Dataset Information

Nonlinear Association Between Cerebrospinal Fluid and Florbetapir F-18 ?-Amyloid Measures Across the Spectrum of Alzheimer Disease.

ABSTRACT: Cerebrospinal fluid (CSF) and positron emission tomographic (PET) amyloid biomarkers have been proposed for the detection of Alzheimer disease (AD) pathology in living patients and for the tracking of longitudinal changes, but the relation between biomarkers needs further study.To determine the association between CSF and PET amyloid biomarkers (cross-sectional and longitudinal measures) and compare the cutoffs for these measures.Longitudinal clinical cohort study from 2005 to 2014 including 820 participants with at least 1 florbetapir F-18 (hereafter referred to as simply florbetapir)-PET scan and at least 1 CSF ?-amyloid 1-42 (A?1-42) sample obtained within 30 days of each other (501 participants had a second PET scan after 2 years, including 150 participants with CSF A?1-42 measurements). Data were obtained from the Alzheimer's Disease Neuroimaging Initiative database.Four different PET scans processing pipelines from 2 different laboratories were compared. The PET cutoff values were established using a mixture-modeling approach, and different mathematical models were applied to define the association between CSF and PET amyloid measures.The values of the CSF A?1-42 samples and florbetapir-PET scans showed a nonlinear association (R2 = 0.48-0.66), with the strongest association for values in the middle range. The presence of a larger dynamic range of florbetapir-PET scan values in the higher range compared with the CSF A?1-42 plateau explained the differences in correlation with cognition (R2 = 0.36 and R2 = 0.25, respectively). The APOE genotype significantly modified the association between both biomarkers. The PET cutoff values derived from an unsupervised classifier converged with previous PET cutoff values and the established CSF A?1-42 cutoff levels. There was no association between longitudinal A?1-42 levels and standardized uptake value ratios during follow-up.The association between both biomarkers is limited to a middle range of values, is modified by the APOE genotype, and is absent for longitudinal changes; 4 different approaches in 2 different platforms converge on similar pathological A? cutoff levels; and different pipelines to process PET scans showed correlated but not identical results. Our findings suggest that both biomarkers measure different aspects of AD A? pathology.

SUBMITTER: Toledo JB

PROVIDER: S-EPMC5642905 | biostudies-literature | 2015 May

REPOSITORIES: biostudies-literature

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Nonlinear Association Between Cerebrospinal Fluid and Florbetapir F-18 β-Amyloid Measures Across the Spectrum of Alzheimer Disease.

Toledo Jon B JB Bjerke Maria M Da Xiao X Landau Susan M SM Foster Norman L NL Jagust William W Jack Clifford C Weiner Michael M Davatzikos Christos C Shaw Leslie M LM Trojanowski John Q JQ

JAMA neurology 20150501 5

<h4>Importance</h4>Cerebrospinal fluid (CSF) and positron emission tomographic (PET) amyloid biomarkers have been proposed for the detection of Alzheimer disease (AD) pathology in living patients and for the tracking of longitudinal changes, but the relation between biomarkers needs further study.<h4>Objective</h4>To determine the association between CSF and PET amyloid biomarkers (cross-sectional and longitudinal measures) and compare the cutoffs for these measures.<h4>Design, setting, and part ...[more]

PMID: 25822737

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Project description:An (18)F-labeled PET amyloid-beta (Abeta) imaging agent could facilitate the clinical evaluation of late-life cognitive impairment by providing an objective measure for Alzheimer disease (AD) pathology. Here we present the results of a clinical trial with (E)-4-(2-(6-(2-(2-(2-(18)F-fluoroethoxy)ethoxy)ethoxy)pyridin-3-yl)vinyl)-N-methyl benzenamine ((18)F-AV-45 or florbetapir [corrected] F 18).An open-label, multicenter brain imaging, metabolism, and safety study of (18)F-AV-45 was performed on 16 patients with AD (Mini-Mental State Examination score, 19.3 +/- 3.1; mean age +/- SD, 75.8 +/- 9.2 y) and 16 cognitively healthy controls (HCs) (Mini-Mental State Examination score, 29.8 +/- 0.45; mean age +/- SD, 72.5 +/- 11.6 y). Dynamic PET was performed over a period of approximately 90 min after injection of the tracer (370 MBq [10 mCi]). Standardized uptake values and cortical-to-cerebellum standardized uptake value ratios (SUVRs) were calculated. A simplified reference tissue method was used to generate distribution volume ratio (DVR) parametric maps for a subset of subjects.Valid PET data were available for 11 AD patients and 15 HCs. (18)F-AV-45 accumulated in cortical regions expected to be high in Abeta deposition (e.g., precuneus and frontal and temporal cortices) in AD patients; minimal accumulation of the tracer was seen in cortical regions of HCs. The cortical-to-cerebellar SUVRs in AD patients showed continual substantial increases through 30 min after administration, reaching a plateau within 50 min. The 10-min period from 50 to 60 min after administration was taken as a representative sample for further analysis. The cortical average SUVR for this period was 1.67 +/- 0.175 for patients with AD versus 1.25 +/- 0.177 for HCs. Spatially normalized DVRs generated from PET dynamic scans were highly correlated with SUVR (r = 0.58-0.88, P < 0.005) and were significantly greater for AD patients than for HCs in cortical regions but not in subcortical white matter or cerebellar regions. No clinically significant changes in vital signs, electrocardiogram, or laboratory values were observed.(18)F-AV-45 was well tolerated, and PET showed significant discrimination between AD patients and HCs, using either a parametric reference region method (DVR) or a simplified SUVR calculated from 10 min of scanning 50-60 min after (18)F-AV-45 administration.

Project description:Sphingolipids are important in many brain functions but their role in Alzheimer's disease (AD) is not completely defined. A major limit is availability of fresh brain tissue with defined AD pathology. The discovery that cerebrospinal fluid (CSF) contains abundant nanoparticles that include synaptic vesicles and large dense core vesicles offer an accessible sample to study these organelles, while the supernatant fluid allows study of brain interstitial metabolism. Our objective was to characterize sphingolipids in nanoparticles representative of membrane vesicle metabolism, and in supernatant fluid representative of interstitial metabolism from study participants with varying levels of cognitive dysfunction. We recently described the recruitment, diagnosis, and CSF collection from cognitively normal or impaired study participants. Using liquid chromatography tandem mass spectrometry, we report that cognitively normal participants had measureable levels of sphingomyelin, ceramide, and dihydroceramide species, but that their distribution differed between nanoparticles and supernatant fluid, and further differed in those with cognitive impairment. In CSF from AD compared with cognitively normal participants: a) total sphingomyelin levels were lower in nanoparticles and supernatant fluid; b) levels of ceramide species were lower in nanoparticles and higher in supernatant fluid; c) three sphingomyelin species were reduced in the nanoparticle fraction. Moreover, three sphingomyelin species in the nanoparticle fraction were lower in mild cognitive impairment compared with cognitively normal participants. The activity of acid, but not neutral sphingomyelinase was significantly reduced in the CSF from AD participants. The reduction in acid sphingomylinase in CSF from AD participants was independent of depression and psychotropic medications. Acid sphingomyelinase activity positively correlated with amyloid ?42 concentration in CSF from cognitively normal but not impaired participants. In dementia, altered sphingolipid metabolism, decreased acid sphingomyelinase activity and its lost association with CSF amyloid ?42 concentration, underscores the potential of sphingolipids as disease biomarkers, and acid sphingomyelinase as a target for AD diagnosis and/or treatment.

Project description:ImportanceIncreasing evidence suggests an important role of liver function in the pathophysiology of Alzheimer disease (AD). The liver is a major metabolic hub; therefore, investigating the association of liver function with AD, cognition, neuroimaging, and CSF biomarkers would improve the understanding of the role of metabolic dysfunction in AD.ObjectiveTo examine whether liver function markers are associated with cognitive dysfunction and the "A/T/N" (amyloid, tau, and neurodegeneration) biomarkers for AD.Design, setting, and participantsIn this cohort study, serum-based liver function markers were measured from September 1, 2005, to August 31, 2013, in 1581 AD Neuroimaging Initiative participants along with cognitive measures, cerebrospinal fluid (CSF) biomarkers, brain atrophy, brain glucose metabolism, and amyloid-β accumulation. Associations of liver function markers with AD-associated clinical and A/T/N biomarkers were assessed using generalized linear models adjusted for confounding variables and multiple comparisons. Statistical analysis was performed from November 1, 2017, to February 28, 2019.ExposuresFive serum-based liver function markers (total bilirubin, albumin, alkaline phosphatase, alanine aminotransferase, and aspartate aminotransferase) from AD Neuroimaging Initiative participants were used as exposure variables.Main outcomes and measuresPrimary outcomes included diagnosis of AD, composite scores for executive functioning and memory, CSF biomarkers, atrophy measured by magnetic resonance imaging, brain glucose metabolism measured by fludeoxyglucose F 18 (18F) positron emission tomography, and amyloid-β accumulation measured by [18F]florbetapir positron emission tomography.ResultsParticipants in the AD Neuroimaging Initiative (n = 1581; 697 women and 884 men; mean [SD] age, 73.4 [7.2] years) included 407 cognitively normal older adults, 20 with significant memory concern, 298 with early mild cognitive impairment, 544 with late mild cognitive impairment, and 312 with AD. An elevated aspartate aminotransferase (AST) to alanine aminotransferase (ALT) ratio and lower levels of ALT were associated with AD diagnosis (AST to ALT ratio: odds ratio, 7.932 [95% CI, 1.673-37.617]; P = .03; ALT: odds ratio, 0.133 [95% CI, 0.042-0.422]; P = .004) and poor cognitive performance (AST to ALT ratio: β [SE], -0.465 [0.180]; P = .02 for memory composite score; β [SE], -0.679 [0.215]; P = .006 for executive function composite score; ALT: β [SE], 0.397 [0.128]; P = .006 for memory composite score; β [SE], 0.637 [0.152]; P < .001 for executive function composite score). Increased AST to ALT ratio values were associated with lower CSF amyloid-β 1-42 levels (β [SE], -0.170 [0.061]; P = .04) and increased amyloid-β deposition (amyloid biomarkers), higher CSF phosphorylated tau181 (β [SE], 0.175 [0.055]; P = .02) (tau biomarkers) and higher CSF total tau levels (β [SE], 0.160 [0.049]; P = .02) and reduced brain glucose metabolism (β [SE], -0.123 [0.042]; P = .03) (neurodegeneration biomarkers). Lower levels of ALT were associated with increased amyloid-β deposition (amyloid biomarkers), and reduced brain glucose metabolism (β [SE], 0.096 [0.030]; P = .02) and greater atrophy (neurodegeneration biomarkers).Conclusions and relevanceConsistent associations of serum-based liver function markers with cognitive performance and A/T/N biomarkers for AD highlight the involvement of metabolic disturbances in the pathophysiology of AD. Further studies are needed to determine if these associations represent a causative or secondary role. Liver enzyme involvement in AD opens avenues for novel diagnostics and therapeutics.

Dataset Information

Nonlinear Association Between Cerebrospinal Fluid and Florbetapir F-18 ?-Amyloid Measures Across the Spectrum of Alzheimer Disease.

Publications

Nonlinear Association Between Cerebrospinal Fluid and Florbetapir F-18 β-Amyloid Measures Across the Spectrum of Alzheimer Disease.

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