| 41. |
- Björkqvist, Maria, et al.
(författare)
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Evaluation of a previously suggested plasma biomarker panel to identify Alzheimer's disease.
- 2012
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- There is an urgent need for biomarkers in plasma to identify Alzheimer's disease (AD). It has previously been shown that a signature of 18 plasma proteins can identify AD during pre-dementia and dementia stages (Ray et al, Nature Medicine, 2007). We quantified the same 18 proteins in plasma from 174 controls, 142 patients with AD, and 88 patients with other dementias. Only three of these proteins (EGF, PDG-BB and MIP-1δ) differed significantly in plasma between controls and AD. The 18 proteins could classify patients with AD from controls with low diagnostic precision (area under the ROC curve was 63%). Moreover, they could not distinguish AD from other dementias. In conclusion, independent validation of results is important in explorative biomarker studies.
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| 42. |
- Blennow, Kaj, 1958, et al.
(författare)
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Amyloid biomarkers in Alzheimer's disease.
- 2015
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Ingår i: Trends in pharmacological sciences. - : Elsevier BV. - 1873-3735 .- 0165-6147. ; 36:5, s. 297-309
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Tidskriftsartikel (refereegranskat)abstract
- Aggregation of amyloid-β (Aβ) into oligomers, fibrils, and plaques is central in the molecular pathogenesis of Alzheimer's disease (AD), and is the main focus of AD drug development. Biomarkers to monitor Aβ metabolism and aggregation directly in patients are important for further detailed study of the involvement of Aβ in disease pathogenesis and to monitor the biochemical effect of drugs targeting Aβ in clinical trials. Furthermore, if anti-Aβ disease-modifying drugs prove to be effective clinically, amyloid biomarkers will be of special value in the clinic to identify patients with brain amyloid deposition at risk for progression to AD dementia, to enable initiation of treatment before neurodegeneration is too severe, and to monitor drug effects on Aβ metabolism or pathology to guide dosage. Two types of amyloid biomarker have been developed: Aβ-binding ligands for use in positron emission tomography (PET) and assays to measure Aβ42 in cerebrospinal fluid (CSF). In this review, we present the rationales behind these biomarkers and compare their ability to measure Aβ plaque load in the brain. We also review possible shortcomings and the need of standardization of both biomarkers, as well as their implementation in the clinic.
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| 43. |
- Blennow, Kaj, et al.
(författare)
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Blodtest – fönster till hjärnan vid Alzheimers sjukdom
- 2024
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Ingår i: Lakartidningen. - 0023-7205. ; 121
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Forskningsöversikt (refereegranskat)abstract
- Technical developments have paved the way for the development of ultrasensitive analytical methods that allow for precise quantification of brain-specific proteins in blood samples. Plasma levels of amyloid β, specifically the Aβ42/40 ratio, are reduced in Alzheimer's disease (AD) and show concordance with brain amyloidosis assessed by PET, but the overlap with normal elderly may be too large for reliable use in clinical applications. Plasma phosphorylated tau (P-tau), especially a variant called P-tau217, is markedly increased in the early symptomatic stages of AD but remains normal in other neurodegenerative disorders. Total tau (T-tau) is measurable in blood and shows most promise as a biomarker for acute neuronal injury (e.g. acute traumatic or hypoxic brain injury), where T-tau shows a fast and dramatic increase but does not work well as an AD biomarker due to contributions to blood levels from peripheral tissues. Instead, a novel method for tau protein produced only in the CNS called brain-derived tau (BD-tau) shows promise as a biomarker for AD-type neurodegeneration. Neurofilament light (NFL) levels in blood correlate tightly with levels in CSF and reflect axonal injury irrespective of the underlying cause. Increased blood NFL concentration is found in several neurodegenerative disorders, including AD, but even more so in disorders such as motor neuron disease and frontotemporal dementia. Glial fibrillary acidic protein (GFAP) is expressed with activation of astrocytes, and is mildly increased in AD, but is also very high also in acute brain disorders. These blood tests show promise as tools to identify AD pathophysiology in the first assessment of patients with early cognitive symptoms, also in primary care, to guide clinical management and possible admission to the specialist clinic. A two-step model will result in a very high accuracy to either predict or exclude brain amyloidosis of the Alzheimer type.
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| 44. |
- Blennow, Kaj, et al.
(författare)
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Cerebrospinal fluid tau fragment correlates with tau PET : a candidate biomarker for tangle pathology
- 2020
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Ingår i: Brain : a journal of neurology. - : Oxford University Press (OUP). - 1460-2156. ; 143:2, s. 650-660
-
Tidskriftsartikel (refereegranskat)abstract
- To date, there is no validated fluid biomarker for tau pathology in Alzheimer's disease, with contradictory results from studies evaluating the correlation between phosphorylated tau in CSF with tau PET imaging. Tau protein is subjected to proteolytic processing into fragments before being secreted to the CSF. A recent study suggested that tau cleavage after amino acid 368 by asparagine endopeptidase (AEP) is upregulated in Alzheimer's disease. We used immunoprecipitation followed by mass spectrometric analyses to evaluate the presence of tau368 species in CSF. A novel Simoa® assay for quantification of tau368 in CSF was developed, while total tau (t-tau) was measured by ELISA and the presence of tau368 in tangles was evaluated using immunohistochemistry. The diagnostic utility of tau368 was first evaluated in a pilot study (Alzheimer's disease = 20, control = 20), then in a second cohort where the IWG-2 biomarker criteria were applied (Alzheimer's disease = 37, control = 45), and finally in a third cohort where the correlation with 18F-GTP1 tau PET was evaluated (Alzheimer's disease = 38, control = 11). The tau368/t-tau ratio was significantly decreased in Alzheimer's disease (P < 0.001) in all cohorts. Immunohistochemical staining demonstrated that tau fragments ending at 368 are present in tangles. There was a strong negative correlation between the CSF tau368/t-tau ratio and 18F-GTP1 retention. Our data suggest that tau368 is a tangle-enriched fragment and that the CSF ratio tau368/t-tau reflects tangle pathology. This novel tau biomarker could be used to improve diagnosis of Alzheimer's disease and to facilitate the development of drug candidates targeting tau pathology. Furthermore, future longitudinal studies will increase our understanding of tau pathophysiology in Alzheimer's disease and other tauopathies.
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| 45. |
- Blennow, K., et al.
(författare)
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EVOLUTION OF A beta 42 AND A beta 40 LEVELS AND A beta 42/A beta 40 RATIO IN PLASMA DURING PROGRESSION OF ALZHEIMER'S DISEASE: A MULTICENTER ASSESSMENT
- 2009
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Ingår i: Journal Of Nutrition Health & Aging. - 1279-7707. ; 13:3, s. 205-208
-
Konferensbidrag (refereegranskat)abstract
- Objective: To better understand the seemingly contradictory plasma beta-amyloid (A beta) results in Alzheimer's disease (AD) patients by using a newly developed plasma A beta assay, the INNO-BIA plasma A beta forms, in a multicenter study. Methods: A combined retrospective analysis of plasma A beta isoforms on mild cognitive impairment (MCI) from three large cross-sectional studies involving 643 samples from the participating German and Swedish centers. Results: Detection modules based on two different amino (N)-terminal specific A beta monoclonal antibodies demonstrated that A beta in plasma could be reliable quantified using a sandwich immunoassay technology with high precision, even for low A beta 42 plasma concentrations. A beta 40 and A beta 42 concentrations varied consistently with the ApoE genotype, while the A beta 42/A beta 40 ratio did not. Irrespective of the decrease of the A beta 42/A beta 40 ratio with age and MMSE, this parameter was strongly associated with AD, as defined in this study by elevated hyperphosphorylated (P-tau181P) levels in cerebrospinal fluid (CSF). Conclusion: A highly robust assay for repeatedly measuring A beta forms in plasma such as INNO-BIA plasma A beta forms might be a useful tool in a future risk assessment of AD.
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| 46. |
- Blennow, Kaj, 1958, et al.
(författare)
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Predicting clinical decline and conversion to Alzheimer's disease or dementia using novel Elecsys Aβ(1-42), pTau and tTau CSF immunoassays.
- 2019
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Ingår i: Scientific reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- We evaluated the performance of CSF biomarkers for predicting risk of clinical decline and conversion to dementia in non-demented patients with cognitive symptoms. CSF samples from patients in two multicentre longitudinal studies (ADNI, n=619; BioFINDER, n=431) were analysed. Aβ(1-42), tTau and pTau CSF concentrations were measured using Elecsys CSF immunoassays, and tTau/Aβ(1-42) and pTau/Aβ(1-42) ratios calculated. Patients were classified as biomarker (BM)-positive or BM-negative at baseline. Ability of biomarkers to predict risk of clinical decline and conversion to AD/dementia was assessed using pre-established cut-offs for Aβ(1-42) and ratios; tTau and pTau cut-offs were determined. BM-positive patients showed greater clinical decline than BM-negative patients, demonstrated by greater decreases in MMSE scores (all biomarkers: -2.10 to -0.70). Risk of conversion to AD/dementia was higher in BM-positive patients (HR: 1.67to11.48). Performance of Tau/Aβ(1-42) ratios was superior to single biomarkers, and consistent even when using cut-offs derived in a different cohort. Optimal pTau and tTau cut-offs were approximately 27pg/mL and 300pg/mL in both BioFINDER and ADNI. Elecsys pTau/Aβ(1-42) and tTau/Aβ(1-42) are robust biomarkers for predicting risk of clinical decline and conversion to dementia in non-demented patients, and may support AD diagnosis in clinical practice.
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| 47. |
- Blennow, Kaj, 1958, et al.
(författare)
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Second-generation Elecsys cerebrospinal fluid immunoassays aid diagnosis of early Alzheimer's disease.
- 2023
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Ingår i: Clinical chemistry and laboratory medicine. - : Walter de Gruyter GmbH. - 1437-4331 .- 1434-6621. ; 61:2, s. 234-244
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Tidskriftsartikel (refereegranskat)abstract
- Timely diagnosis of Alzheimer's disease (AD) is critical for appropriate treatment/patient management. Cerebrospinal fluid (CSF) biomarker analysis is often used to aid diagnosis. We assessed analytical performance of second-generation (Gen II) Elecsys® CSF immunoassays (Roche Diagnostics International Ltd), and adjusted existing cut-offs, to evaluate their potential utility in clinical routine.Analytical performance was assessed using CSF samples measured with Elecsys CSF Gen II immunoassays on cobas e analyzers. Aβ42 Gen I/Gen II immunoassay method comparisons were performed (Passing-Bablok regression). Cut-off values were adjusted using estimated bias in biomarker levels between BioFINDER protocol aliquots/Gen I immunoassays and Gen II protocol aliquots/immunoassays. Distribution of Gen II immunoassay values was evaluated in AD, mild cognitive impairment (MCI), and cognitively normal cohorts; percentage observations outside the measuring range were derived.The Gen II immunoassays demonstrated good analytical performance, including repeatability, intermediate precision, lot-to-lot agreement (Pearson's r:≥0.999), and platform agreement (Pearson's r:≥0.995). Aβ42 Gen I/Gen II immunoassay measurements were strongly correlated (Pearson's r: 0.985-0.999). Aβ42 Gen II immunoassay cut-offs were adjusted to 1,030 and 800ng/L, and pTau181/Aβ42 ratio cut-offs to 0.023 and 0.029, for Gen II and I protocols, respectively. No observations were below the lower limit of the measuring range; above the upper limit, there were none from the AD cohort, and 2.6 and 6.8% from the MCI and cognitively normal cohorts, respectively.Our findings suggest that the Gen II immunoassays have potential utility in clinical routine to aid diagnosis of AD.
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| 48. |
- Bocancea, Diana I., et al.
(författare)
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Determinants of cognitive and brain resilience to tau pathology: a longitudinal analysis
- 2023
-
Ingår i: Brain. - : Oxford University Press (OUP). - 0006-8950 .- 1460-2156. ; 146:9, s. 3719-3734
-
Tidskriftsartikel (refereegranskat)abstract
- Mechanisms of resilience against tau pathology in individuals across the Alzheimer’s disease spectrum are insufficiently understood. Longitudinal data are necessary to reveal which factors relate to preserved cognition (i.e. cognitive resilience) and brain structure (i.e. brain resilience) despite abundant tau pathology, and to clarify whether these associations are cross-sectional or longitudinal. We employed a longitudinal study design to investigate the role of several demographic, biological and brain structural factors in yielding cognitive and brain resilience to tau pathology as measured with PET.In this multicenter study, we included 366 amyloid-β-positive individuals with mild cognitive impairment or Alzheimer’s disease-dementia with baseline [18F]flortaucipir-PET and longitudinal cognitive assessments. A subset (n = 200) additionally underwent longitudinal structural MRI. We used linear mixed-effects models with global cognition and cortical thickness as dependent variables to investigate determinants of cognitive resilience and brain resilience, respectively. Models assessed whether age, sex, years of education, APOE-ε4 status, intracranial volume (and cortical thickness for cognitive resilience models) modified the association of tau pathology with cognitive decline or cortical thinning.We found that the association between higher baseline tau-PET levels (quantified in a temporal meta-region of interest) and rate of cognitive decline (measured with repeated Mini-Mental State Examination) was adversely modified by older age (Stβinteraction = -0.062, P = 0.032), higher education level (Stβinteraction = -0.072, P = 0.011) and higher intracranial volume (Stβinteraction = -0.07, P = 0.016). Younger age, higher education and greater cortical thickness were associated with better cognitive performance at baseline. Greater cortical thickness was furthermore associated with slower cognitive decline independent of tau burden. Higher education also modified the negative impact of tau-PET on cortical thinning, while older age was associated with higher baseline cortical thickness and slower rate of cortical thinning independent of tau. Our analyses revealed no (cross-sectional or longitudinal) associations for sex and APOE-ε4 status on cognition and cortical thickness.In this longitudinal study of clinically impaired individuals with underlying Alzheimer’s disease neuropathological changes, we identified education as the most robust determinant of both cognitive and brain resilience against tau pathology. The observed interaction with tau burden on cognitive decline suggests that education may be protective against cognitive decline and brain atrophy at lower levels of tau pathology, with a potential depletion of resilience resources with advancing pathology. Finally, we did not find major contributions of sex to brain nor cognitive resilience, suggesting that previous links between sex and resilience might be mainly driven by cross-sectional differences.
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| 49. |
- Boccardi, M., et al.
(författare)
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The strategic biomarker roadmap for the validation of Alzheimer's diagnostic biomarkers: methodological update
- 2021
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Ingår i: European Journal of Nuclear Medicine and Molecular Imaging. - : Springer Science and Business Media LLC. - 1619-7070 .- 1619-7089. ; 48, s. 2070-2085
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Tidskriftsartikel (refereegranskat)abstract
- Background The 2017 Alzheimer's disease (AD) Strategic Biomarker Roadmap (SBR) structured the validation of AD diagnostic biomarkers into 5 phases, systematically assessing analytical validity (Phases 1-2), clinical validity (Phases 3-4), and clinical utility (Phase 5) through primary and secondary Aims. This framework allows to map knowledge gaps and research priorities, accelerating the route towards clinical implementation. Within an initiative aimed to assess the development of biomarkers of tau pathology, we revised this methodology consistently with progress in AD research. Methods We critically appraised the adequacy of the 2017 Biomarker Roadmap within current diagnostic frameworks, discussed updates at a workshop convening the Alzheimer's Association and 8 leading AD biomarker research groups, and detailed the methods to allow consistent assessment of aims achievement for tau and other AD diagnostic biomarkers. Results The 2020 update applies to all AD diagnostic biomarkers. In Phases 2-3, we admitted a greater variety of study designs (e.g., cross-sectional in addition to longitudinal) and reference standards (e.g., biomarker confirmation in addition to clinical progression) based on construct (in addition to criterion) validity. We structured a systematic data extraction to enable transparent and formal evidence assessment procedures. Finally, we have clarified issues that need to be addressed to generate data eligible to evidence-to-decision procedures. Discussion This revision allows for more versatile and precise assessment of existing evidence, keeps up with theoretical developments, and helps clinical researchers in producing evidence suitable for evidence-to-decision procedures. Compliance with this methodology is essential to implement AD biomarkers efficiently in clinical research and diagnostics.
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| 50. |
- Bogdanovic, Nenad, et al.
(författare)
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[Alzheimer's disease - the most common cause of dementia]. : Alzheimers sjukdom – diagnostik och behandling i dag och i framtiden.
- 2020
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Ingår i: Lakartidningen. - 1652-7518. ; 117
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimer's disease is the most common cause of dementia. As many as 250,000 people in Sweden will have a dementia disease in 2050. The »amyloid cascade hypothesis« is a common model which explains how β-amyloid affects the function of the nerve cells. Alzheimer's disease has a long-lasting course and can present in typical and atypical forms. CSF analyses for »core AD CSF biomarkers« and synaptic proteins have been available for clinical diagnostics. PET scanning can detect either β-amyloid or tau aggregates in the brain of living humans. Current Alzheimer's disease therapy is based on two classes of cognition-enhancing drugs: acetylcholinesterase inhibitor and NMDA-receptor antagonist, which delays cognitive decline in most patients. The latest clinical development of potential therapy for Alzheimer's is active or passive immunotherapy against brain β-amyloid and tau, where several studies have shown varying but promising treatment effects. Non-pharmacological interventions in patients with AD aim to delay the loss of mental abilities, helping people to be independent in everyday life for as long as possible, and to increase their well-being and quality of life.
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