| 1. |
- Deming, Y., et al.
(författare)
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Neuropathology-based APOE genetic risk score better quantifies Alzheimer's risk
- 2023
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Ingår i: Alzheimers & Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 19:8, s. 3406-3416
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Tidskriftsartikel (refereegranskat)abstract
- IntroductionApolipoprotein E (APOE) epsilon 4-carrier status or epsilon 4 allele count are included in analyses to account for the APOE genetic effect on Alzheimer's disease (AD); however, this does not account for protective effects of APOE epsilon 2 or heterogeneous effect of epsilon 2, epsilon 3, and epsilon 4 haplotypes. MethodsWe leveraged results from an autopsy-confirmed AD study to generate a weighted risk score for APOE (APOE-npscore). We regressed cerebrospinal fluid (CSF) amyloid and tau biomarkers on APOE variables from the Wisconsin Registry for Alzheimer's Prevention (WRAP), Wisconsin Alzheimer's Disease Research Center (WADRC), and Alzheimer's Disease Neuroimaging Initiative (ADNI). ResultsThe APOE-npscore explained more variance and provided a better model fit for all three CSF measures than APOE epsilon 4-carrier status and epsilon 4 allele count. These findings were replicated in ADNI and observed in subsets of cognitively unimpaired (CU) participants. DiscussionThe APOE-npscore reflects the genetic effect on neuropathology and provides an improved method to account for APOE in AD-related analyses.
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| 2. |
- Ennis, G. E., et al.
(författare)
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Insulin resistance is related to cognitive decline but not change in CSF biomarkers of Alzheimer's disease in non-demented adults
- 2021
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Ingår i: Alzheimer's & Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Introduction We investigated whether insulin resistance (IR) was associated with longitudinal age-related change in cognition and biomarkers of Alzheimer's disease (AD) pathology and neurodegeneration in middle-aged and older adults who were non-demented at baseline. Methods IR was measured with homeostatic model assessment of insulin resistance (HOMA2-IR). Core AD-related cerebrospinal fluid (CSF) biomarkers and cognition were assessed, respectively, on n = 212 (1 to 5 visits) and n = 1299 (1 to 6 visits). Linear mixed models tested whether HOMA2-IR moderated age-related change in CSF biomarkers and cognition. Linear regressions tested whether HOMA2-IR x apolipoprotein E epsilon 4 allele (APOE epsilon 4) carrier status predicted amyloid beta [A beta] chronicity (estimated duration of amyloid positron emission tomography [PET] positivity) (n = 253). Results Higher HOMA2-IR was associated with greater cognitive decline but not with changes in CSF biomarkers. HOMA2-IR x APOE4 was not related to A beta chronicity but was significantly associated with CSF phosphorylated tau (P-tau)(181)/A beta(42) level. Discussion In non-demented adults IR may not be directly associated with age-related change in AD biomarkers. Additional research is needed to determine mechanisms linking IR to cognitive decline.
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| 3. |
- Hoscheidt, S. M., et al.
(författare)
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Insulin Resistance is Associated with Increased Levels of Cerebrospinal Fluid Biomarkers of Alzheimer's Disease and Reduced Memory Function in At-Risk Healthy Middle-Aged Adults
- 2016
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Ingår i: Journal of Alzheimers Disease. - 1387-2877. ; 52:4, s. 1373-1383
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Tidskriftsartikel (refereegranskat)abstract
- Background: Type 2 diabetes is associated with an increased risk for Alzheimer's disease (AD). Regulation of normal insulin function may be important in reducing the prevalence of dementia due to AD, particularly in individuals who harbor genetic risk for or have a parental family history of AD. The relationship between insulin resistance (IR) and AD pathology remains poorly understood, particularly in midlife prior to the onset of clinical metabolic disease or cognitive decline. Objective: We examined associations between IR as indexed by HOMA-IR, cerebrospinal fluid (CSF) biomarkers of AD pathology, and memory in middle-aged adults enriched for AD. We postulated that higher HOMA-IR and APOE epsilon 4 carriage would be associated with greater CSF AD pathology and poor memory performance. Methods: Cognitively asymptomatic middle-aged adults (N = 70, mean age = 57.7 years) from the Wisconsin Alzheimer's Disease Research Center with a parental family history of dementia due to AD underwent lumbar puncture, blood draw, and neuropsychological testing. CSF AD biomarkers including soluble amyloid-beta protein precursor beta (sA beta PP beta), amyloid-beta 42 (A beta(42)), and phosphorylated tau (P-tau(181)) were examined with respect to HOMA-IR and APOE epsilon 4 status. Delayed memory performance was examined with respect to HOMA-IR, CSF AD biomarkers, and APOE epsilon 4 status. Results: Higher HOMA-IR was associated with higher sA beta PP beta and A beta(42). APOE epsilon 4 carriers had significantly higher levels of sA beta PP beta, sA beta PP beta, and P-tau(181)/A beta(42) compared to noncarriers. The concurrent presence of higher HOMA-IR and CSF AD pathology predicted worse delayed memory performance. Conclusion: Overall, the findings suggest that IR and APOE epsilon 4 are contributing factors to the development of AD pathology in midlife, and provide support for targeting insulin function as a potentially modifiable risk factor for AD.
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| 4. |
- Jonaitis, E. M., et al.
(författare)
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Crosswalk study on blood collection-tube types for Alzheimer's disease biomarkers
- 2022
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Ingår i: Alzheimer's & Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Introduction Blood-based Alzheimer's disease (AD) biomarkers show promise, but pre-analytical protocol differences may pose problems. We examined seven AD blood biomarkers (amyloid beta [A beta]42${\rm{A\beta }}]{_{42}}$, A beta 40${\rm{A}}{{{\beta}}_{40}}$, phosphorylatedtau[p-tau181${\rm{phosphorylated\;tau\;[p - ta}}{{\rm{u}}_{181}}$, total tau [t-tau], neurofilament light chain [NfL], A beta 4240,${\rm{A}}{{{\beta}}_{\frac{{42}}{{40}}}},$ and p-tau181A beta 42$\frac{{{\rm{p - ta}}{{\rm{u}}_{181}}}}{{{\rm{A}}{{{\beta}}_{42}}}}$) in three collection tube types (ethylenediaminetetraacetic acid [EDTA] plasma, heparin plasma, serum). Methods Plasma and serum were obtained from cerebrospinal fluid or amyloid positron emission tomography-positive and -negative participants (N = 38) in the Wisconsin Registry for Alzheimer's Prevention. We modeled AD biomarker values observed in EDTA plasma versus heparin plasma and serum, and assessed correspondence with brain amyloidosis. Results Results suggested bias due to tube type, but crosswalks are possible for some analytes, with excellent model fit for NfL (R2${{\rm{R}}<^>2}\;$= 0.94), adequate for amyloid (R2${{\rm{R}}<^>2}\;$= 0.40-0.69), and weaker for t-tau (R2${{\rm{R}}<^>2}\;$= 0.04-0.42) and p-tau181${\rm{p - ta}}{{\rm{u}}_{181}}$ ( R2${{\rm{R}}<^>2}\;$= 0.22-0.29). Brain amyloidosis differentiated several measures, especially EDTA plasma pTau181A beta 42$\frac{{{\rm{pTa}}{{\rm{u}}_{181}}}}{{{\rm{A}}{\beta _{42}}}}$ (d$d\;$= 1.29). Discussion AD biomarker concentrations vary by tube type. However, correlations for some biomarkers support harmonization across types, suggesting cautious optimism for use in banked blood.
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| 5. |
- Ma, Y., et al.
(författare)
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Measurement batch differences and between-batch conversion of Alzheimer's disease cerebrospinal fluid biomarker values
- 2021
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Ingår i: Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring. - : Wiley. - 2352-8729. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Introduction Batch differences in cerebrospinal fluid (CSF) biomarker measurement can introduce bias into analyses for Alzheimer's disease studies. We evaluated and adjusted for batch differences using statistical methods. Methods A total of 792 CSF samples from 528 participants were assayed in three batches for 12 biomarkers and 3 biomarker ratios. Batch differences were assessed using Bland-Altman plot, paired t test, Pitman-Morgan test, and linear regression. Generalized linear models were applied to convert CSF values between batches. Results We found statistically significant batch differences for all biomarkers and ratios, except that neurofilament light was comparable between batches 1 and 2. The conversion models generally had high R-2 except for converting P-tau between batches 1 and 3. Discussion Between-batch conversion allows harmonized CSF values to be used in the same analysis. Such method may be applied to adjust for other sources of variability in measuring CSF or other types of biomarkers.
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| 6. |
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| 7. |
- Morrow, A., et al.
(författare)
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Cerebrospinal Fluid Sphingomyelins in Alzheimer's Disease, Neurodegeneration, and Neuroinflammation
- 2022
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Ingår i: Journal of Alzheimers Disease. - : IOS Press. - 1387-2877 .- 1875-8908. ; 90:2, s. 667-680
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Tidskriftsartikel (refereegranskat)abstract
- Background: Sphingomyelin (SM) levels have been associated with Alzheimer's disease (AD), but the association direction has been inconsistent and research on cerebrospinal fluid (CSF) SMs has been limited by sample size, breadth of SMs examined, and diversity of biomarkers available. Objective: Here, we seek to build on our understanding of the role of SM metabolites in AD by studying a broad range of CSF SMs and biomarkers of AD, neurodegeneration, and neuroinflammation. Methods: Leveraging two longitudinal AD cohorts with metabolome-wide CSF metabolomics data (n = 502), we analyzed the relationship between the levels of 12 CSF SMs, and AD diagnosis and biomarkers of pathology, neurodegeneration, and neuroinflammation using logistic, linear, and linear mixed effects models. Results: No SMs were significantly associated with AD diagnosis, mild cognitive impairment, or amyloid biomarkers. Phosphorylated tau, neurofilament light, alpha-synuclein, neurogranin, soluble triggering receptor expressed on myeloid cells 2, and chitinase-3-like-protein 1 were each significantly, positively associated with at least 5 of the SMs. Conclusion: The associations between SMs and biomarkers of neurodegeneration and neuroinflammation, but not biomarkers of amyloid or diagnosis of AD, point to SMs as potential biomarkers for neurodegeneration and neuroinflammation that may not be AD-specific.
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| 8. |
- Panyard, D. J., et al.
(författare)
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Large-scale proteome and metabolome analysis of CSF implicates altered glucose and carbon metabolism and succinylcarnitine in Alzheimer's disease
- 2023
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Ingår i: Alzheimers & Dementia. - 1552-5260.
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTIONA hallmark of Alzheimer's disease (AD) is the aggregation of proteins (amyloid beta [A] and hyperphosphorylated tau [T]) in the brain, making cerebrospinal fluid (CSF) proteins of particular interest. METHODSWe conducted a CSF proteome-wide analysis among participants of varying AT pathology (n = 137 participants; 915 proteins) with nine CSF biomarkers of neurodegeneration and neuroinflammation. RESULTSWe identified 61 proteins significantly associated with the AT category (P < 5.46 x 10(-5)) and 636 significant protein-biomarker associations (P < 6.07 x 10(-6)). Proteins from glucose and carbon metabolism pathways were enriched among amyloid- and tau-associated proteins, including malate dehydrogenase and aldolase A, whose associations with tau were replicated in an independent cohort (n = 717). CSF metabolomics identified and replicated an association of succinylcarnitine with phosphorylated tau and other biomarkers. DISCUSSIONThese results implicate glucose and carbon metabolic dysregulation and increased CSF succinylcarnitine levels with amyloid and tau pathology in AD. HIGHLIGHTSCerebrospinal fluid (CSF) proteome enriched for extracellular, neuronal, immune, and protein processing.Glucose/carbon metabolic pathways enriched among amyloid/tau-associated proteins.Key glucose/carbon metabolism protein associations independently replicated.CSF proteome outperformed other omics data in predicting amyloid/tau positivity.CSF metabolomics identified and replicated a succinylcarnitine-phosphorylated tau association.
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| 9. |
- Racine, Annie M, et al.
(författare)
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Biomarker clusters are differentially associated with longitudinal cognitive decline in late midlife.
- 2016
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Ingår i: Brain : a journal of neurology. - : Oxford University Press (OUP). - 1460-2156. ; 139:Pt 8, s. 2261-74
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Tidskriftsartikel (refereegranskat)abstract
- The ability to detect preclinical Alzheimer's disease is of great importance, as this stage of the Alzheimer's continuum is believed to provide a key window for intervention and prevention. As Alzheimer's disease is characterized by multiple pathological changes, a biomarker panel reflecting co-occurring pathology will likely be most useful for early detection. Towards this end, 175 late middle-aged participants (mean age 55.9 ± 5.7 years at first cognitive assessment, 70% female) were recruited from two longitudinally followed cohorts to undergo magnetic resonance imaging and lumbar puncture. Cluster analysis was used to group individuals based on biomarkers of amyloid pathology (cerebrospinal fluid amyloid-β42/amyloid-β40 assay levels), magnetic resonance imaging-derived measures of neurodegeneration/atrophy (cerebrospinal fluid-to-brain volume ratio, and hippocampal volume), neurofibrillary tangles (cerebrospinal fluid phosphorylated tau181 assay levels), and a brain-based marker of vascular risk (total white matter hyperintensity lesion volume). Four biomarker clusters emerged consistent with preclinical features of (i) Alzheimer's disease; (ii) mixed Alzheimer's disease and vascular aetiology; (iii) suspected non-Alzheimer's disease aetiology; and (iv) healthy ageing. Cognitive decline was then analysed between clusters using longitudinal assessments of episodic memory, semantic memory, executive function, and global cognitive function with linear mixed effects modelling. Cluster 1 exhibited a higher intercept and greater rates of decline on tests of episodic memory. Cluster 2 had a lower intercept on a test of semantic memory and both Cluster 2 and Cluster 3 had steeper rates of decline on a test of global cognition. Additional analyses on Cluster 3, which had the smallest hippocampal volume, suggest that its biomarker profile is more likely due to hippocampal vulnerability and not to detectable specific volume loss exceeding the rate of normal ageing. Our results demonstrate that pathology, as indicated by biomarkers, in a preclinical timeframe is related to patterns of longitudinal cognitive decline. Such biomarker patterns may be useful for identifying at-risk populations to recruit for clinical trials.
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| 10. |
- Starks, E. J., et al.
(författare)
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Insulin Resistance is Associated with Higher Cerebrospinal Fluid Tau Levels in Asymptomatic APOE epsilon 4 Carriers
- 2015
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Ingår i: Journal of Alzheimers Disease. - : IOS Press. - 1387-2877 .- 1875-8908. ; 46:2, s. 525-533
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Tidskriftsartikel (refereegranskat)abstract
- Background: Insulin resistance (IR) is linked with the occurrence of pathological features observed in Alzheimer's disease (AD), including neurofibrillary tangles and amyloid plaques. However, the extent to which IR is associated with AD pathology in the cognitively asymptomatic stages of preclinical AD remains unclear. Objective: To determine the extent to which IR is linked with amyloid and tau pathology in late-middle-age. Method: Cerebrospinal fluid (CSF) samples collected from 113 participants enrolled in the Wisconsin Registry for Alzheimer's Prevention study (mean age = 60.6 years), were assayed for AD-related markers of interest: A beta(42), P-Tau(181), and T-Tau. IR was determined using the Homeostatic Model Assessment for Insulin Resistance (HOMA-IR). Linear regression was used to test the effect of IR, and APOE epsilon 4, on tau and amyloid pathology. We hypothesized that greater IR would be associated with higher CSF P-Tau181 and T-Tau, and lower CSF A beta 42. Results: No significant main effects of HOMA-IR on P-Tau181, T-Tau, or A beta 42 were observed; however, significant interactions were observed between HOMA-IR and APOE epsilon 4 on CSF markers related to tau. Among APOE epsilon 4 carriers, higher HOMA-IR was associated with higher P-Tau181 and T-Tau. Among APOE epsilon 4 non-carriers, HOMA-IR was negatively associated with P-Tau181 and T-Tau. We found no effects of IR on A beta 42 levels in CSF. Conclusion: IR among asymptomatic APOE epsilon 4 carriers was associated with higher P-Tau(181) and T-Tau in late-middle age. The results suggest that IR may contribute to tau-related neurodegeneration in preclinical AD. The findings may have implications for developing prevention strategies aimed at modifying IR in mid-life.
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