| 1. |
- Bartlett, Jonathan W, et al.
(författare)
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Determining cut-points for Alzheimer's disease biomarkers: statistical issues, methods and challenges.
- 2012
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Ingår i: Biomarkers in medicine. - : Future Medicine Ltd. - 1752-0371 .- 1752-0363. ; 6:4, s. 391-400
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Tidskriftsartikel (refereegranskat)abstract
- New proposed criteria for the clinical diagnosis of Alzheimer's disease increasingly incorporate biomarkers, most of which are normally measured on a continuous scale. Operationalizing such criteria thus requires continuous biomarkers to be dichotomized, which in turns requires the selection of a cut-point at which to dichotomize. In this article, we review the statistical principles underlying the choice of cut-points, describe some of the most commonly adopted statistical approaches used to estimate cut-points, highlight potential pitfalls in some of the approaches and characterize in what sense the estimated cut-point from each approach is optimal. We also emphasize that how a cut-point is selected must be made in reference to how the resulting dichotomized biomarker is to be used, and in particular what actions will follow from a positive or negative test result.
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| 2. |
- Bridel, Claire, et al.
(författare)
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Diagnostic Value of Cerebrospinal Fluid Neurofilament Light Protein in Neurology : A Systematic Review and Meta-analysis
- 2019
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Ingår i: JAMA Neurology. - : American Medical Association (AMA). - 2168-6149 .- 2168-6157. ; 76:9, s. 1035-1048
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Forskningsöversikt (refereegranskat)abstract
- Importance Neurofilament light protein (NfL) is elevated in cerebrospinal fluid (CSF) of a number of neurological conditions compared with healthy controls (HC) and is a candidate biomarker for neuroaxonal damage. The influence of age and sex is largely unknown, and levels across neurological disorders have not been compared systematically to date.Objectives To assess the associations of age, sex, and diagnosis with NfL in CSF (cNfL) and to evaluate its potential in discriminating clinically similar conditions.Data Sources PubMed was searched for studies published between January 1, 2006, and January 1, 2016, reporting cNfL levels (using the search terms neurofilament light and cerebrospinal fluid) in neurological or psychiatric conditions and/or in HC.Study Selection Studies reporting NfL levels measured in lumbar CSF using a commercially available immunoassay, as well as age and sex.Data Extraction and Synthesis Individual-level data were requested from study authors. Generalized linear mixed-effects models were used to estimate the fixed effects of age, sex, and diagnosis on log-transformed NfL levels, with cohort of origin modeled as a random intercept.Main Outcome and Measure The cNfL levels adjusted for age and sex across diagnoses.Results Data were collected for 10 059 individuals (mean [SD] age, 59.7 [18.8] years; 54.1% female). Thirty-five diagnoses were identified, including inflammatory diseases of the central nervous system (n = 2795), dementias and predementia stages (n = 4284), parkinsonian disorders (n = 984), and HC (n = 1332). The cNfL was elevated compared with HC in a majority of neurological conditions studied. Highest levels were observed in cognitively impaired HIV-positive individuals (iHIV), amyotrophic lateral sclerosis, frontotemporal dementia (FTD), and Huntington disease. In 33.3% of diagnoses, including HC, multiple sclerosis, Alzheimer disease (AD), and Parkinson disease (PD), cNfL was higher in men than women. The cNfL increased with age in HC and a majority of neurological conditions, although the association was strongest in HC. The cNfL overlapped in most clinically similar diagnoses except for FTD and iHIV, which segregated from other dementias, and PD, which segregated from atypical parkinsonian syndromes.Conclusions and Relevance These data support the use of cNfL as a biomarker of neuroaxonal damage and indicate that age-specific and sex-specific (and in some cases disease-specific) reference values may be needed. The cNfL has potential to assist the differentiation of FTD from AD and PD from atypical parkinsonian syndromes.
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| 3. |
- Lautner, Ronald, et al.
(författare)
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Preclinical effects of APOE ϵ4 on cerebrospinal fluid Aβ42 concentrations
- 2017
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Ingår i: Alzheimer's Research and Therapy. - : Springer Science and Business Media LLC. - 1758-9193. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: From earlier studies it is known that the APOE ϵ2/ϵ3/ϵ4 polymorphism modulates the concentrations of cerebrospinal fluid (CSF) beta-amyloid1-42 (Aβ42) in patients with cognitive decline due to Alzheimer's disease (AD), as well as in cognitively healthy controls. Here, in a large cohort consisting solely of cognitively healthy individuals, we aimed to evaluate how the effect of APOE on CSF Aβ42 varies by age, to understand the association between APOE and the onset of preclinical AD. Methods: APOE genotype and CSF Aβ42 concentration were determined in a cohort comprising 716 cognitively healthy individuals aged 17-99 from nine different clinical research centers. Results: CSF concentrations of Aβ42 were lower in APOE ϵ4 carriers than in noncarriers in a gene dose-dependent manner. The effect of APOE ϵ4 on CSF Aβ42 was age dependent. The age at which CSF Aβ42 concentrations started to decrease was estimated at 50 years in APOE ϵ4-negative individuals and 43 years in heterozygous APOE ϵ4 carriers. Homozygous APOE ϵ4 carriers showed a steady decline in CSF Aβ42 concentrations with increasing age throughout the examined age span. Conclusions: People possessing the APOE ϵ4 allele start to show a decrease in CSF Aβ42 concentration almost a decade before APOE ϵ4 noncarriers already in early middle age. Homozygous APOE ϵ4 carriers might deposit Aβ42 throughout the examined age span. These results suggest that there is an APOE ϵ4-dependent period of early alterations in amyloid homeostasis, when amyloid slowly accumulates, that several years later, together with other downstream pathological events such as tau pathology, translates into cognitive decline.
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| 4. |
- Portelius, Erik, 1977, et al.
(författare)
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Cerebrospinal fluid neurogranin: relation to cognition and neurodegeneration in Alzheimer's disease.
- 2015
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Ingår i: Brain : a journal of neurology. - : Oxford University Press (OUP). - 1460-2156 .- 0006-8950. ; 138, s. 3373-3385
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Tidskriftsartikel (refereegranskat)abstract
- Synaptic dysfunction is linked to cognitive symptoms in Alzheimer's disease. Thus, measurement of synapse proteins in cerebrospinal fluid may be useful biomarkers to monitor synaptic degeneration. Cerebrospinal fluid levels of the postsynaptic protein neurogranin are increased in Alzheimer's disease, including in the predementia stage of the disease. Here, we tested the performance of cerebrospinal fluid neurogranin to predict cognitive decline and brain injury in the Alzheimer's Disease Neuroimaging Initiative study. An in-house immunoassay was used to analyse neurogranin in cerebrospinal fluid samples from a cohort of patients who at recruitment were diagnosed as having Alzheimer's disease with dementia (n = 95) or mild cognitive impairment (n = 173), as well as in cognitively normal subjects (n = 110). Patients with mild cognitive impairment were grouped into those that remained cognitively stable for at least 2 years (stable mild cognitive impairment) and those who progressed to Alzheimer's disease dementia during follow-up (progressive mild cognitive impairment). Correlations were tested between baseline cerebrospinal fluid neurogranin levels and baseline and longitudinal cognitive impairment, brain atrophy and glucose metabolism within each diagnostic group. Cerebrospinal fluid neurogranin was increased in patients with Alzheimer's disease dementia (P < 0.001), progressive mild cognitive impairment (P < 0.001) and stable mild cognitive impairment (P < 0.05) compared with controls, and in Alzheimer's disease dementia (P < 0.01) and progressive mild cognitive impairment (P < 0.05) compared with stable mild cognitive impairment. In the mild cognitive impairment group, high baseline cerebrospinal fluid neurogranin levels predicted cognitive decline as reflected by decreased Mini-Mental State Examination (P < 0.001) and increased Alzheimer's Disease Assessment Scale-cognitive subscale (P < 0.001) scores at clinical follow-up. In addition, high baseline cerebrospinal fluid neurogranin levels in the mild cognitive impairment group correlated with longitudinal reductions in cortical glucose metabolism (P < 0.001) and hippocampal volume (P < 0.001) at clinical follow-up. Furthermore, within the progressive mild cognitive impairment group, elevated cerebrospinal fluid neurogranin levels were associated with accelerated deterioration in Alzheimer's Disease Assessment Scale-cognitive subscale (β = 0.0017, P = 0.01). These data demonstrate that cerebrospinal fluid neurogranin is increased already at the early clinical stage of Alzheimer's disease and predicts cognitive deterioration and disease-associated changes in metabolic and structural biomarkers over time.
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| 5. |
- Rosén, Christoffer, 1986, et al.
(författare)
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Benchmarking biomarker-based criteria for Alzheimer's disease : Data from the Swedish Dementia Registry, SveDem.
- 2015
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Ingår i: Alzheimer's & Dementia. - : Elsevier. - 1552-5260 .- 1552-5279. ; 11:12, s. 1470-1479
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: New research guidelines for the diagnosis of Alzheimer's disease (AD) include biomarker evidence of amyloid-β (Aβ) and tau pathology. The aim of this study was to investigate what proportion of AD patients diagnosed in clinical routine in Sweden that had an AD-indicative cerebrospinal fluid (CSF) biomarker profile.METHODS: By cross-referencing a laboratory database with the Swedish Dementia Registry (SveDem), 2357 patients with data on CSF Aβ and tau biomarkers and a clinical diagnosis of AD with dementia were acquired.RESULTS: Altogether, 77.2% had pathologic Aβ42 and total tau or phosphorylated tau in CSF. These results were stable across age groups. Female sex and low mini-mental state examination score increased the likelihood of pathologic biomarkers.DISCUSSION: About a quarter of clinically diagnosed AD patients did not have an AD-indicative CSF biomarker profile. This discrepancy may partly reflect incorrect (false positive) clinical diagnosis or a lack in sensitivity of the biomarker assays.
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| 6. |
- Skillbäck, Tobias, et al.
(författare)
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A novel quantification-driven proteomic strategy identifies an endogenous peptide of pleiotrophin as a new biomarker of Alzheimer's disease
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- We present a new, quantification-driven proteomic approach to identifying biomarkers. In contrast to the identification-driven approach, limited in scope to peptides that are identified by database searching in the first step, all MS data are considered to select biomarker candidates. The endopeptidome of cerebrospinal fluid from 40 Alzheimer's disease (AD) patients, 40 subjects with mild cognitive impairment, and 40 controls with subjective cognitive decline was analyzed using multiplex isobaric labeling. Spectral clustering was used to match MS/MS spectra. The top biomarker candidate cluster (215% higher in AD compared to controls, area under ROC curve = 0.96) was identified as a fragment of pleiotrophin located near the protein's C-terminus. Analysis of another cohort (n = 60 over four clinical groups) verified that the biomarker was increased in AD patients while no change in controls, Parkinson's disease or progressive supranuclear palsy was observed. The identification of the novel biomarker pleiotrophin 151-166 demonstrates that our quantification-driven proteomic approach is a promising method for biomarker discovery, which may be universally applicable in clinical proteomics.
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| 7. |
- Skillbäck, Tobias, et al.
(författare)
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Apolipoprotein E genotypes and longevity across dementia disorders
- 2018
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Ingår i: Alzheimer's & Dementia. - : Elsevier. - 1552-5260 .- 1552-5279. ; 14:7, s. 895-901
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: The ε4 allele of the apolipoprotein E (APOE) gene is a prominent risk factor for Alzheimer's disease (AD), but its implication in other dementias is less well studied.METHODS: We used a data set on 2858 subjects (1098 AD, 260 vascular dementia [VaD], 145 mixed AD and VaD, 90 other dementia diagnoses, and 1265 controls) to examine the association of APOE polymorphisms with clinical dementia diagnoses, biomarker profiles, and longevity.RESULTS: The ε4 allele was associated with reduced longevity as ε4 versus ε3 homozygotes lived on average 2.6 years shorter (P = .006). In AD, ε4 carriers lived 1.0 years shorter than noncarriers (P = .028). The ε4 allele was more prevalent in AD, mixed AD and VaD, and VaD patients compared to controls, but not in other dementia disorders.DISCUSSION: The APOE ε4 allele is influential in AD but might also be of importance in VaD and in mixed AD and VaD, diseases in which concomitant AD pathology is common.
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| 8. |
- Skillbäck, Tobias, et al.
(författare)
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Cerebrospinal fluid biomarkers for Alzheimer disease and subcortical axonal damage in 5,542 clinical samples.
- 2013
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Ingår i: Alzheimer's research & therapy. - : Springer Science and Business Media LLC. - 1758-9193. ; 5:5
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Tidskriftsartikel (refereegranskat)abstract
- The neuronal loss in Alzheimer disease (AD) has been described to affect grey matter in the cerebral cortex. However, in the elderly, AD pathology is likely to occur together with subcortical axonal degeneration on the basis of cerebrovascular disease. Therefore, we hypothesized that biomarkers for AD and subcortical axonal degeneration would correlate in patients undergoing testing for dementia biomarkers, particularly in older age groups.
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| 9. |
- Skillbäck, Tobias, et al.
(författare)
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Cerebrospinal fluid neurofilament light concentration in motor neuron disease and frontotemporal dementia predicts survival
- 2017
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Ingår i: Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration. - : Informa UK Limited. - 2167-8421 .- 2167-9223. ; 18:5-6, s. 397-403
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To aid diagnostics, patient stratification and studies seeking to find treatments for the related diseases motor neuron disease (MND) and frontotemporal dementia (FTD), there is a need to establish a way to assess disease severity and the amount of ongoing neurodegeneration. Previous studies have suggested that cerebrospinal fluid (CSF) neurofilament light (NFL) may serve this purpose. Methods: We cross-referenced the Swedish mortality registry with the laboratory database at Sahlgrenska University Hospital to produce a dataset of CSF NFL concentrations and mortality information for 715 MND patients, 87 FTD patients, and 107 healthy controls. Biomarker concentrations were analysed in relation to recorded cause of death and time of death. Results: MND patients had significantly higher CSF NFL concentrations than FTD patients. Both groups had significantly higher concentrations than the healthy controls (mean 709% increase in MND and 307% increase in FTD). Higher concentrations of CSF NFL were associated with shorter survival in both MND and FTD. Conclusions: The results of this study strengthen the notion of CSF NFL as a useful tool for determining disease intensity in MND and FTD patients. Further studies in patient cohorts with clinically subtyped and genetically classified diagnoses are needed.
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| 10. |
- Skillbäck, Tobias, et al.
(författare)
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Cerebrospinal fluid tau and amyloid-β1-42 in patients with dementia.
- 2015
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Ingår i: Brain : a journal of neurology. - : Oxford University Press (OUP). - 1460-2156 .- 0006-8950. ; 138:Pt 9, s. 2716-31
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Tidskriftsartikel (refereegranskat)abstract
- Progressive cognitive decline in combination with a cerebrospinal fluid biomarker pattern of low levels of amyloid-β1-42 and high levels of total tau and phosphorylated tau is typical of Alzheimer's disease. However, several neurodegenerative disorders may overlap with Alzheimer's disease both in regards to clinical symptoms and neuropathology. In a uniquely large cohort of dementia patients, we examined the associations of cerebrospinal fluid biomarkers for Alzheimer's disease molecular pathology with clinical dementia diagnoses and disease severity. We cross-referenced the Swedish Dementia Registry with the clinical laboratory database at the Sahlgrenska University Hospital. The final data set consisted of 5676 unique subjects with a clinical dementia diagnosis and a complete set of measurements for cerebrospinal fluid amyloid-β1-42, total tau and phosphorylated tau. In cluster analysis, disregarding clinical diagnosis, the optimal natural separation of this data set was into two clusters, with the majority of patients with early onset Alzheimer's disease (75%) and late onset Alzheimer's disease (73%) assigned to one cluster and the patients with vascular dementia (91%), frontotemporal dementia (94%), Parkinson's disease dementia (94%) and dementia with Lewy bodies (87%) to the other cluster. Frontotemporal dementia had the highest cerebrospinal fluid levels of amyloid-β1-42 and the lowest levels of total tau and phosphorylated tau. The highest levels of total tau and phosphorylated tau and the lowest levels of amyloid-β1-42 and amyloid-β1-42:phosphorylated tau ratios were found in Alzheimer's disease. Low amyloid-β1-42, high total tau and high phosphorylated tau correlated with low Mini-Mental State Examination scores in Alzheimer's disease. In Parkinson's disease dementia and vascular dementia low cerebrospinal fluid amyloid-β1-42 was associated with low Mini-Mental State Examination score. In the vascular dementia, frontotemporal dementia, dementia with Lewy bodies and Parkinson's disease dementia groups 53%, 34%, 67% and 53% of the subjects, respectively had abnormal amyloid-β1-42 levels, 41%, 41%, 28% and 28% had abnormal total tau levels, and 29%, 28%, 25% and 19% had abnormal phosphorylated tau levels. Cerebrospinal fluid biomarkers were strongly associated with specific clinical dementia diagnoses with Alzheimer's disease and frontotemporal dementia showing the greatest difference in biomarker levels. In addition, cerebrospinal fluid amyloid-β1-42, total tau, phosphorylated tau and the amyloid-β1-42:phosphorylated tau ratio all correlated with poor cognitive performance in Alzheimer's disease, as did cerebrospinal fluid amyloid-β1-42 in Parkinson's disease dementia and vascular dementia. The results support the use of cerebrospinal fluid biomarkers to differentiate between dementias in clinical practice, and to estimate disease severity.
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