the τP - 181/Aβ42 ratio (9.3%). An AD-compatible biomarker profile was present in 39.5% of all PPA patients, specifically 22.2%, 35.7%, and 75% of nfaPPA, sPPA, and lPPA, respectively. In PPA patients with a non-AD profile (presumably FTLD), two different clusters could be identified according to the τP - 181/τT ratio, possibly corresponding to the two major FTLD pathologies (tau and TDP-43).Conclusion: CSF biomarkers may be a valuable tool for the discrimination between PPA patients with AD and non-AD pathophysiology and possibly between FTLD patients with tau and TDP-43 pathology. [ABSTRACT FROM AUTHOR]

Background: Proteinase-activated receptor 2 (PAR-2) has been shown to promote both neurotoxic and neuroprotective effects. Similarly, other routinely used nonspecific markers of neuronal damage can be found in cerebrospinal fluid (CSF) and can be used as biomarkers for different neurodegenerative disorders. Methods: Using enzyme-linked immunosorbent assays and western blotting we assessed PAR-2, total-tau, phospho-tau, beta-amyloid levels, and protein 14-3-3 in the CSF of former patients who had undergone a neuropathological autopsy after death and who had been definitively diagnosed with a prion or other neurodegenerative disease. Results: We did not find any significant correlation between levels of PAR-2 and other biomarkers, nor did we find any differences in PAR-2 levels between prion diseases and other neurodegenerative conditions. However, we confirmed that very high total-tau levels were significantly associated with definitive prion diagnoses and exhibited greater sensitivity and specificity than protein 14-3-3, which is routinely used as a marker. Conclusions: Our study showed that PAR-2, in CSF, was not specifically altered in prion diseases compared to other neurodegenerative conditions. Our results also confirmed that very high total-tau protein CSF levels were significantly associated with a definitive Creutzfeldt-Jakob disease (CJD) diagnosis and should be routinely tested as a diagnostic marker. Observed individual variability in CSF biomarkers provide invaluable feedback from neuropathological examinations even in "clinically certain" cases. [ABSTRACT FROM AUTHOR]

Background/Aims: Increased cerebrospinal fluid (CSF) tau, decreased CSF amyloid-β42 (Aβ42) and the apolipoprotein E gene (APOE) ε4 allele predict progression from mild cognitive impairment (MCI) to Alzheimer’s disease (AD). Here, we investigated these markers to assess their predictive value and influence on the rate of disease progression. Methods: Using ELISA, we measured the CSF biomarkers in 47 AD patients, 58 patients with MCI and 35 healthy control subjects. Twenty-eight MCI patients revisited the clinic and half of them progressed to AD during a period of 3–12 years. Results: The expected changes in CSF total (T)-tau, phosphorylated (P)-tau and Aβ42 levels were found in AD, confirming the diagnostic value of these biomarkers. We were also able to corroborate an increased risk for progression from MCI to AD with elevated CSF T-tau and P-tau and with the presence of the APOE ε4/ε4 genotype, but not with decreased Aβ42. Finally, for the first time we demonstrated that MCI subjects with high CSF T-tau or P-tau and APOE ε4 homozygosity progressed faster from MCI to AD. Conclusions: CSF T-tau and P-tau as well as the APOE ε4/ε4 genotype are robust predictors of AD and are also associated with a more rapid progression from MCI to AD. Copyright © 2009 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background and purpose: The differential diagnosis between vascular dementia (VD) and Alzheimer’s disease (AD) or mixed dementia (MD) is not always easy in clinical practice. The purpose of the present study was to evaluate the cerebrospinal fluid (CSF) biomarkers tau protein in its total (τT) or hyperphosphorylated at threonin-181(τP-181) form and beta amyloid peptide 1–42 (Aβ42) alone and their combinations to investigate their diagnostic value in the discrimination between VD and AD or MD. Methods: The above CSF biomarkers were determined in duplicate and blind to the clinical diagnosis by double sandwich, enzyme-linked immunosorbent assay (ELISA) commercial kits (Innogenetics, Gent, Belgium) in 92 AD patients, 23 VD patients, 17 patients with MD and 68 controls. Results: Alzheimer’s disease and MD showed increased levels of τT, τP and reduced levels of Aβ42 as compared with the controls. The best discrimination between VD and AD or MD was achieved by the combination of all three biomarkers, correctly classifying ≥85% of patients, either in the form of a discriminant function or in the form of the τT × τP-181/Aβ42 formula. Conclusions: Cerebrospinal fluid biomarkers may be a useful adjunct for the discrimination between AD/ MD and VD in every day clinical practice. [ABSTRACT FROM AUTHOR]

Abstract: To establish diagnostic performance of the cerebrospinal fluid (CSF) biomarkers β-amyloid peptide (Aβ1–42), total tau-protein (T-tau) and tau phosphorylated at threonine 181 (P-tau181P) compared to clinical diagnosis, biomarker levels were determined in CSF samples from 100 autopsy-confirmed dementia and 100 control subjects. As the control and dementia groups were not age-matched and given the significant associations of biomarker concentrations with age in controls, age-corrected biomarker concentrations were calculated. New models were constructed by means of logistic regression. Using all biomarkers, dementia could be discriminated from controls (sensitivity (S)=86%, specificity (Sp)=89%). T-tau and Aβ1–42 optimally discriminated Alzheimer''s disease (AD) from other dementias (NONAD) and controls (S =90%, Sp=89%). AD was optimally discriminated from NONAD using P-tau181P and Aβ1–42 (S =80%, Sp=93%). Diagnostic accuracy of the latter model (82.7%) was comparable to clinical diagnostic accuracy (81.6%) that was based on a whole clinical work-up (including imaging). Using this model, in cases with clinically doubtful diagnoses, a correct diagnosis would have been established in 4/6 autopsy-confirmed AD and 3/3 autopsy-confirmed NONAD cases. The value of biomarkers in differential dementia diagnosis was shown, using pathological diagnosis as a reference. New models have been developed, achieving sensitivity, specificity and diagnostic accuracy levels, consistently exceeding 80%. [Copyright &y& Elsevier]

Biomarkers to monitor the degenerative process in Alzheimer''s disease would be of great value. We examined the relation between cerebrospinal fluid (CSF) total tau (T-tau), phospho-tau (P-tau) and Aβ42 and magnetic resonance imaging (MRI) measures of brain atrophy. CSF was taken at baseline and MRI at baseline and at 16 months follow-up. At baseline, statistically significantly lower Aβ42 were found with lower brain volume (r=0.55; P<0.0001) and larger ventricular volume (r=−0.53; P<0.001). In contrast, statistically significantly higher T-tau (r=0.47; P<0.001) and P-tau (r=0.41; P=0.005) were found with more marked ventricular widening during the follow-up period. These results suggest that Aβ42 in CSF reflects the stage of the disease, with lower CSF levels as the disease progresses, while T-tau and P-tau reflect the intensity of the disease process, with higher CSF-levels with a more rapid progression. [Copyright &y& Elsevier]

Analysis of classical cerebrospinal fluid biomarkers, especially when incorporated in a classification/diagnostic system such as the AT(N), may offer a significant diagnostic tool allowing correct identification of Alzheimer's disease during life. We describe four patients with more or less atypical or mixed clinical presentation, in which the classical cerebrospinal fluid biomarkers amyloid peptide with 42 and 40 amino acids (Aβ42 and Aβ40, respectively), phospho-tau (τP-181) and total tau (τΤ) were measured. Despite the unusual clinical presentation, the biomarker profile was compatible with Alzheimer's disease in all four patients. The measurement of classical biomarkers in the cerebrospinal fluid may be a useful tool in identifying the biochemical fingerprints of Alzheimer's disease, especially currently, due to the recent approval of the first disease-modifying treatment, allowing not only typical but also atypical cases to be enrolled in trials of such treatments. [ABSTRACT FROM AUTHOR]

Correct in vivo diagnosis of Alzheimer's disease (AD) helps to avoid administration of disease-modifying treatments in non-AD patients, and allows the possible use of such treatments in clinically atypical AD patients. Cerebrospinal fluid (CSF) biomarkers offer a tool for AD diagnosis. A reduction in CSF β-amyloid (marker of amyloid plaque burden), although compatible with Alzheimer's pathological change, may also be observed in other dementing disorders, including vascular cognitive disorders due to subcortical small-vessel disease, dementia with Lewy bodies and normal-pressure hydrocephalus. Thus, for the diagnosis of AD, an abnormal result of CSF β-amyloid may not be sufficient, and an increase in phospho-tau (marker of tangle pathology) is also required in order to confirm AD diagnosis in patients with a typical amnestic presentation and reveal underlying AD in patients with atypical or mixed and diagnostically confusing clinical presentations. [ABSTRACT FROM AUTHOR]

A major diagnostic challenge when people seek advice for cognitive dysfunction is to differentiate between mild cognitive impairment (MCI) and incipient Alzheimer''s disease (AD). We show that a combination of three cerebrospinal fluid biochemical markers, total-tau, phospho-tau and β-amyloid(1-42), can detect incipient AD among patients fulfilling the criteria for MCI with a sensitivity of 68% (95% CI 45–86%) and a specificity of 97% (95% CI 83–100%). The usefulness of these markers is further emphasized by the finding of a positive predictive value of 94% and a negative predictive value of 81%. [Copyright &y& Elsevier]