| 1. |
- Bjerke, Maria, 1977, et al.
(författare)
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Confounding factors influencing amyloid Beta concentration in cerebrospinal fluid.
- 2010
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Ingår i: International journal of Alzheimer's disease. - : Hindawi Limited. - 2090-0252. ; 2010
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Tidskriftsartikel (refereegranskat)abstract
- Background. Patients afflicted with Alzheimer's disease (AD) exhibit a decrease in the cerebrospinal fluid (CSF) concentration of the 42 amino acid form of beta-amyloid (Abeta(42)). However, a high discrepancy between different centers in measured Abeta(42) levels reduces the utility of this biomarker as a diagnostic tool and in monitoring the effect of disease modifying drugs. Preanalytical and analytical confounding factors were examined with respect to their effect on the measured Abeta(42) level. Methods. Aliquots of CSF samples were either treated differently prior to Abeta(42) measurement or analyzed using different commercially available xMAP or ELISA assays. Results. Confounding factors affecting CSF Abeta(42) levels were storage in different types of test tubes, dilution with detergent-containing buffer, plasma contamination, heat treatment, and the origin of the immunoassays used for quantification. Conclusion. In order to conduct multicenter studies, a standardized protocol to minimize preanalytical and analytical confounding factors is warranted.
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| 2. |
- Brunnström, Hans, et al.
(författare)
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Cerebrospinal fluid biomarker results in relation to neuropathological dementia diagnoses.
- 2010
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Ingår i: Alzheimer's & dementia. - : Wiley. - 1552-5279 .- 1552-5260. ; 6:2, s. 104-109
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Clinical dementia diagnoses are not always consistent with neuropathological findings. As correct diagnosis is important for treatment and care, new diagnostic possibilities for dementia are in demand. Cerebrospinal fluid biomarkers should ideally be able to identify ongoing processes in the brain, but need to be further compared with neuropathological findings for evaluation of their diagnostic validity. METHODS: This study included 43 patients with a clinical dementia disorder. All patients were neuropathologically examined at the University Hospital in Lund, Sweden, during the years 2001-2008, and all had a lumbar puncture carried out as part of the clinical investigation during the time of cognitive impairment. RESULTS: Of eight patients, five with Alzheimer's disease had elevated total tau protein (T-tau) and decreased amyloid beta 1-42 protein (Abeta42), while both values for the other three patients were normal. Slightly elevated T-tau and/or decreased Abeta42 were also seen in several patients with other dementia diagnoses such as Lewy body disease, frontotemporal lobar degeneration and vascular dementia. Furthermore, T-tau levels did not differ markedly between patients with morphologically tau-positive and tau-negative frontotemporal lobar degeneration. Also, seven of nine patients with Creutzfeldt-Jacob disease exhibited pronounced elevation in T-tau concentration. CONCLUSION: From this rather limited study, being the first of its kind in Sweden, we may conclude that there is no perfect concordance between cerebrospinal fluid biomarker levels and pathological findings, which should be taken into account in the clinical diagnostic setting.
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| 3. |
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| 4. |
- Daborg, Jonny, et al.
(författare)
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Association of the RAGE G82S polymorphism with Alzheimer's disease
- 2010
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Ingår i: Journal of Neural Transmission. - : Springer Science and Business Media LLC. - 0300-9564 .- 1435-1463. ; 117:7, s. 861-867
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Tidskriftsartikel (refereegranskat)abstract
- The receptor for advanced glycation end-products (RAGE) has been implicated in several pathophysiological processes relevant to Alzheimer's disease (AD), including transport and synaptotoxicity of AD-associated amyloid beta (A beta) peptides. A recent Chinese study (Li et al. in J Neural Transm 117:97-104, 2010) suggested an association between the 82S allele of the functional single nucleotide polymorphism (SNP) G82S (rs2070600) in the RAGE-encoding gene AGER and risk of AD. The present study aimed to investigate associations between AGER, AD diagnosis, cognitive scores and cerebrospinal fluid AD biomarkers in a European cohort of 316 neurochemically verified AD cases and 579 controls. Aside from G82S, three additional tag SNPs were analyzed to cover the common genetic variation in AGER. The 82S allele was associated with increased risk of AD (P (c) = 0.04, OR = 2.0, 95% CI 1.2-3.4). There was no genetic interaction between AGER 82S and APOE epsilon 4 in producing increased risk of AD (P = 0.4), and none of the AGER SNPs showed association with A beta(42), T-tau, P-tau(181) or mini-mental state examination scores. The data speak for a weak, but significant effect of AGER on risk of AD.
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| 5. |
- De Meyer, Geert, et al.
(författare)
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Diagnosis-independent Alzheimer disease biomarker signature in cognitively normal elderly people.
- 2010
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Ingår i: Archives of neurology. - : American Medical Association (AMA). - 1538-3687 .- 0003-9942. ; 67:8, s. 949-56
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To identify biomarker patterns typical for Alzheimer disease (AD) in an independent, unsupervised way, without using information on the clinical diagnosis. DESIGN: Mixture modeling approach. SETTING: Alzheimer's Disease Neuroimaging Initiative database. Patients or Other PARTICIPANTS: Cognitively normal persons, patients with AD, and individuals with mild cognitive impairment. MAIN OUTCOME MEASURES: Cerebrospinal fluid-derived beta-amyloid protein 1-42, total tau protein, and phosphorylated tau(181P) protein concentrations were used as biomarkers on a clinically well-characterized data set. The outcome of the qualification analysis was validated on 2 additional data sets, 1 of which was autopsy confirmed. RESULTS: Using the US Alzheimer's Disease Neuroimaging Initiative data set, a cerebrospinal fluid beta-amyloid protein 1-42/phosphorylated tau(181P) biomarker mixture model identified 1 feature linked to AD, while the other matched the "healthy" status. The AD signature was found in 90%, 72%, and 36% of patients in the AD, mild cognitive impairment, and cognitively normal groups, respectively. The cognitively normal group with the AD signature was enriched in apolipoprotein E epsilon4 allele carriers. Results were validated on 2 other data sets. In 1 study consisting of 68 autopsy-confirmed AD cases, 64 of 68 patients (94% sensitivity) were correctly classified with the AD feature. In another data set with patients (n = 57) with mild cognitive impairment followed up for 5 years, the model showed a sensitivity of 100% in patients progressing to AD. CONCLUSIONS: The mixture modeling approach, totally independent of clinical AD diagnosis, correctly classified patients with AD. The unexpected presence of the AD signature in more than one-third of cognitively normal subjects suggests that AD pathology is active and detectable earlier than has heretofore been envisioned.
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| 6. |
- Gao, Carol Man, et al.
(författare)
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Aβ40 oligomers identified as a potential biomarker for the diagnosis of Alzheimer's disease.
- 2010
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Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 5:12
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimer's Disease (AD) is the most prevalent form of dementia worldwide, yet the development of therapeutics has been hampered by the absence of suitable biomarkers to diagnose the disease in its early stages prior to the formation of amyloid plaques and the occurrence of irreversible neuronal damage. Since oligomeric Aβ species have been implicated in the pathophysiology of AD, we reasoned that they may correlate with the onset of disease. As such, we have developed a novel misfolded protein assay for the detection of soluble oligomers composed of Aβ x-40 and x-42 peptide (hereafter Aβ40 and Aβ42) from cerebrospinal fluid (CSF). Preliminary validation of this assay with 36 clinical samples demonstrated the presence of aggregated Aβ40 in the CSF of AD patients. Together with measurements of total Aβ42, diagnostic sensitivity and specificity greater than 95% and 90%, respectively, were achieved. Although larger sample populations will be needed to confirm this diagnostic sensitivity, our studies demonstrate a sensitive method of detecting circulating Aβ40 oligomers from AD CSF and suggest that these oligomers could be a powerful new biomarker for the early detection of AD.
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| 7. |
- Hansson, Oskar, et al.
(författare)
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Evaluation of plasma Abeta(40) and Abeta(42) as predictors of conversion to Alzheimer's disease in patients with mild cognitive impairment.
- 2010
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Ingår i: Neurobiology of aging. - : Elsevier BV. - 1558-1497 .- 0197-4580. ; 31:3, s. 357-67
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Tidskriftsartikel (refereegranskat)abstract
- Numerous studies have shown a marked decrease of beta-amyloid(42) (Abeta(42)) in the cerebrospinal fluid (CSF) of patients with incipient Alzheimer's disease (AD). However, studies on Abeta in plasma are contradictory, and show very marginal differences between patients and controls. Here, we analyzed plasma samples using a new multiplex immunoassay for simultaneous analysis of Abeta(1-40), Abeta(n-40), Abeta(1-42), and Abeta(n-42). The plasma samples were obtained at baseline from two independent cohorts of patients with mild cognitive impairment (MCI) and age-matched controls. In the first cohort, 41% of the 117 MCI cases converted to AD during a clinical follow-up period of 4-7 years. In the second cohort, 14% of the 110 MCI subjects developed AD during a clinical follow-up period of 2-4 years. None of the plasma Abeta isoforms differed between MCI patients that subsequently developed AD and healthy controls or stable MCI patients. The Cox proportional hazards model did not reveal any differences in the probability of progression from MCI to AD related to plasma Abeta levels. In contrast, low levels of Abeta(1-42) in CSF were strongly associated with increased risk of future AD. The absence of a change in plasma Abeta in incipient AD, despite the marked change in CSF, may be explained by the lack of a correlation between the levels of Abeta(1-42) in CSF and plasma. In conclusion, the results show that CSF biomarkers are better predictors of progression to AD than plasma Abeta isoforms.
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| 8. |
- Hertze, Joakim, et al.
(författare)
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Evaluation of CSF Biomarkers as Predictors of Alzheimer's Disease: A Clinical Follow-Up Study of 4.7 Years.
- 2010
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Ingår i: Journal of Alzheimer's disease : JAD. - 1875-8908. ; 21, s. 1119-1128
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we determined the diagnostic accuracy of cerebrospinal fluid (CSF) biomarkers to predict development of Alzheimer's disease (AD) within five years in patients with mild cognitive impairment (MCI). To do so, the levels of tau, phosphorylated tau, Abeta42, Abeta40, Abeta38, sAbetaPPalpha, and sAbetaPPbeta were analyzed in 327 CSF samples obtained at baseline from patients with AD (n= 94), MCI (n= 166), depressive disorder (n= 29), and cognitively healthy controls (n= 38). In the cohort with MCI at baseline, 33% subsequently developed AD and 16% developed other types of dementia; however, 51% were still cognitively stable after a follow-up of 4.7 years (range 3.0-7.4). Optimal cut-offs for each biomarker or combinations of biomarkers were defined in the AD, control, and depressive disorder groups. Several combinations resulted in sensitivity and specificity levels > 85% for differentiation of AD from controls and depressive disorder. Using the previously established cut-offs, a combination of Abeta42 and tau could predict future development of AD in MCI patients with a sensitivity of 88%, specificity 82%, positive predictive value 71%, and negative predictive value 94%. MCI patients with both low Abeta42 and high tau levels had a substantially increased risk of developing AD (OR 20; 95% CI 6-58), even after adjustment for confounding factors. Ultimately, CSF biomarkers can stratify MCI patients into those with very low or high risk for future development of AD. However, the specificities and positive predictive values are still too low to be able to diagnose AD before the patients fulfill the clinical criteria.
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| 9. |
- Landgren, Sara, 1980, et al.
(författare)
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No Association of VEGF Polymorphims with Alzheimer's Disease
- 2010
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Ingår i: NeuroMolecular Medicine. - : Springer Science and Business Media LLC. - 1535-1084 .- 1559-1174. ; 12:3, s. 224-228
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Tidskriftsartikel (refereegranskat)abstract
- The vascular hypothesis of Alzheimer's disease (AD) has brought the vascular endothelial growth factor (VEGF) into focus. The genomic region including the VEGF gene has been linked to AD and single nucleotide polymorphisms (SNPs) of the VEGF have in previous studies been associated with AD risk. To further evaluate these findings, we genotyped two SNPs in the VEGF gene (rs699947 [-2578]) and rs1570360 [-1154]) by TaqMan Allelic Discrimination in a study sample including AD patients (n = 801) and controls (n = 286). In a subgroup of the population these SNPs were analyzed in relation to APOE epsilon 4 genotype, to cerebrospinal fluid biomarkers (T-tau, P-tau, and beta(42)-Amyloid) as well as to neuropathological markers for AD (neurofibrillary tangles and senile plaques). No significant associations with risk for AD or any of the studied biomarkers could be found in this study, thus not supporting VEGF as being a major risk gene for AD.
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| 10. |
- Sjölander, Annica, 1969, et al.
(författare)
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BACE1 gene variants do not influence BACE1 activity, levels of APP or Abeta isoforms in CSF in Alzheimer's disease.
- 2010
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Ingår i: Molecular neurodegeneration. - : Springer Science and Business Media LLC. - 1750-1326. ; 5:1
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Tidskriftsartikel (refereegranskat)abstract
- ABSTRACT: The BACE1 gene encodes the beta-site APP-cleaving enzyme 1 and has been associated with Alzheimer's disease (AD). BACE1 is the most important beta-secretase responsible for the generation of Alzheimer-associated amyloid beta-proteins (Abeta) and may play a role in the amyloidogenic process in AD. We hypothesized that BACE1 gene variants might influence BACE1 activity or other markers for APP metabolism in the cerebrospinal fluid (CSF) and thereby contribute to the development of AD. We genotyped a Swedish sample of 269 AD patients for the rs638405 single nucleotide polymorphism (SNP) in the BACE1 gene and correlated genotype data to a broad range of amyloid-related biomarkers in CSF, including BACE1 activity, levels of Abeta40, Abeta42, alpha- and beta-cleaved soluble APP (alpha-sAPP and beta-sAPP), as well as markers for Alzheimer-type axonal degeneration, i.e., total-tau and phospho-tau181. Gene variants of BACE1 were neither associated with amyloid-related biomarkers, nor with markers for axonal degeneration in AD.
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