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Gareau DS, RochaKim N, Choudhury A, Bamkole M, Snuderl M, Zou J, Yaroslavsky A, Jacques SL, Strickland S, Krueger JG, Ahn HJ. Fiberoptic hemodynamic spectroscopy reveals abnormal cerebrovascular reactivity in a freely moving mouse model of Alzheimer's disease. Front Mol Neurosci 2023; 16:1163447. [PMID: 37465366 PMCID: PMC10350529 DOI: 10.3389/fnmol.2023.1163447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 05/22/2023] [Indexed: 07/20/2023] Open
Abstract
Many Alzheimer's disease (AD) patients suffer from altered cerebral blood flow and damaged cerebral vasculature. Cerebrovascular dysfunction could play an important role in this disease. However, the mechanism underlying a vascular contribution in AD is still unclear. Cerebrovascular reactivity (CVR) is a critical mechanism that maintains cerebral blood flow and brain homeostasis. Most current methods to analyze CVR require anesthesia which is known to hamper the investigation of molecular mechanisms underlying CVR. We therefore combined spectroscopy, spectral analysis software, and an implantable device to measure cerebral blood volume fraction (CBVF) and oxygen saturation (SO2) in unanesthetized, freely-moving mice. Then, we analyzed basal CBVF and SO2, and CVR of 5-month-old C57BL/6 mice during hypercapnia as well as during basic behavior such as grooming, walking and running. Moreover, we analyzed the CVR of freely-moving AD mice and their wildtype (WT) littermates during hypercapnia and could find impaired CVR in AD mice compared to WT littermates. Our results suggest that this optomechanical approach to reproducibly getting light into the brain enabled us to successfully measure CVR in unanesthetized freely-moving mice and to find impaired CVR in a mouse model of AD.
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Affiliation(s)
- Daniel S. Gareau
- Laboratory of Investigative Dermatology, The Rockefeller University, New York, NY, United States
| | - Nicholas RochaKim
- Department of Pharmacology, Physiology and Neuroscience, Rutgers-New Jersey Medical School, Newark, NJ, United States
| | - Arnab Choudhury
- Department of Pharmacology, Physiology and Neuroscience, Rutgers-New Jersey Medical School, Newark, NJ, United States
| | - Michael Bamkole
- Department of Pharmacology, Physiology and Neuroscience, Rutgers-New Jersey Medical School, Newark, NJ, United States
| | - Matija Snuderl
- Department of Pathology, NYU Langone Health and Grossman School of Medicine, New York, NY, United States
| | - Julia Zou
- Laboratory of Investigative Dermatology, The Rockefeller University, New York, NY, United States
| | - Anna Yaroslavsky
- Department of Physics and Applied Physics, University of Massachusetts, Lowell, MA, United States
| | - Steven L. Jacques
- Department of Bioengineering, University of Washington, Seattle, WA, United States
| | - Sidney Strickland
- Laboratory of Neurobiology and Genetics, The Rockefeller University, New York, NY, United States
| | - James G. Krueger
- Laboratory of Investigative Dermatology, The Rockefeller University, New York, NY, United States
| | - Hyung Jin Ahn
- Department of Pharmacology, Physiology and Neuroscience, Rutgers-New Jersey Medical School, Newark, NJ, United States
- Brain Health Institute, Rutgers University, Piscataway, NJ, United States
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Hayes G, Pinto J, Sparks SN, Wang C, Suri S, Bulte DP. Vascular smooth muscle cell dysfunction in neurodegeneration. Front Neurosci 2022; 16:1010164. [PMID: 36440263 PMCID: PMC9684644 DOI: 10.3389/fnins.2022.1010164] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 10/24/2022] [Indexed: 09/01/2023] Open
Abstract
Vascular smooth muscle cells (VSMCs) are the key moderators of cerebrovascular dynamics in response to the brain's oxygen and nutrient demands. Crucially, VSMCs may provide a sensitive biomarker for neurodegenerative pathologies where vasculature is compromised. An increasing body of research suggests that VSMCs have remarkable plasticity and their pathophysiology may play a key role in the complex process of neurodegeneration. Furthermore, extrinsic risk factors, including environmental conditions and traumatic events can impact vascular function through changes in VSMC morphology. VSMC dysfunction can be characterised at the molecular level both preclinically, and clinically ex vivo. However the identification of VSMC dysfunction in living individuals is important to understand changes in vascular function at the onset and progression of neurological disorders such as dementia, Alzheimer's disease, and Parkinson's disease. A promising technique to identify changes in the state of cerebral smooth muscle is cerebrovascular reactivity (CVR) which reflects the intrinsic dynamic response of blood vessels in the brain to vasoactive stimuli in order to modulate regional cerebral blood flow (CBF). In this work, we review the role of VSMCs in the most common neurodegenerative disorders and identify physiological systems that may contribute to VSMC dysfunction. The evidence collected here identifies VSMC dysfunction as a strong candidate for novel therapeutics to combat the development and progression of neurodegeneration, and highlights the need for more research on the role of VSMCs and cerebrovascular dynamics in healthy and diseased states.
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Affiliation(s)
- Genevieve Hayes
- Department of Engineering Science, Institute of Biomedical Engineering, University of Oxford, Oxford, United Kingdom
| | - Joana Pinto
- Department of Engineering Science, Institute of Biomedical Engineering, University of Oxford, Oxford, United Kingdom
| | - Sierra N. Sparks
- Department of Engineering Science, Institute of Biomedical Engineering, University of Oxford, Oxford, United Kingdom
| | - Congxiyu Wang
- Department of Psychiatry, University of Oxford, Oxford, United Kingdom
- Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, United Kingdom
| | - Sana Suri
- Department of Psychiatry, University of Oxford, Oxford, United Kingdom
- Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, United Kingdom
| | - Daniel P. Bulte
- Department of Engineering Science, Institute of Biomedical Engineering, University of Oxford, Oxford, United Kingdom
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3
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The role of the autonomic nervous system in cerebral blood flow regulation in dementia: A review. Auton Neurosci 2022; 240:102985. [DOI: 10.1016/j.autneu.2022.102985] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 02/28/2022] [Accepted: 04/28/2022] [Indexed: 11/19/2022]
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Beishon L, Panerai RB, Robinson TG, Haunton VJ. Cerebral blood flow response rate to task-activation using a novel method can discriminate cognitive impairment from healthy aging. Physiol Meas 2021; 42. [PMID: 34229305 DOI: 10.1088/1361-6579/ac1185] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 07/06/2021] [Indexed: 12/20/2022]
Abstract
Objective.A new method to classify individuals as 'responders' to task-activated cerebral blood flow velocity (CBFv) has recently been developed. This study investigated whether CBFv response rate to task-activation is affected by Alzheimer's disease (AD) and mild cognitive impairment (MCI).Approach.The 95th thresholds for cross correlation function peak and variance ratio were derived from 270 unstimulated, healthy hemispheres, and were used to classify the presence of a response to task-activation. Thresholds were applied to five cognitive tasks (attention, verbal fluency, language, visuospatial, memory) in CBFv data from 30 healthy older adults (HC), 35 AD and 22 MCI participants. Cumulative response rate (CRR) was calculated from the sum of responses across five tasks, for both hemispheres. Area under the curve (AUC) was derived from receiver operating characteristic (ROC) curve analysis.Main results. The number of responders differed significantly between tasks (p < 0.005) and diagnostic groups (p = 0.011). On post hoc tests there were more responders in the visuospatial (79%-90%) compared to fluency (45%-80%), language (50%-77%), and memory (44%-70%) tasks bilaterally, and responders were greater in the HC (70%) compared to AD (41%) and MCI (23%) groups to at least eight out of ten tasks. At an optimal threshold of 7.5 out of 10 responses, the AUC-ROC distinguished HC from AD and MCI with a; sensitivity 66% and specificity 70% (AUC = 0.72).Significance. Using a novel method to classify responders to cognitive task-activation, HC demonstrated a higher CRR than those with MCI or AD, and a threshold of <8 responses distinguished healthy ageing from dementia.
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Affiliation(s)
- Lucy Beishon
- University of Leicester, Department of Cardiovascular Sciences, Leicester, United Kingdom
| | - Ronney B Panerai
- University of Leicester, Department of Cardiovascular Sciences, Leicester, United Kingdom.,NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, United Kingdom
| | - Thompson G Robinson
- University of Leicester, Department of Cardiovascular Sciences, Leicester, United Kingdom.,NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, United Kingdom
| | - Victoria J Haunton
- University of Leicester, Department of Cardiovascular Sciences, Leicester, United Kingdom.,NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, United Kingdom
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Chen JJ. Cerebrovascular-Reactivity Mapping Using MRI: Considerations for Alzheimer's Disease. Front Aging Neurosci 2018; 10:170. [PMID: 29922153 PMCID: PMC5996106 DOI: 10.3389/fnagi.2018.00170] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 05/18/2018] [Indexed: 01/14/2023] Open
Abstract
Alzheimer’s disease (AD) is associated with well-established macrostructural and cellular markers, including localized brain atrophy and deposition of amyloid. However, there is growing recognition of the link between cerebrovascular dysfunction and AD, supported by continuous experimental evidence in the animal and human literature. As a result, neuroimaging studies of AD are increasingly aiming to incorporate vascular measures, exemplified by measures of cerebrovascular reactivity (CVR). CVR is a measure that is rooted in clinical practice, and as non-invasive CVR-mapping techniques become more widely available, routine CVR mapping may open up new avenues of investigation into the development of AD. This review focuses on the use of MRI to map CVR, paying specific attention to recent developments in MRI methodology and on the emerging stimulus-free approaches to CVR mapping. It also summarizes the biological basis for the vascular contribution to AD, and provides critical perspective on the choice of CVR-mapping techniques amongst frail populations.
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Affiliation(s)
- J J Chen
- Rotman Research Institute, Baycrest, Toronto, ON, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
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Lassila T, Di Marco LY, Mitolo M, Iaia V, Levedianos G, Venneri A, Frangi AF. Screening for Cognitive Impairment by Model-Assisted Cerebral Blood Flow Estimation. IEEE Trans Biomed Eng 2017; 65:1654-1661. [PMID: 28991728 DOI: 10.1109/tbme.2017.2759511] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Alzheimer's disease (AD) is a progressive and debilitating neurodegenerative disease; a major health concern in the ageing population with an estimated prevalence of 46 million dementia cases worldwide. Early diagnosis is therefore crucial so mitigating treatments can be initiated at an early stage. Cerebral hypoperfusion has been linked with blood-brain barrier dysfunction in the early stages of AD, and screening for chronic cerebral hypoperfusion in individuals has been proposed for improving the early diagnosis of AD. However, ambulatory measurements of cerebral blood flow are not routinely carried out in the clinical setting. In this study, we combine physiological modeling with Holter blood pressure monitoring and carotid ultrasound imaging to predict 24-h cerebral blood flow (CBF) profiles in individuals. One hundred and three participants [53 with mild cognitive impairment (MCI) and 50 healthy controls] underwent model-assisted prediction of 24-h CBF. Model-predicted CBF and neuropsychological tests were features in lasso regression models for MCI diagnosis. RESULTS A CBF-enhanced classifier for diagnosing MCI performed better, area-under-the-curve (AUC) = 0.889 (95%-CI: 0.800 to 0.978), than a classifier based only on the neuropsychological test scores, AUC = 0.818 (95%-CI: 0.643 to 0.992). An additional cohort of 25 participants (11 MCI and 14 healthy) was recruited to perform model validation by arterial spin-labeling magnetic resonance imaging, and to establish a link between measured CBF that predicted by the model. CONCLUSION Ultrasound imaging and ambulatory blood pressure measurements enhanced with physiological modeling can improve MCI diagnosis accuracy.
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Aanerud J, Borghammer P, Rodell A, Jónsdottir KY, Gjedde A. Sex differences of human cortical blood flow and energy metabolism. J Cereb Blood Flow Metab 2017; 37:2433-2440. [PMID: 27629099 PMCID: PMC5531342 DOI: 10.1177/0271678x16668536] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 06/29/2016] [Accepted: 07/04/2016] [Indexed: 11/16/2022]
Abstract
Brain energy metabolism is held to reflect energy demanding processes in neuropil related to the density and activity of synapses. There is recent evidence that men have higher density of synapses in temporal cortex than women. One consequence of these differences would be different rates of cortical energy turnover and blood flow in men and women. To test the hypotheses that rates of oxygen consumption (CMRO2) and cerebral blood flow are higher in men than in women in regions of cerebral cortex, and that the differences persist with aging, we used positron emission tomography to determine cerebral blood flow and cerebral metabolic rate of oxygen as functions of age in healthy volunteers of both sexes. Cerebral metabolic rate of oxygen did not change with age for either sex and there were no differences of mean values of cerebral metabolic rate of oxygen between men and women in cerebral cortex. Women had significant decreases of cerebral blood flow as function of age in frontal and parietal lobes. Young women had significantly higher cerebral blood flow than men in frontal and temporal lobes, but these differences had disappeared at age 65. The absent sex difference of cerebral energy turnover suggests that the known differences of synaptic density between the sexes are counteracted by opposite differences of individual synaptic activity.
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Affiliation(s)
- Joel Aanerud
- Department of Nuclear Medicine and PET Center, Aarhus University Hospitals, Aarhus, Denmark
| | - Per Borghammer
- Department of Nuclear Medicine and PET Center, Aarhus University Hospitals, Aarhus, Denmark
| | - Anders Rodell
- Centre for Clinical Research, University of Queensland, Australia
| | | | - Albert Gjedde
- Center for Functionally Integrative Neuroscience, University of Aarhus, Aarhus, Denmark
- Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
- Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, USA
- Department of Neurology and Neurosurgery, McGill University, Montréal, Québec, Canada
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Rodell AB, O'Keefe G, Rowe CC, Villemagne VL, Gjedde A. Cerebral Blood Flow and Aβ-Amyloid Estimates by WARM Analysis of [ 11C]PiB Uptake Distinguish among and between Neurodegenerative Disorders and Aging. Front Aging Neurosci 2017; 8:321. [PMID: 28123366 PMCID: PMC5225115 DOI: 10.3389/fnagi.2016.00321] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 12/12/2016] [Indexed: 11/13/2022] Open
Abstract
Background: We report results of the novel Washout Allometric Reference Method (WARM) that uses estimates of cerebral blood flow and amyloid load from the same [11C]Pittsburgh Compound B ([11C]PiB) retention maps in brain to distinguish between patients with different forms dementia, including Alzheimer's disease, and healthy volunteers. The method introduces two approaches to the identification of brain pathology related to amyloid accumulation, (1) a novel analysis of amyloid binding based on the late washout of the tracer from brain tissue, and (2) the simultaneous estimation of absolute cerebral blood flow indices (sCBF) from the early accumulation of the tracer in brain tissue. Objective: We tested the hypothesis that a change of cerebral blood flow is correlated with the degree of tracer [11C]PiB retention, reflecting dendritic spine pathology and consequent inhibition of brain energy metabolism and reduction of blood flow by neurovascular coupling in neurodegenerative disorders, including Alzheimer's disease. Methods: Previously reported images of [11C]PiB retention in brain of 29 subjects with cognitive impairment or dementia [16 Alzheimer's Disease (AD), eight subjects with dementia with Lewy bodies (DLB), five patients with frontotemporal lobar degeneration (FTLD), five patients with mild cognitive impairment, and 29 age-matched healthy control subjects (HC)], underwent analysis of PiB delivery and retention by means of WARM for quantitation of [11C]PiB's binding potentials (BPND) and correlated surrogate cerebral blood flow (sCBF) estimates, based on the [11C]PiB images, compared to estimates by conventional Standard Uptake Value Ratio (SUVR) of [11C]PiB retention with cerebellum gray matter as reference. Receiver Operating Characteristics (ROC) revealed the power of discrimination among estimates. Results: For AD, the discriminatory power of [11C]PiB binding potential (BPND) by WARM exceeded the power of SUVR that in turn exceeded the power of sCBF estimates. Differences of [11C]PiB binding and sCBF measures between AD and HC both were highly significant (p < 0.001). For all the dementia groups as a whole, sCBF estimates revealed the greatest discrimination between the patient and HC groups. WARM resolves a major issue of amyloid load quantification with [11C]PiB in human brain by determining absolute sCBF and amyloid load measures from the same images. The two parameter approach provides key discriminary information in AD for which [11C]PiB traditionally is used, as well as for the distinct flow deficits in FTLD, and the marked parietal and occipital lobe flow deficits in DLB. Conclusion: We conclude that WARM yields estimates of two important variables that together discriminate among patients with dementia, including AD, and healthy volunteers, with ROC that are superior to conventional methods of analysis. The distinction between estimates of flow and amyloid load from the same dynamic emission tomograms provides valuable pathogenetic information.
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Affiliation(s)
- Anders B Rodell
- Centre for Clinical Research, University of Queensland, BrisbaneQLD, Australia; Department of Nuclear Medicine & PET-Centre, Aarhus University HospitalAarhus, Denmark
| | - Graeme O'Keefe
- Department of Molecular Imaging and Therapy, Centre for PET, Austin Health, Heidelberg VIC, Australia
| | - Christopher C Rowe
- Department of Molecular Imaging and Therapy, Centre for PET, Austin Health, Heidelberg VIC, Australia
| | - Victor L Villemagne
- Department of Molecular Imaging and Therapy, Centre for PET, Austin Health, Heidelberg VIC, Australia
| | - Albert Gjedde
- Department of Neuroscience and Pharmacology, University of CopenhagenCopenhagen, Denmark; Department of Neurology and Neurosurgery, McGill University, MontréalQC, Canada; Division of Nuclear Medicine, Department of Radiology and Radiological Science, Johns Hopkins University, BaltimoreMD, USA; Neurosciences Research Center, Tabriz University of Medical SciencesTabriz, Iran; Department of Clinical Medicine - Department of Nuclear Medicine, University of Southern DenmarkOdense, Denmark
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Gejl M, Gjedde A, Egefjord L, Møller A, Hansen SB, Vang K, Rodell A, Brændgaard H, Gottrup H, Schacht A, Møller N, Brock B, Rungby J. In Alzheimer's Disease, 6-Month Treatment with GLP-1 Analog Prevents Decline of Brain Glucose Metabolism: Randomized, Placebo-Controlled, Double-Blind Clinical Trial. Front Aging Neurosci 2016; 8:108. [PMID: 27252647 PMCID: PMC4877513 DOI: 10.3389/fnagi.2016.00108] [Citation(s) in RCA: 265] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 04/26/2016] [Indexed: 12/11/2022] Open
Abstract
In animal models, the incretin hormone GLP-1 affects Alzheimer’s disease (AD). We hypothesized that treatment with GLP-1 or an analog of GLP-1 would prevent accumulation of Aβ and raise, or prevent decline of, glucose metabolism (CMRglc) in AD. In this 26-week trial, we randomized 38 patients with AD to treatment with the GLP-1 analog liraglutide (n = 18), or placebo (n = 20). We measured Aβ load in brain with tracer [11C]PIB (PIB), CMRglc with [18F]FDG (FDG), and cognition with the WMS-IV scale (ClinicalTrials.gov NCT01469351). The PIB binding increased significantly in temporal lobe in placebo and treatment patients (both P = 0.04), and in occipital lobe in treatment patients (P = 0.04). Regional and global increases of PIB retention did not differ between the groups (P ≥ 0.38). In placebo treated patients CMRglc declined in all regions, significantly so by the following means in precuneus (P = 0.009, 3.2 μmol/hg/min, 95% CI: 5.45; 0.92), and in parietal (P = 0.04, 2.1 μmol/hg/min, 95% CI: 4.21; 0.081), temporal (P = 0.046, 1.54 μmol/hg/min, 95% CI: 3.05; 0.030), and occipital (P = 0.009, 2.10 μmol/hg/min, 95% CI: 3.61; 0.59) lobes, and in cerebellum (P = 0.04, 1.54 μmol/hg/min, 95% CI: 3.01; 0.064). In contrast, the GLP-1 analog treatment caused a numerical but insignificant increase of CMRglc after 6 months. Cognitive scores did not change. We conclude that the GLP-1 analog treatment prevented the decline of CMRglc that signifies cognitive impairment, synaptic dysfunction, and disease evolution. We draw no firm conclusions from the Aβ load or cognition measures, for which the study was underpowered.
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Affiliation(s)
- Michael Gejl
- Institute of Biomedicine, Aarhus UniversityAarhus, Denmark; Department of Nuclear Medicine and PET Center, Aarhus University HospitalAarhus, Denmark
| | - Albert Gjedde
- Department of Nuclear Medicine and PET Center, Aarhus University HospitalAarhus, Denmark; Department of Neuroscience and Pharmacology, University of CopenhagenCopenhagen, Denmark
| | - Lærke Egefjord
- Institute of Biomedicine, Aarhus UniversityAarhus, Denmark; Department of Nuclear Medicine and PET Center, Aarhus University HospitalAarhus, Denmark
| | - Arne Møller
- Department of Nuclear Medicine and PET Center, Aarhus University Hospital Aarhus, Denmark
| | - Søren B Hansen
- Department of Nuclear Medicine and PET Center, Aarhus University Hospital Aarhus, Denmark
| | - Kim Vang
- Department of Nuclear Medicine and PET Center, Aarhus University Hospital Aarhus, Denmark
| | - Anders Rodell
- Department of Nuclear Medicine and PET Center, Aarhus University Hospital Aarhus, Denmark
| | - Hans Brændgaard
- Dementia Clinic, Department of Neurology, Aarhus University Hospital Aarhus, Denmark
| | - Hanne Gottrup
- Dementia Clinic, Department of Neurology, Aarhus University Hospital Aarhus, Denmark
| | - Anna Schacht
- Department of Nuclear Medicine and PET Center, Aarhus University Hospital Aarhus, Denmark
| | - Niels Møller
- Department of Endocrinology, Aarhus University Hospital Aarhus, Denmark
| | - Birgitte Brock
- Institute of Biomedicine, Aarhus UniversityAarhus, Denmark; Department of Clinical Biochemistry, Aarhus University HospitalAarhus, Denmark
| | - Jørgen Rungby
- Institute of Biomedicine, Aarhus UniversityAarhus, Denmark; Center for Diabetes Research and Department of Clinical Pharmacology, Copenhagen University Hospital Gentofte and RigshospitaletCopenhagen, Denmark
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10
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Janik R, Thomason LAM, Chaudhary S, Dorr A, Scouten A, Schwindt G, Masellis M, Stanisz GJ, Black SE, Stefanovic B. Attenuation of functional hyperemia to visual stimulation in mild Alzheimer's disease and its sensitivity to cholinesterase inhibition. Biochim Biophys Acta Mol Basis Dis 2015; 1862:957-65. [PMID: 26521151 DOI: 10.1016/j.bbadis.2015.10.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 10/21/2015] [Accepted: 10/25/2015] [Indexed: 01/09/2023]
Abstract
Despite the growing recognition of the significance of cerebrovascular impairment in the etiology and progression of Alzheimer's disease (AD), the early stage brain vascular dysfunction and its sensitivity to pharmacological interventions is still not fully characterized. Due to the early and aggressive treatment of probable AD with cholinesterase inhibitors (ChEI), which in and of themselves have direct effects on brain vasculature, the vast majority of hemodynamic measurements in early AD subjects reported hitherto have consequently been made only after the start of treatment, complicating the disentanglement of disease- vs. treatment-related effects on the cerebral vasculature. To address this gap, we used pseudo continuous arterial spin labeling MRI to measure resting perfusion and visual stimulation elicited changes in cerebral blood flow (CBF) and blood oxygenation dependent (BOLD) fMRI signal in a cohort of mild AD patients immediately prior to, 6months post, and 12months post commencement of open label cholinesterase inhibitor treatment. Although patients exhibited no gray matter atrophy prior to treatment and their resting perfusion was not distinguishable from that in age, education and gender-matched controls, the patients' visual stimulation-elicited changes in BOLD fMRI and blood flow were decreased by 10±4% (BOLD) and 23±2% (CBF), relative to those in controls. Induction of cholinesterase inhibition treatment was associated with a further, 7±2% reduction in patients' CBF response to visual stimulation, but it stabilized, at this new lower level, over the follow-up period. Likewise, MMSE scores remained stable during the treatment; furthermore, higher MMSE scores were associated with higher perfusion responses to visual stimulation. This study represents the initial step in disentangling the effects of AD pathology from those of the first line treatment with cholinesterase inhibitors on cerebral hemodynamics and supports the use of arterial spin labeling MRI for quantitative evaluation of the brain vascular function in mild Alzheimer's disease. The findings provide evidence of a pronounced deficit in the visual cortex hyperemia despite the relative sparing of visual function in early stage AD, its reduction with ChEI treatment induction, and its stabilization in the first year of cholinesterase inhibition treatment. This article is part of a Special Issue entitled: Vascular Contributions to Cognitive Impairment and Dementia edited by M. Paul Murphy, Roderick A. Corriveau and Donna M. Wilcock.
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Affiliation(s)
- Rafal Janik
- Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada; Department of Medical Biophysics, University of Toronto, 610 University Avenue, Toronto, ON M5G 2M9, Canada.
| | - Lynsie A M Thomason
- Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada
| | - Simone Chaudhary
- Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada; Department of Medical Biophysics, University of Toronto, 610 University Avenue, Toronto, ON M5G 2M9, Canada
| | - Adrienne Dorr
- Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada
| | - Amy Scouten
- Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada; Department of Medical Biophysics, University of Toronto, 610 University Avenue, Toronto, ON M5G 2M9, Canada
| | - Graeme Schwindt
- Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada
| | - Mario Masellis
- Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada; Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada
| | - Greg J Stanisz
- Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada; Department of Medical Biophysics, University of Toronto, 610 University Avenue, Toronto, ON M5G 2M9, Canada; Department of Nerurosurgery and Pediatrics Neurosurgery, Medical University of Lublin, Aleje Raclawickie 1, 20-059 Lublin, Poland
| | - Sandra E Black
- Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada; Institute of Medical Sciences, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada; Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada; Department of Medicine (Neurology), Sunnybrook Health Sciences Centre University of Toronto, Canada; Canadian Partnership for Stroke Recovery Sunnybrook Site, Canada
| | - Bojana Stefanovic
- Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada; Department of Medical Biophysics, University of Toronto, 610 University Avenue, Toronto, ON M5G 2M9, Canada; Canadian Partnership for Stroke Recovery Sunnybrook Site, Canada
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11
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Rodell A, Aanerud J, Braendgaard H, Gjedde A. Washout allometric reference method (WARM) for parametric analysis of [(11)C]PIB in human brains. Front Aging Neurosci 2013; 5:45. [PMID: 24348416 PMCID: PMC3842163 DOI: 10.3389/fnagi.2013.00045] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Accepted: 11/07/2013] [Indexed: 01/28/2023] Open
Abstract
Rapid clearance and disappearance of a tracer from the circulation challenges the determination of the tracer's binding potentials in brain (BPND) by positron emission tomography (PET). This is the case for the analysis of the binding of radiolabeled [11C]Pittsburgh Compound B ([11C]PIB) to amyloid-β (Aβ) plaques in brain of patients with Alzheimer's disease (AD). To resolve the issue of rapid clearance from the circulation, we here introduce the flow-independent Washout Allometric Reference Method (WARM) for the analysis of washout and binding of [11C]PIB in two groups of human subjects, healthy aged control subjects (HC), and patients suffering from AD, and we compare the results to the outcome of two conventional analysis methods. We also use the rapid initial clearance to obtain a surrogate measure of the rate of cerebral blood flow (CBF), as well as a method of identifying a suitable reference region directly from the [11C]PIB signal. The difference of average absolute CBF values between the AD and HC groups was highly significant (P < 0.003). The CBF measures were not significantly different between the groups when normalized to cerebellar gray matter flow. Thus, when flow differences confound conventional measures of [11C]PIB binding, the separate estimates of CBF and BPND provide additional information about possible AD. The results demonstrate the importance of data-driven estimation of CBF and BPND, as well as reference region detection from the [11C]PIB signal. We conclude that the WARM method yields stable measures of BPND with relative ease, using only integration for noise reduction and no model regression. The method accounts for relative flow differences in the brain tissue and yields a calibrated measure of absolute CBF directly from the [11C]PIB signal. Compared to conventional methods, WARM optimizes the Aβ plaque load discrimination between patients with AD and healthy controls (P = 0.009).
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Affiliation(s)
- Anders Rodell
- Department of Nuclear Medicine and PET Centre, Aarhus University Hospital Aarhus, Denmark
| | - Joel Aanerud
- Department of Nuclear Medicine and PET Centre, Aarhus University Hospital Aarhus, Denmark
| | - Hans Braendgaard
- Department of Neurology, Aarhus University Hospital Aarhus, Denmark
| | - Albert Gjedde
- Department of Nuclear Medicine and PET Centre, Aarhus University Hospital Aarhus, Denmark ; Department of Neuroscience and Pharmacology, University of Copenhagen Copenhagen, Denmark
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Gjedde A, Aanerud J, Braendgaard H, Rodell AB. Blood-brain transfer of Pittsburgh compound B in humans. Front Aging Neurosci 2013; 5:70. [PMID: 24223554 PMCID: PMC3819578 DOI: 10.3389/fnagi.2013.00070] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Accepted: 10/19/2013] [Indexed: 11/13/2022] Open
Abstract
In the labeled form, the Pittsburgh compound B (2-(4′-{N-methyl-[11C]}methyl-aminophenyl)-6-hydroxy-benzothiazole, [11C]PiB), is used as a biomarker for positron emission tomography (PET) of brain β-amyloid deposition in Alzheimer's disease (AD). The permeability of [11C]PiB in the blood-brain barrier is held to be high but the permeability-surface area product and extraction fractions in patients or healthy volunteers are not known. We used PET to determine the clearance associated with the unidrectional blood-brain transfer of [11C]PiB and the corresponding cerebral blood flow rates in frontal lobe, whole cerebral cortex, and cerebellum of patients with Alzheimer's disease and healthy volunteers. Regional cerebral blood flow rates differed significantly between the two groups. Thus, regional and whole-brain permeability-surface area products were identical, in agreement with the observation that numerically, but insignificantly, unidirectional blood-brain clearances are lower and extraction fractions higher in the patients. The evidence of unchanged permeability-surface area products in the patients implies that blood flow changes can be deduced from the unidirectional blood-brain clearances of [11C]PiB in the patients.
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Affiliation(s)
- Albert Gjedde
- Department of Neuroscience and Pharmacology, University of Copenhagen Copenhagen, Denmark ; Department of Nuclear Medicine and PET Centre, Aarhus University Hospital Aarhus, Denmark ; Center of Functionally Integrative Neuroscience, Faculty of Health, Aarhus University Aarhus, Denmark ; Department of Neurology, McGill University Montreal, QC, Canada ; Department of Radiology and Radiological Science, Johns Hopkins University Baltimore, MD, USA
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Glodzik L, Randall C, Rusinek H, de Leon MJ. Cerebrovascular reactivity to carbon dioxide in Alzheimer's disease. J Alzheimers Dis 2013; 35:427-40. [PMID: 23478306 DOI: 10.3233/jad-122011] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
There is growing evidence that cerebrovascular reactivity to carbon dioxide (CVRCO2) is impaired in Alzheimer's disease (AD). Preclinical and animal studies suggest chronic hypercontractility in brain vessels in AD. We review (a) preclinical studies of mechanisms for impaired CVRCO2 in AD; (b) clinical studies of cerebrovascular function in subjects with AD dementia, mild cognitive impairment (MCI), and normal cognition. Although results of clinical studies are inconclusive, an increasing number of reports reveal an impairment of vascular reactivity to carbon dioxide in subjects with AD, and possibly also in MCI. Thus, CVRCO2 may be an attractive means to detect an early vascular dysfunction in subjects at risk.
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Affiliation(s)
- Lidia Glodzik
- Center for Brain Health, Department of Psychiatry, New York University School of Medicine, New York, NY 10016, USA.
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Tissue oxygen saturation and pulsatility index as markers for amnestic mild cognitive impairment: NIRS and TCD study. Clin Neurophysiol 2013; 124:851-6. [DOI: 10.1016/j.clinph.2012.11.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2012] [Revised: 11/11/2012] [Accepted: 11/19/2012] [Indexed: 02/02/2023]
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