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Cho J, Zhang J, Spincemaille P, Zhang H, Nguyen TD, Zhang S, Gupta A, Wang Y. Multi-Echo Complex Quantitative Susceptibility Mapping and Quantitative Blood Oxygen Level-Dependent Magnitude (mcQSM + qBOLD or mcQQ) for Oxygen Extraction Fraction (OEF) Mapping. Bioengineering (Basel) 2024; 11:131. [PMID: 38391617 PMCID: PMC10886243 DOI: 10.3390/bioengineering11020131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 01/25/2024] [Accepted: 01/26/2024] [Indexed: 02/24/2024] Open
Abstract
Oxygen extraction fraction (OEF), the fraction of oxygen that tissue extracts from blood, is an essential biomarker used to directly assess tissue viability and function in neurologic disorders. In ischemic stroke, for example, increased OEF can indicate the presence of penumbra-tissue with low perfusion yet intact cellular integrity-making it a primary therapeutic target. However, practical OEF mapping methods are not currently available in clinical settings, owing to the impractical data acquisitions in positron emission tomography (PET) and the limitations of existing MRI techniques. Recently, a novel MRI-based OEF mapping technique, termed QQ, was proposed. It shows high potential for clinical use by utilizing a routine sequence and removing the need for impractical multiple gas inhalations. However, QQ relies on the assumptions of Gaussian noise in susceptibility and multi-echo gradient echo (mGRE) magnitude signals for OEF estimation. This assumption is unreliable in low signal-to-noise ratio (SNR) regions like disease-related lesions, risking inaccurate OEF estimation and potentially impacting clinical decisions. Addressing this, our study presents a novel multi-echo complex QQ (mcQQ) that models realistic Gaussian noise in mGRE complex signals. We implemented mcQQ using a deep learning framework (mcQQ-NET) and compared it with the existing QQ-NET in simulations, ischemic stroke patients, and healthy subjects, using identical training and testing datasets and schemes. In simulations, mcQQ-NET provided more accurate OEF than QQ-NET. In the subacute stroke patients, mcQQ-NET showed a lower average OEF ratio in lesions relative to unaffected contralateral normal tissue than QQ-NET. In the healthy subjects, mcQQ-NET provided uniform OEF maps, similar to QQ-NET, but without unrealistically high OEF outliers in areas of low SNR, such as SNR ≤ 15 (dB). Therefore, mcQQ-NET improves OEF accuracy by more accurately reflecting realistic Gaussian noise in complex mGRE signals. Its enhanced sensitivity to OEF abnormalities, based on more realistic biophysics modeling, suggests that mcQQ-NET has potential for investigating tissue variability in neurologic disorders.
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Affiliation(s)
- Junghun Cho
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY 14228, USA
| | - Jinwei Zhang
- Department of Radiology, Weill Cornell Medicine, New York, NY 10065, USA
| | | | - Hang Zhang
- Department of Radiology, Weill Cornell Medicine, New York, NY 10065, USA
| | - Thanh D Nguyen
- Department of Radiology, Weill Cornell Medicine, New York, NY 10065, USA
| | - Shun Zhang
- Department of Radiology, Weill Cornell Medicine, New York, NY 10065, USA
| | - Ajay Gupta
- Department of Radiology, Weill Cornell Medicine, New York, NY 10065, USA
| | - Yi Wang
- Department of Radiology, Weill Cornell Medicine, New York, NY 10065, USA
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Lin Z, Lim C, Jiang D, Soldan A, Pettigrew C, Oishi K, Zhu Y, Moghekar A, Liu P, Albert M, Lu H. Longitudinal changes in brain oxygen extraction fraction (OEF) in older adults: Relationship to markers of vascular and Alzheimer's pathology. Alzheimers Dement 2023; 19:569-577. [PMID: 35791732 PMCID: PMC10838398 DOI: 10.1002/alz.12727] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 05/18/2022] [Accepted: 05/31/2022] [Indexed: 11/07/2022]
Abstract
INTRODUCTION Oxygen extraction fraction (OEF) reflects the balance between oxygen delivery and consumption. We longitudinally measured OEF in older adults to examine the relationship with markers of Alzheimer's disease (AD) and vascular pathology. METHODS One hundred thirty-seven participants were studied at two time-points at an interval of 2.16 years. OEF was measured using T2 -relaxation-under-spin-tagging (TRUST) magnetic resonance imaging (MRI). The association between OEF and vascular risks, white matter hyperintensities (WMH), cerebrospinal fluid (CSF) measures of amyloid beta (Aβ), total tau (t-tau), and phosphorylated tau 181 (p-tau181) was examined. RESULTS OEF increased from baseline to follow-up. The increase in OEF was more prominent in individuals with high vascular risks compared to those with low vascular risks, and was associated with progression of vascular risks and the growth in WMH volume. OEF change was not related to CSF markers of AD pathology or their progression. DISCUSSION Longitudinal OEF change in older adults is primarily related to vascular pathology.
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Affiliation(s)
- Zixuan Lin
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Chantelle Lim
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Dengrong Jiang
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Anja Soldan
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Corinne Pettigrew
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Kumiko Oishi
- Center for Imaging Science, Whiting School of Engineering, Johns Hopkins University, Baltimore, Maryland, USA
| | - Yuxin Zhu
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Abhay Moghekar
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Peiying Liu
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Marilyn Albert
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Hanzhang Lu
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
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Gonzalez-Marrero I, Hernández-Abad LG, Castañeyra-Ruiz L, Carmona-Calero EM, Castañeyra-Perdomo A. Changes in the choroid plexuses and brain barriers associated with high blood pressure and ageing. Neurologia 2022; 37:371-382. [PMID: 30060976 DOI: 10.1016/j.nrl.2018.06.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 05/29/2018] [Accepted: 06/11/2018] [Indexed: 01/12/2023] Open
Abstract
INTRODUCTION The choroid plexuses, blood vessels, and brain barriers are closely related both in terms of morphology and function. Hypertension causes changes in cerebral blood flow and in small vessels and capillaries of the brain. This review studies the effects of high blood pressure (HBP) on the choroid plexuses and brain barriers. DEVELOPMENT The choroid plexuses (ChP) are structures located in the cerebral ventricles, and are highly conserved both phylogenetically and ontogenetically. The ChPs develop during embryogenesis, forming a functional barrier during the first weeks of gestation. They are composed of highly vascularised epithelial tissue covered by microvilli, and their main function is cerebrospinal fluid (CSF) production. The central nervous system (CNS) is protected by the blood-brain barrier (BBB) and the blood-CSF barrier (BCSFB). While the BBB is formed by endothelial cells of the microvasculature of the CNS, the BCSFB is formed by epithelial cells of the choroid plexuses. Chronic hypertension induces vascular remodelling. This prevents hyperperfusion at HBPs, but increases the risk of ischaemia at low blood pressures. In normotensive individuals, in contrast, cerebral circulation is self-regulated, blood flow remains constant, and the integrity of the BBB is preserved. CONCLUSIONS HBP induces changes in the choroid plexuses that affect the stroma, blood vessels, and CSF production. HBP also exacerbates age-related ChP dysfunction and causes alterations in the brain barriers, which are more marked in the BCSFB than in the BBB. Brain barrier damage may be determined by quantifying blood S-100β and TTRm levels.
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Affiliation(s)
- I Gonzalez-Marrero
- Departamento de Anatomía, Facultad de Medicina, Universidad de La Laguna, La Laguna, Tenerife, España
| | - L G Hernández-Abad
- Instituto de Investigación y Ciencias de Puerto de Rosario, Puerto del Rosario, Fuerteventura, España
| | - L Castañeyra-Ruiz
- Departamento de Anatomía, Facultad de Medicina, Universidad de La Laguna, La Laguna, Tenerife, España; Departamento de Farmacología, Facultad de Medicina, Universidad de La Laguna, La Laguna, Tenerife, España
| | - E M Carmona-Calero
- Departamento de Anatomía, Facultad de Medicina, Universidad de La Laguna, La Laguna, Tenerife, España; Instituto de Investigación y Ciencias de Puerto de Rosario, Puerto del Rosario, Fuerteventura, España
| | - A Castañeyra-Perdomo
- Departamento de Anatomía, Facultad de Medicina, Universidad de La Laguna, La Laguna, Tenerife, España; Instituto de Investigación y Ciencias de Puerto de Rosario, Puerto del Rosario, Fuerteventura, España.
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Jiang D, Lin Z, Liu P, Sur S, Xu C, Hazel K, Pottanat G, Darrow J, Pillai JJ, Yasar S, Rosenberg P, Moghekar A, Albert M, Lu H. Brain Oxygen Extraction Is Differentially Altered by Alzheimer's and Vascular Diseases. J Magn Reson Imaging 2020; 52:1829-1837. [PMID: 32567195 PMCID: PMC9973301 DOI: 10.1002/jmri.27264] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 06/02/2020] [Accepted: 06/03/2020] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Alzheimer's disease and vascular cognitive impairment (VCI), as well as their concurrence, represent the most common types of cognitive dysfunction. Treatment strategies for these two conditions are quite different; however, there exists a considerable overlap in their clinical manifestations, and most biomarkers reveal similar abnormalities between these two conditions. PURPOSE To evaluate the potential of cerebral oxygen extraction fraction (OEF) as a biomarker for differential diagnosis of Alzheimer's disease and VCI. We hypothesized that in Alzheimer's disease OEF will be reduced (decreased oxygen consumption due to decreased neural activity), while in vascular diseases OEF will be elevated (increased oxygen extraction due to abnormally decreased blood flow). STUDY TYPE Prospective cross-sectional. POPULATION Sixty-five subjects aged 52-89 years, including 33 mild cognitive impairment (MCI), 7 dementia, and 25 cognitively normal subjects. FIELD STRENGTH/SEQUENCE 3T T2 -relaxation-under-spin-tagging (TRUST) and fluid-attenuated inversion recovery imaging (FLAIR). ASSESSMENT OEF, consensus diagnoses of cognitive impairment, vascular risk factors (such as hypertension, hypercholesterolemia, diabetes, smoking, and obesity), cognitive assessments, and cerebrospinal fluid concentration of amyloid and tau were assessed. STATISTICAL TESTS Multiple linear regression analyses of OEF with diagnostic category (normal, MCI, or dementia), vascular risks, cognitive performance, amyloid and tau pathology. RESULTS When evaluating the entire group, OEF was found to be lower with more severe cognitive impairment (β = -2.70 ± 1.15, T = -2.34, P = 0.02), but was higher with greater vascular risk factors (β = 1.36 ± 0.55, T = 2.48, P = 0.02). Further investigation of the subgroup of participants with low vascular risks (N = 44) revealed that lower OEF was associated with worse cognitive performance (β = 0.04 ± 0.01, T = 3.27, P = 0.002) and greater amyloid burden (β = 92.12 ± 41.23, T = 2.23, P = 0.03). Among cognitively impaired individuals (N = 40), higher OEF was associated with greater vascular risk factors (β = 2.19 ± 0.71, T = 3.08, P = 0.004). DATA CONCLUSION These findings suggest that OEF is differentially affected by Alzheimer's disease and VCI pathology and may be useful in etiology-based diagnosis of cognitive impairment. LEVEL OF EVIDENCE 1 TECHNICAL EFFICACY: Stage 3 J. MAGN. RESON. IMAGING 2020;52:1829-1837.
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Affiliation(s)
- Dengrong Jiang
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Zixuan Lin
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Peiying Liu
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Sandeepa Sur
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Cuimei Xu
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Kaisha Hazel
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - George Pottanat
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Jacqueline Darrow
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Jay J. Pillai
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Sevil Yasar
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Paul Rosenberg
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Abhay Moghekar
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Marilyn Albert
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Hanzhang Lu
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, Maryland, USA
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Changes in the choroid plexuses and brain barriers associated with high blood pressure and ageing. NEUROLOGÍA (ENGLISH EDITION) 2020; 37:371-382. [DOI: 10.1016/j.nrleng.2020.05.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 06/11/2018] [Indexed: 01/04/2023] Open
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Parikh I, Guo J, Chuang KH, Zhong Y, Rempe RG, Hoffman JD, Armstrong R, Bauer B, Hartz AMS, Lin AL. Caloric restriction preserves memory and reduces anxiety of aging mice with early enhancement of neurovascular functions. Aging (Albany NY) 2017; 8:2814-2826. [PMID: 27829242 PMCID: PMC5191872 DOI: 10.18632/aging.101094] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 10/15/2016] [Indexed: 01/01/2023]
Abstract
Neurovascular integrity plays an important role in protecting cognitive and mental health in aging. Lifestyle interventions that sustain neurovascular integrity may thus be critical on preserving brain functions in aging and reducing the risk for age-related neurodegenerative disorders. Here we show that caloric restriction (CR) had an early effect on neurovascular enhancements, and played a critical role in preserving vascular, cognitive and mental health in aging. In particular, we found that CR significantly enhanced cerebral blood flow (CBF) and blood-brain barrier function in young mice at 5-6 months of age. The neurovascular enhancements were associated with reduced mammalian target of rapamycin expression, elevated endothelial nitric oxide synthase signaling, and increased ketone bodies utilization. With age, CR decelerated the rate of decline in CBF. The preserved CBF in hippocampus and frontal cortex were highly correlated with preserved memory and learning, and reduced anxiety, of the aging mice treated with CR (18-20 months of age). Our results suggest that dietary intervention started in the early stage (e.g., young adults) may benefit cognitive and mental reserve in aging. Understanding nutritional effects on neurovascular functions may have profound implications in human brain aging and age-related neurodegenerative disorders.
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Affiliation(s)
- Ishita Parikh
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY 40536, USA.,Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY 40536, USA
| | - Janet Guo
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY 40536, USA
| | - Kai-Hsiang Chuang
- Queensland Brain Institute and Centre for Advanced Imaging, University of Queensland, Brisbane, QLD 4072, Australia
| | - Yu Zhong
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY 40536, USA
| | - Ralf G Rempe
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY 40536, USA
| | - Jared D Hoffman
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY 40536, USA.,Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY 40536, USA
| | - Rachel Armstrong
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY 40536, USA
| | - Björn Bauer
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY 40536, USA
| | - Anika M S Hartz
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY 40536, USA.,Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY 40536, USA
| | - Ai-Ling Lin
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY 40536, USA.,Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY 40536, USA.,Department of Biomedical Engineering, University of Kentucky, Lexington, KY 40506, USA
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Lajoie I, Nugent S, Debacker C, Dyson K, Tancredi FB, Badhwar A, Belleville S, Deschaintre Y, Bellec P, Doyon J, Bocti C, Gauthier S, Arnold D, Kergoat MJ, Chertkow H, Monchi O, Hoge RD. Application of calibrated fMRI in Alzheimer's disease. NEUROIMAGE-CLINICAL 2017; 15:348-358. [PMID: 28560160 PMCID: PMC5443910 DOI: 10.1016/j.nicl.2017.05.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2017] [Revised: 04/26/2017] [Accepted: 05/15/2017] [Indexed: 02/07/2023]
Abstract
Calibrated fMRI based on arterial spin-labeling (ASL) and blood oxygen-dependent contrast (BOLD), combined with periods of hypercapnia and hyperoxia, can provide information on cerebrovascular reactivity (CVR), resting blood flow (CBF), oxygen extraction fraction (OEF), and resting oxidative metabolism (CMRO2). Vascular and metabolic integrity are believed to be affected in Alzheimer's disease (AD), thus, the use of calibrated fMRI in AD may help understand the disease and monitor therapeutic responses in future clinical trials. In the present work, we applied a calibrated fMRI approach referred to as Quantitative O2 (QUO2) in a cohort of probable AD dementia and age-matched control participants. The resulting CBF, OEF and CMRO2 values fell within the range from previous studies using positron emission tomography (PET) with 15O labeling. Moreover, the typical parietotemporal pattern of hypoperfusion and hypometabolism in AD was observed, especially in the precuneus, a particularly vulnerable region. We detected no deficit in frontal CBF, nor in whole grey matter CVR, which supports the hypothesis that the effects observed were associated specifically with AD rather than generalized vascular disease. Some key pitfalls affecting both ASL and BOLD methods were encountered, such as prolonged arterial transit times (particularly in the occipital lobe), the presence of susceptibility artifacts obscuring medial temporal regions, and the challenges associated with the hypercapnic manipulation in AD patients and elderly participants. The present results are encouraging and demonstrate the promise of calibrated fMRI measurements as potential biomarkers in AD. Although CMRO2 can be imaged with 15O PET, the QUO2 method uses more widely available imaging infrastructure, avoids exposure to ionizing radiation, and integrates with other MRI-based measures of brain structure and function.
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Affiliation(s)
- Isabelle Lajoie
- Département de Pharmacologie et physiologie, Université de Montréal, Montreal, QC, Canada; Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, Montreal, QC, Canada; Montreal Neurological Institute, Montreal, QC, Canada.
| | - Scott Nugent
- Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, Montreal, QC, Canada; Montreal Neurological Institute, Montreal, QC, Canada; Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
| | - Clément Debacker
- Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, Montreal, QC, Canada; Montreal Neurological Institute, Montreal, QC, Canada; Department of Psychiatry, McGill University, Montreal, QC, Canada
| | - Kenneth Dyson
- Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, Montreal, QC, Canada; Montreal Neurological Institute, Montreal, QC, Canada; Department of Physiology, McGill University, Montreal, QC, Canada
| | - Felipe B Tancredi
- Departamento de Radiologia, Centro de Pesquisa em Imagem, Hospital Israelita Albert Einstein, São Palo, SP, Brazil
| | - AmanPreet Badhwar
- Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, Montreal, QC, Canada; Department of Computer Science and Operations Research, Université de Montréal, Montreal, QC, Canada
| | - Sylvie Belleville
- Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, Montreal, QC, Canada; Département de Psychologie, Université de Montréal, Montreal, QC, Canada
| | - Yan Deschaintre
- Département de Neurosciences, Université de Montréal, Montreal, QC, Canada; Service de neurologie, Département de Médecine, CHUM Notre-Dame, Montréal, QC, Canada
| | - Pierre Bellec
- Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, Montreal, QC, Canada; Department of Computer Science and Operations Research, Université de Montréal, Montreal, QC, Canada
| | - Julien Doyon
- Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, Montreal, QC, Canada; Département de Psychologie, Université de Montréal, Montreal, QC, Canada
| | - Christian Bocti
- Division de Neurologie, Faculté de Médecine et des Sciences de la Santé & Research Centre on Aging, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Serge Gauthier
- McGill Center for Studies in Aging, Douglas Mental Health Research Institute, Montreal, QC, Canada
| | - Douglas Arnold
- Montreal Neurological Institute, Montreal, QC, Canada; Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
| | - Marie-Jeanne Kergoat
- Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, Montreal, QC, Canada; Département de Médecine, Université de Montréal, Montreal, QC, Canada
| | - Howard Chertkow
- Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, Montreal, QC, Canada; Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada; Department of Medicine, Sir Mortimer B. Davis-Jewish General Hospital, McGill University, Montreal, QC, Canada
| | - Oury Monchi
- Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, Montreal, QC, Canada; Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada; McGill Center for Studies in Aging, Douglas Mental Health Research Institute, Montreal, QC, Canada; Department of Clinical Neurosciences and Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Richard D Hoge
- Département de Pharmacologie et physiologie, Université de Montréal, Montreal, QC, Canada; Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, Montreal, QC, Canada; Montreal Neurological Institute, Montreal, QC, Canada; Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
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Lin AL, Jahrling JB, Zhang W, DeRosa N, Bakshi V, Romero P, Galvan V, Richardson A. Rapamycin rescues vascular, metabolic and learning deficits in apolipoprotein E4 transgenic mice with pre-symptomatic Alzheimer's disease. J Cereb Blood Flow Metab 2017; 37:217-226. [PMID: 26721390 PMCID: PMC5167110 DOI: 10.1177/0271678x15621575] [Citation(s) in RCA: 113] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 09/30/2015] [Accepted: 11/05/2015] [Indexed: 12/03/2022]
Abstract
Apolipoprotein E ɛ4 allele is a common susceptibility gene for late-onset Alzheimer's disease. Brain vascular and metabolic deficits can occur in cognitively normal apolipoprotein E ɛ4 carriers decades before the onset of Alzheimer's disease. The goal of this study was to determine whether early intervention using rapamycin could restore neurovascular and neurometabolic functions, and thus impede pathological progression of Alzheimer's disease-like symptoms in pre-symptomatic Apolipoprotein E ɛ4 transgenic mice. Using in vivo, multimodal neuroimaging, we found that apolipoprotein E ɛ4 mice treated with rapamycin had restored cerebral blood flow, blood-brain barrier integrity and glucose metabolism, compared to age- and gender-matched wild-type controls. The preserved vasculature and metabolism were associated with amelioration of incipient learning deficits. We also found that rapamycin restored the levels of the proinflammatory cyclophilin A in vasculature, which may contribute to the preservation of cerebrovascular function in the apolipoprotein E ɛ4 transgenics. Our results show that rapamycin improves functional outcomes in this mouse model and may have potential as an effective intervention to block progression of vascular, metabolic and early cognitive deficits in human Apolipoprotein E ɛ4 carriers. As rapamycin is FDA-approved and neuroimaging is readily used in humans, the results of the present study may provide the basis for future Alzheimer's disease intervention studies in human subjects.
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Affiliation(s)
- Ai-Ling Lin
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA .,Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA.,Department of Biomedical Engineering, University of Kentucky, Lexington, KY, USA
| | - Jordan B Jahrling
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.,Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Wei Zhang
- Research Imaging Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Nicholas DeRosa
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.,Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Vikas Bakshi
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA
| | - Peter Romero
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Veronica Galvan
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.,Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Arlan Richardson
- Geriatric Medicine, University of Oklahoma Health Science Center and Oklahoma City VA Medical Center, Oklahoma City, OK, USA
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Griffith CM, Macklin LN, Bartke A, Patrylo PR. Differential Fasting Plasma Glucose and Ketone Body Levels in GHRKO versus 3xTg-AD Mice: A Potential Contributor to Aging-Related Cognitive Status? Int J Endocrinol 2017; 2017:9684061. [PMID: 28638409 PMCID: PMC5468562 DOI: 10.1155/2017/9684061] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Cognitive function declines with age and appears to correlate with decreased cerebral metabolic rate (CMR). Caloric restriction, an antiaging manipulation that extends life-span and can preserve cognitive function, is associated with decreased glucose uptake, decreased lactate levels, and increased ketone body (KB) levels in the brain. Since the majority of brain nutrients come from the periphery, this study examined whether the capacity to regulate peripheral glucose levels and KB production differs in animals with successful cognitive aging (growth hormone receptor knockouts, GHRKOs) versus unsuccessful cognitive aging (the 3xTg-AD mouse model of Alzheimer's disease). Animals were fasted for 5 hours with their plasma glucose and KB levels subsequently measured. Intriguingly, in GHRKO mice, compared to those in controls, fasting plasma glucose levels were significantly decreased while their KB levels were significantly increased. Conversely, 3xTg-AD mice, compared to controls, exhibited significantly elevated plasma glucose levels and significantly reduced plasma KB levels. Taken together, these results suggest that the capacity to provide the brain with KBs versus glucose throughout an animal's life could somehow help preserve cognitive function with age, potentially through minimizing overall brain exposure to reactive oxygen species and advanced glycation end products and improving mitochondrial function.
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Affiliation(s)
- Chelsea M. Griffith
- Department of Physiology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
- Center for Integrated Research in Cognitive and Neural Sciences, Southern Illinois University, Carbondale, IL 62901, USA
| | - Lauren N. Macklin
- Department of Physiology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
- Center for Integrated Research in Cognitive and Neural Sciences, Southern Illinois University, Carbondale, IL 62901, USA
| | - Andrzej Bartke
- Division of Geriatrics Research, Department of Internal Medicine, Southern Illinois University School of Medicine, P.O. Box 19628, Springfield, IL 62794-9628, USA
| | - Peter R. Patrylo
- Department of Physiology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
- Center for Integrated Research in Cognitive and Neural Sciences, Southern Illinois University, Carbondale, IL 62901, USA
- Department of Anatomy, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
- *Peter R. Patrylo:
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Nagata K, Yamazaki T, Takano D, Maeda T, Fujimaki Y, Nakase T, Sato Y. Cerebral circulation in aging. Ageing Res Rev 2016; 30:49-60. [PMID: 27484894 DOI: 10.1016/j.arr.2016.06.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 05/31/2016] [Accepted: 06/01/2016] [Indexed: 12/20/2022]
Abstract
Cerebral circulation is known to be protected by the regulatory function against the hypoperfusion that will affect the cognitive function as a result of brain ischemia and energy failure. The regulatory function includes cerebrovascular autoregulation, chemical control, metabolic control, and neurogenic control, and those compensatory mechanisms can be influenced by hypertension, atherosclerosis, cardiac diseases, cerebrovascular diseases and aging. On the other hand, large and/or small infarction, intracranial hemorrhage, subarachnoid hemorrhage, atherosclerosis, amylod angiopathy are also more directly associated with cognitive decline not only in those with vascular cognitive impairment or vascular dementia but also those with Alzheimer's disease.
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Affiliation(s)
- Ken Nagata
- Department of Neurology, Clinical Research Institute, Yokohama General Hospital, Yokohama, Japan.
| | - Takashi Yamazaki
- Department of Neurology, Clinical Research Institute, Yokohama General Hospital, Yokohama, Japan
| | - Daiki Takano
- Department of Neurology, Clinical Research Institute, Yokohama General Hospital, Yokohama, Japan
| | - Tetsuya Maeda
- Department of Neurology and Gerontology, Iwate Medical University, Morioka, Japan
| | - Yumi Fujimaki
- Department of Neurology, Research Institute for Brain and Blood Vessels, Akita, Japan
| | - Taizen Nakase
- Department of Neurology, Research Institute for Brain and Blood Vessels, Akita, Japan
| | - Yuichi Sato
- Department of Neurology, Noshiro Yamamoto Medical Association Hospital, Noshiro, Japan
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11
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Lin AL, Zhang W, Gao X, Watts L. Caloric restriction increases ketone bodies metabolism and preserves blood flow in aging brain. Neurobiol Aging 2015; 36:2296-2303. [PMID: 25896951 PMCID: PMC4457572 DOI: 10.1016/j.neurobiolaging.2015.03.012] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 02/10/2015] [Accepted: 03/19/2015] [Indexed: 12/23/2022]
Abstract
Caloric restriction (CR) has been shown to increase the life span and health span of a broad range of species. However, CR effects on in vivo brain functions are far from explored. In this study, we used multimetric neuroimaging methods to characterize the CR-induced changes of brain metabolic and vascular functions in aging rats. We found that old rats (24 months of age) with CR diet had reduced glucose uptake and lactate concentration, but increased ketone bodies level, compared with the age-matched and young (5 months of age) controls. The shifted metabolism was associated with preserved vascular function: old CR rats also had maintained cerebral blood flow relative to the age-matched controls. When investigating the metabolites in mitochondrial tricarboxylic acid cycle, we found that citrate and α-ketoglutarate were preserved in the old CR rats. We suggest that CR is neuroprotective; ketone bodies, cerebral blood flow, and α-ketoglutarate may play important roles in preserving brain physiology in aging.
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Affiliation(s)
- Ai-Ling Lin
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA; Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA.
| | - Wei Zhang
- Research Imaging Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Xiaoli Gao
- Institutional Mass Spectrometry Laboratory, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA; Department of Biochemistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Lora Watts
- Research Imaging Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA; Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
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12
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Lin AL, Rothman DL. What have novel imaging techniques revealed about metabolism in the aging brain? FUTURE NEUROLOGY 2014; 9:341-354. [PMID: 25214817 DOI: 10.2217/fnl.14.13] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Brain metabolism declines with age and do so in an accelerated manner in neurodegenerative disorders. Noninvasive neuroimaging techniques have played an important role to identify the metabolic biomarkers in aging brain. Particularly, PET with fluorine-18 (18F)-labeled 2-fluoro-2-deoxy-d-glucose tracer and proton magnetic resonance spectroscopy (MRS) have been widely used to monitor changes in brain metabolism over time, identify the risk for Alzheimer's disease (AD) and predict the conversion from mild cognitive impairment to AD. Novel techniques, including PET carbon-11 Pittsburgh compound B, carbon-13 and phosphorus-31 MRS, have also been introduced to determine Aβ plaques deposition, mitochondrial functions and brain bioenergetics in aging brain and neurodegenerative disorders. Here, we introduce the basic principle of the imaging techniques, review the findings from 2-fluoro-2-deoxy-d-glucose-PET, Pittsburgh compound B PET, proton, carbon-13 and phosphorus-31 MRS on changes in metabolism in normal aging brain, mild cognitive impairment and AD, and discuss the potential of neuroimaging to identify effective interventions and treatment efficacy for neurodegenerative disorders.
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Affiliation(s)
- Ai-Ling Lin
- Sanders-Brown Center on Aging, Department of Pharmacology & Nutritional Sciences, University of Kentucky, Lexington, KY, USA
| | - Douglas L Rothman
- Magnetic Resonance Research Center, Diagnostic Radiology & Biomedical Engineering, Yale University, New Haven, CT, USA
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Moderate hyperventilation during intravenous anesthesia increases net cerebral lactate efflux. Anesthesiology 2014; 120:335-42. [PMID: 24008921 DOI: 10.1097/aln.0b013e3182a8eb09] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Hyperventilation is known to decrease cerebral blood flow (CBF) and to impair cerebral metabolism, but the threshold in patients undergoing intravenous anesthesia is unknown. The authors hypothesized that reduced CBF associated with moderate hyperventilation might impair cerebral aerobic metabolism in patients undergoing intravenous anesthesia. METHODS Thirty male patients scheduled for coronary surgery were included in a prospective, controlled crossover trial. Measurements were performed under fentanyl-midazolam anesthesia in a randomized sequence aiming at partial pressures of carbon dioxide of 30 and 50 mmHg. Endpoints were CBF, blood flow velocity in the middle cerebral artery, and cerebral metabolic rates for oxygen, glucose, and lactate. Global CBF was measured using a modified Kety-Schmidt technique with argon as inert gas tracer. CBF velocity of the middle cerebral artery was recorded by transcranial Doppler sonography. Data were presented as mean (SD). Two-sided paired t tests and one-way ANOVA for repeated measures were used for statistical analysis. RESULTS Moderate hyperventilation significantly decreased CBF by 60%, blood flow velocity by 41%, cerebral oxygen delivery by 58%, and partial pressure of oxygen of the jugular venous bulb by 45%. Cerebral metabolic rates for oxygen and glucose remained unchanged; however, net cerebral lactate efflux significantly increased from -0.38 (2.18) to -2.41(2.43) µmol min 100 g. CONCLUSIONS Moderate hyperventilation, when compared with moderate hypoventilation, in patients with cardiovascular disease undergoing intravenous anesthesia increased net cerebral lactate efflux and markedly reduced CBF and partial pressure of oxygen of the jugular venous bulb, suggesting partial impairment of cerebral aerobic metabolism at clinically relevant levels of hypocapnia.
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Nomura S, Inoue T, Ishihara H, Koizumi H, Suehiro E, Oka F, Suzuki M. Reliability of laser speckle flow imaging for intraoperative monitoring of cerebral blood flow during cerebrovascular surgery: comparison with cerebral blood flow measurement by single photon emission computed tomography. World Neurosurg 2013; 82:e753-7. [PMID: 24047822 DOI: 10.1016/j.wneu.2013.09.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 08/11/2013] [Accepted: 09/07/2013] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To determine the clinical utility of laser speckle flow imaging (LSFI) and its comparability to (123)I-iodoamphetamine single photon emission computed tomography (IMP-SPECT), we used LSFI to monitor cerebral blood flow (CBF) during extracranial-intracranial (EC-IC) bypass surgery. METHODS Intraoperative intensity of CBF (iCBF) by LSFI and preoperative and postoperative CBF by IMP-SPECT were measured in 3 patients with internal carotid artery (ICA) aneurysms who were undergoing ICA trapping surgery and in 16 patients with major cerebral artery occlusion who were undergoing EC-IC bypass surgery. RESULTS The decrease in iCBF (16.9% ± 2.3%) with ICA interruption was equivalent to the decrease in CBF during the preoperative balloon test occlusion, as measured by IMP-SPECT (12.2% ± 4.4%). Whether preserved iCBF in LSFI promised postoperative intact CBF was not determined, as no patient showed ischemic tolerance by ICA occlusion. The increase in iCBF resulting from EC-IC bypass correlated moderately with the increase in postoperative CBF as measured by IMP-SPECT. However, the increase in iCBF was too small to be recognized intraoperatively by visual inspection. CONCLUSIONS Although LSFI clearly demonstrated a decrease in CBF, the information is taken only from the surface of the brain. Combined use of LFSI with an electrophysiologic examination is required for intraoperative diagnosis of ischemia. LSFI was not sensitive enough to detect increased CBF by superficial temporal artery-to-middle cerebral artery anastomosis, because CBF changes are minimized during anesthesia, probably owing to low metabolic activity.
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Affiliation(s)
- Sadahiro Nomura
- Department of Neurosurgery, Yamaguchi University School of Medicine, Ube, Yamaguchi, Japan.
| | - Takao Inoue
- Department of Neurosurgery, Yamaguchi University School of Medicine, Ube, Yamaguchi, Japan
| | - Hideyuki Ishihara
- Department of Neurosurgery, Yamaguchi University School of Medicine, Ube, Yamaguchi, Japan
| | - Hiroyasu Koizumi
- Department of Neurosurgery, Yamaguchi University School of Medicine, Ube, Yamaguchi, Japan
| | - Eiichi Suehiro
- Department of Neurosurgery, Yamaguchi University School of Medicine, Ube, Yamaguchi, Japan
| | - Fumiaki Oka
- Department of Neurosurgery, Yamaguchi University School of Medicine, Ube, Yamaguchi, Japan
| | - Michiyasu Suzuki
- Department of Neurosurgery, Yamaguchi University School of Medicine, Ube, Yamaguchi, Japan
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15
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Methylene blue as a cerebral metabolic and hemodynamic enhancer. PLoS One 2012; 7:e46585. [PMID: 23056355 PMCID: PMC3467226 DOI: 10.1371/journal.pone.0046585] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Accepted: 09/03/2012] [Indexed: 12/04/2022] Open
Abstract
By restoring mitochondrial function, methylene blue (MB) is an effective neuroprotectant in many neurological disorders (e.g., Parkinson’s and Alzheimer’s diseases). MB has also been proposed as a brain metabolic enhancer because of its action on mitochondrial cytochrome c oxidase. We used in vitro and in vivo approaches to determine how MB affects brain metabolism and hemodynamics. For in vitro, we evaluated the effect of MB on brain mitochondrial function, oxygen consumption, and glucose uptake. For in vivo, we applied neuroimaging and intravenous measurements to determine MB’s effect on glucose uptake, cerebral blood flow (CBF), and cerebral metabolic rate of oxygen (CMRO2) under normoxic and hypoxic conditions in rats. MB significantly increases mitochondrial complex I–III activity in isolated mitochondria and enhances oxygen consumption and glucose uptake in HT-22 cells. Using positron emission tomography and magnetic resonance imaging (MRI), we observed significant increases in brain glucose uptake, CBF, and CMRO2 under both normoxic and hypoxic conditions. Further, MRI revealed that MB dramatically increased CBF in the hippocampus and in the cingulate, motor, and frontoparietal cortices, areas of the brain affected by Alzheimer’s and Parkinson’s diseases. Our results suggest that MB can enhance brain metabolism and hemodynamics, and multimetric neuroimaging systems offer a noninvasive, nondestructive way to evaluate treatment efficacy.
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16
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Prvulovic D, Bokde ALW, Faltraco F, Hampel H. Functional magnetic resonance imaging as a dynamic candidate biomarker for Alzheimer's disease. Prog Neurobiol 2011; 95:557-69. [PMID: 21722703 DOI: 10.1016/j.pneurobio.2011.05.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Revised: 05/24/2011] [Accepted: 05/27/2011] [Indexed: 11/18/2022]
Abstract
During the last two decades, imaging of neural activation has become an invaluable tool for assessing the functional organization of the human brain in vivo. Due to its widespread application in neuroscience, functional neuroimaging has raised the interest of clinical researchers in its possible use as a diagnostic biomarker. A hallmark feature of many neurodegenerative diseases is their chronic non-linear dynamic and highly complex preclinical course. Neurodegenerative diseases unfold over years to decades through clinically silent and asymptomatic stages of early adaptive, compensatory to pathophysiological (i.e. actively neurodegenerative) and decompensatory mechanisms in the brain - phases that are increasingly being considered as critical for primary and secondary preventive and therapeutic measures. Emerging evidence supports the concept of a potentially fully reversible functional phase that may precede the onset of micro- and macrostructural and cognitive decline, a potentially late-stage "neurodegenerative" phase of a primary neurodegenerative disorder. Alzheimer's disease serves as an ideal model to test this hypothesis supported by the neural network model of the healthy and diseased brain. Being highly dynamic in nature, brain activation and neuronal network functional connectivity represent not only candidate diagnostic but also candidate surrogate markers for interventional trials. Potential caveats of functional imaging are critically reviewed with focus on confound variables such as altered neurovascular coupling as well as parameters related to task- and study design.
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Affiliation(s)
- David Prvulovic
- Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, Goethe-University of Frankfurt, Frankfurt, Germany.
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Gur AY, Gücüyener D, Korczyn AD, Uzüner N, Gilutz Y, Ozdemir G, Bornstein NM. Cerebral vasomotor reactivity and dementia after ischemic stroke. Acta Neurol Scand 2010; 122:383-8. [PMID: 20085557 DOI: 10.1111/j.1600-0404.2010.01323.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVES Cerebral hemodynamic features of patients with post-stroke dementia (PSD) are still obscure. We compared cerebral vasomotor reactivity (VMR) assessed in the acute phase of ischemic stroke (IS) in patients with and without PSD. VMR was also assessed and compared in demented and non-demented patients in the late phase of IS. MATERIALS AND METHODS VMR was assessed by transcranial Doppler and the Diamox test (1 g acetazolamide i.v.). PSD was confirmed by the National Institute of Neurological Disorders and Stroke and the Association Internationale pour la Recherche et I'Enseignement en Neurosciences (NINDS-AIREN) and the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria. VMR% values were compared to verify correlation with dementia. RESULTS Thirty patients with acute IS (AIS) were studied and followed for 3-6 months. An additional group of 37 patients was studied in the late post-stroke period (PIS). VMR% values in the AIS groups with and without PSD were similar (25.3 ± 20.3% and 36.5 ± 22.4%, respectively, NS). The mean VMR% in the PIS groups with and without PSD were similar (32.3 ± 19.5% and 41.2 ± 24.8%, respectively, NS). CONCLUSIONS VMR cannot predict the development of dementia after AIS and cannot identify patients with dementia in the late phase of stroke.
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Affiliation(s)
- Alexander Y Gur
- Stroke Unit, Department of Neurology, Tel Aviv Sourasky Medical Center and The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
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Autoregulation of cerebral blood flow to changes in arterial pressure in mild Alzheimer's disease. J Cereb Blood Flow Metab 2010; 30:1883-9. [PMID: 20736966 PMCID: PMC2972357 DOI: 10.1038/jcbfm.2010.135] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Studies in transgenic mice overexpressing amyloid precursor protein (APP) demonstrate impaired autoregulation of cerebral blood flow (CBF) to changes in arterial pressure and suggest that cerebrovascular dysfunction may be critically important in the development of pathological Alzheimer's disease (AD). Given the relevance of such a finding for guiding hypertension treatment in the elderly, we assessed autoregulation in individuals with AD. Twenty persons aged 75±6 years with very mild or mild symptomatic AD (Clinical Dementia Rating 0.5 or 1.0) underwent (15)O-positron emission tomography (PET) CBF measurements before and after mean arterial pressure (MAP) was lowered from 107±13 to 92±9 mm Hg with intravenous nicardipine; (11)C-PIB-PET imaging and magnetic resonance imaging (MRI) were also obtained. There were no significant differences in mean CBF before and after MAP reduction in the bilateral hemispheres (-0.9±5.2 mL per 100 g per minute, P=0.4, 95% confidence interval (CI)=-3.4 to 1.5), cortical borderzones (-1.9±5.0 mL per 100 g per minute, P=0.10, 95% CI=-4.3 to 0.4), regions of T2W-MRI-defined leukoaraiosis (-0.3±4.4 mL per 100 g per minute, P=0.85, 95% CI=-3.3 to 3.9), or regions of peak (11)C-PIB uptake (-2.5±7.7 mL per 100 g per minute, P=0.30, 95% CI=-7.7 to 2.7). The absence of significant change in CBF with a 10 to 15 mm Hg reduction in MAP within the normal autoregulatory range demonstrates that there is neither a generalized nor local defect of autoregulation in AD.
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Claassen JAHR, Diaz-Arrastia R, Martin-Cook K, Levine BD, Zhang R. Altered cerebral hemodynamics in early Alzheimer disease: a pilot study using transcranial Doppler. J Alzheimers Dis 2009; 17:621-9. [PMID: 19433892 DOI: 10.3233/jad-2009-1079] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Cerebrovascular disease may contribute to the development and progression of Alzheimer's disease (AD). This study investigated whether impairments in cerebral hemodynamics can be detected in early-stage AD. Nine patients with mild AD and eight cognitively normal controls matched for age underwent brain magnetic resonance imaging and neuropsychological evaluation, followed by assessment of steady-state cerebral blood flow velocity (CBFV, transcranial Doppler), blood pressure (BP, Finapres), and cerebrovascular resistance index (BP/CBFV). Cerebral hemodynamics were quantified using spectral and transfer function analysis of BP and CBFV in rest, during standing up after squat, and during repeated squat-stand maneuvers. Compared to controls, AD patients had lower CBFV and higher cerebrovascular resistance index, unexplained by brain atrophy. Low-frequency variability of BP was enhanced, suggesting impaired arterial baroreflex function. However, CBFV variability was reduced despite enhanced BP variability, and dynamic cerebral autoregulation was not impaired. In conclusion, despite a distinct pattern of altered cerebral hemodynamics, AD patients may have normal autoregulation. However, the challenges for autoregulation in AD are higher, as our data show enhanced BP fluctuations. Increased cerebral vasoconstriction or reduced vasomotion also may attenuate CBFV variability.
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Affiliation(s)
- Jurgen A H R Claassen
- Department of Geriatric Medicine, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
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Kitagawa K, Oku N, Kimura Y, Yagita Y, Sakaguchi M, Hatazawa J, Sakoda S. Relationship between cerebral blood flow and later cognitive decline in hypertensive patients with cerebral small vessel disease. Hypertens Res 2009; 32:816-20. [DOI: 10.1038/hr.2009.100] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
Dementia represents a heterogeneous term that has evolved to describe the behavioral syndromes associated with a variety of clinical and neuropathological changes during continuing degenerative disease of the brain. As such, there lacks a clear consensus regarding the neuropsychological and other constituent characteristics associated with various cerebrovascular changes in this disease process. But increasing this knowledge has given more insights into memory deterioration in patients suffering from Alzheimer's disease and other subtypes of dementia. The author reviews current knowledge of the physiological coupling between cerebral blood flow and metabolism in the light of state-of-the-art-imaging methods and its changes in dementia with special reference to Alzheimer's disease. Different imaging techniques are discussed with respect to their visualizing effect of biochemical, cellular, and/or structural changes in dementia. The pathophysiology of dementia in advanced age is becoming increasingly understood by revealing the underlying basis of neuropsychological changes with current imaging techniques, genetic and pathological features, which suggests that alterations of (neuro) vascular regulatory mechanisms may lead to brain dysfunction and disease. The current view is that cerebrovascular deregulation is seen as a contributor to cerebrovascular pathologies, such as stroke, but also to neurodegenerative conditions, such as Alzheimer's disease. The better understanding of these (patho) physiological mechanisms may open an approach to new interventional strategies in dementia to enhance neurovascular repair and to protect neurovascular coupling.
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Boles Ponto LL, Magnotta VA, Moser DJ, Duff KM, Schultz SK. Global cerebral blood flow in relation to cognitive performance and reserve in subjects with mild memory deficits. Mol Imaging Biol 2007; 8:363-72. [PMID: 17048070 DOI: 10.1007/s11307-006-0066-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE This study was undertaken to explore the mechanisms underlying cognitive reserve in subjects with mild memory deficits by using positron emission tomography (PET). METHODS Global cerebral blood flow (gCBF) and cerebrovascular reserve (CVR) measurements were performed in 15 elders (5 men, 10 women, 62-84, 71.8 +/- 6.2 years) meeting criteria for mild cognitive impairment (MCI). PET consisted of quantitative [(15)O]water determinations of CBF, two at baseline and one postadministration of acetazolamide (ACZ). RESULTS Mean gCBF were 44.9 +/- 5.5 during counting, 44.5 +/- 6.7 for the memory task, and 60.2 +/- 4.8 ml/min/100 g for post-ACZ (CVR of 33.9 +/- 13.2%). Task-related gCBF change was significantly related to memory score, performance on the Trail Making Test B (Trails-B), premorbid IQ, and education, and differed significantly between the learning-based groups. CONCLUSIONS Cognitive reserve appears analogous to cardiac reserve. The ability to alter gCBF paralleled performance on general cognitive measures, was enhanced in higher levels of cognitive reserve, and was impaired in individuals who no longer appear to benefit from repeated exposure to testing.
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Affiliation(s)
- Laura L Boles Ponto
- Positron Emission Tomography Imaging Center, Department of Radiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa, IA 52242, USA.
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Bateman GA, Levi CR, Schofield P, Wang Y, Lovett EC. Quantitative measurement of cerebral haemodynamics in early vascular dementia and Alzheimer's disease. J Clin Neurosci 2006; 13:563-8. [PMID: 16540327 DOI: 10.1016/j.jocn.2005.04.017] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2005] [Accepted: 04/07/2005] [Indexed: 11/19/2022]
Abstract
Alzheimer's disease (AD) and vascular dementia (VaD) both share significant vascular risk factors. The present study measures the haemodynamics of these diseases in absolute rather than relative terms. Twenty-four patients were classified as either early AD or VaD and were compared with 12 non-cognitively impaired subjects. Magnetic resonance imaging flow quantification was used to measure arterial inflow and arterial pulse volume. Mean vascular resistance and compliance were calculated. In AD, the arterial inflow was lower by 18%, resistance was higher by 23% and compliance of the arterial tree was lower by 20% compared with normal (p=0.01, 0.02 and 0.05, respectively). In VaD, the arterial pulse volume was higher by 24% and compliance was higher by 35% compared with normal (p=0.05 for both). Early VaD is characterized by normal blood flow, but increased pulsation. Reduced blood flow and an incompliant arterial tree characterize early AD.
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Affiliation(s)
- Grant A Bateman
- Department of Medical Imaging, John Hunter Hospital, Locked Bag 1, Newcastle Region Mail Center, New South Wales 2310, Australia.
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Boles Ponto LL, Schultz SK, Leonard Watkins G, Hichwa RD. Technical issues in the determination of cerebrovascular reserve in elderly subjects using 15O-water PET imaging. Neuroimage 2004; 21:201-10. [PMID: 14741657 DOI: 10.1016/j.neuroimage.2003.09.044] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
The accurate determination of cerebrovascular reserve (CVR), especially in elderly subjects, entails several technical issues. From a review of the literature, the optimal technique employs quantitative 15O-water PET imaging determinations of cerebral blood flow (CBF) and acetazolamide (ACZ) (1 g iv with measurements at 10- to 20-min post-administration) as the vasodilating agent. CBF and CVR measurements were made using this methodology on 12 elderly subjects (3 males, 9 females, 66-84 years of age) meeting criteria for mild cognitive impairment (MCI) without other significant medical problems. Applying this quantitative technique, the cognitive and emotional status of the subject during the imaging procedure influenced the magnitude of the measurements. The semiquantitative measures resulted in even more pronounced subject state influences. The conditions under which CBF or CVR measurements are made should be controlled and reported. If semiquantitative techniques (e.g., single-photon emission-computed tomography [SPECT] imaging) must be employed for the determination of CVR, the validity of any measurement is dependent on the careful control of the general physiological status (e.g., heart rate, blood pressure, level of anxiety) of the patient.
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Affiliation(s)
- Laura L Boles Ponto
- Positron Emission Tomography Imaging Center, Department of Radiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, USA.
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Nagata K, Sato M, Satoh Y, Watahiki Y, Kondoh Y, Sugawara M, Box G, Wright D, Leung S, Yuya H, Shimosegawa E. Hemodynamic aspects of Alzheimer's disease. Ann N Y Acad Sci 2002; 977:391-402. [PMID: 12480778 DOI: 10.1111/j.1749-6632.2002.tb04843.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Neuroradiological functional imaging techniques demonstrate the patterns of hypoperfusion and hypometabolism that are thought to be useful in the differential diagnosis of Alzheimer's disease (AD) from other dementing disorders. Besides the distribution patterns of perfusion or energy metabolism, vascular transit time (VTT), vascular reactivity (VR), and oxygen extraction fraction (OEF), which can be measured with positron emission tomography (PET), provide hemodynamic aspects of brain pathophysiology. In order to evaluate the hemodynamic features of AD, PET studies were carried out in 20 patients with probable AD and 20 patients with vascular dementia (VaD). The PET findings were not included in their diagnostic process of AD. Using oxygen-15-labeled compounds, cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO(2)), OEF, cerebral blood volume, and VTT were measured quantitatively during resting state. To evaluate VR, CBF was also measured during CO(2) inhalation. There was a significant increase in OEF in and around the parietotemporal cortices, but both VTT and VR were well preserved in patients with AD. By contrast, VR was markedly depressed and VTT was mildly prolonged in patients with VaD. Thus, from the hemodynamic point of view, the preservation of vascular reserve may be a distinct difference between AD and VaD. Furthermore, this indicates a hemodynamic integrity of the vasculature in the level of arterioles in AD.
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Affiliation(s)
- Ken Nagata
- Department of Neurology, Research Institute for Brain and Blood Vessels, 6-10 Senshu-Kubota-Machi, Akita 010-0874, Japan.
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26
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Niwa K, Kazama K, Younkin L, Younkin SG, Carlson GA, Iadecola C. Cerebrovascular autoregulation is profoundly impaired in mice overexpressing amyloid precursor protein. Am J Physiol Heart Circ Physiol 2002; 283:H315-23. [PMID: 12063304 DOI: 10.1152/ajpheart.00022.2002] [Citation(s) in RCA: 213] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The amyloid-beta (A beta) peptide, which is derived from the amyloid precursor protein (APP), is involved in the pathogenesis of Alzheimer's dementia and impairs endothelium-dependent vasodilation in cerebral vessels. We investigated whether cerebrovascular autoregulation, i.e., the ability of the cerebral circulation to maintain flow in the face of changes in mean arterial pressure (MAP), is impaired in transgenic mice that overexpress APP and A beta. Neocortical cerebral blood flow (CBF) was monitored by laser-Doppler flowmetry in anesthetized APP(+) and APP(-) mice. MAP was elevated by intravenous infusion of phenylephrine and reduced by controlled exsanguination. In APP(-) mice, autoregulation was preserved. However, in APP(+) mice, autoregulation was markedly disrupted. The magnitude of the disruption was linearly related to brain A beta concentration. The failure of autoregulation was paralleled by impairment of the CBF response to endothelium-dependent vasodilators. Thus A beta disrupts a critical homeostatic mechanism of the cerebral circulation and renders CBF highly dependent on MAP. The resulting alterations in cerebral perfusion may play a role in the brain dysfunction and periventricular white-matter changes associated with Alzheimer's dementia.
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Affiliation(s)
- Kiyoshi Niwa
- Department of Neurology, University of Minnesota, Minneapolis, Minnesota 55455, USA
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27
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Abstract
BACKGROUND The main stumbling block in the clinical management and in the search for a cure of Alzheimer disease (AD) is that the cause of this disorder has remained uncertain until now. SUMMARY OF REVIEW Evidence that sporadic (nongenetic) AD is primarily a vascular rather than a neurodegenerative disorder is reviewed. This conclusion is based on the following evidence: (1) epidemiological studies showing that practically all risk factors for AD reported thus far have a vascular component that reduces cerebral perfusion; (2) risk factor association between AD and vascular dementia (VaD); (3) improvement of cerebral perfusion obtained from most pharmacotherapy used to reduce the symptoms or progression of AD; (4) detection of regional cerebral hypoperfusion with the use of neuroimaging techniques to preclinically identify AD candidates; (5) presence of regional brain microvascular abnormalities before cognitive and neurodegenerative changes; (6) common overlap of clinical AD and VaD cognitive symptoms; (7) similarity of cerebrovascular lesions present in most AD and VaD patients; (8) presence of cerebral hypoperfusion preceding hypometabolism, cognitive decline, and neurodegeneration in AD; and (9) confirmation of the heterogeneous and multifactorial nature of AD, likely resulting from the diverse presence of vascular risk factors or indicators of vascular disease. CONCLUSIONS Since the value of scientific evidence generally revolves around probability and chance, it is concluded that the data presented here pose a powerful argument in support of the proposal that AD should be classified as a vascular disorder. According to elementary statistics, the probability or chance that all these findings are due to an indirect pathological effect or to coincidental circumstances related to the disease process of AD seems highly unlikely. The collective data presented in this review strongly support the concept that sporadic AD is a vascular disorder. It is recommended that current clinical management of patients, treatment targets, research designs, and disease prevention efforts need to be critically reassessed and placed in perspective in light of these important findings.
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Affiliation(s)
- J C de la Torre
- Department of Neuropathology, University of California at San Diego, CA 92026, USA.
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28
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de la Torre JC. Impaired cerebromicrovascular perfusion. Summary of evidence in support of its causality in Alzheimer's disease. Ann N Y Acad Sci 2001; 924:136-52. [PMID: 11193790 DOI: 10.1111/j.1749-6632.2000.tb05572.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
After nearly a century of inquiry, the cause of Alzheimer's disease (AD) remains to be found. In this review, basic and clinical evidence is presented that assembles and hypothetically explains most of the key pathologic events associated with the development of AD. These pathologic events are triggered in AD by impaired cerebral perfusion originating in the microvasculature that affects the optimal delivery of glucose and oxygen and results in an energy metabolic breakdown of brain cell biosynthetic and synaptic pathways. We propose that two factors must be present before cognitive dysfunction and neurodegeneration is expressed in the AD brain: (1) advanced aging, (2) presence of a condition that lowers cerebral perfusion, such as a vascular risk factor. The first factor introduces a normal but potentially menacing process that lowers cerebral blood flow in proportion to increased aging, while the second factor adds a crucial burden that further lowers brain perfusion and places vulnerable neurons in a state of metabolic compromise leading to a death pathway. These two factors will lead to a critically attained threshold of cerebral hypoperfusion (CATCH). CATCH is a self-sustaining and progressive circulatory insufficiency that will destabilize neurons, synapses, neurotransmission, and cognitive function, creating in its wake a neurodegenerative process characterized by the formation of senile plaques, neurofibrillary tangles, amyloid angiopathy, and, in some cases, Lewy bodies. Since any of a considerable number of vessel-related conditions must be present in the aging individual for cognition to be affected, CATCH supports the heterogeneic disease profile assumed to be characteristic of the AD syndrome. A brief discussion of target therapy based on the proposed pathogenesis of AD is also reviewed.
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Affiliation(s)
- J C de la Torre
- Department of Neuroscience, University of California, San Diego, La Jolla, California 92093, USA.
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29
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Alsop DC, Detre JA, Grossman M. Assessment of cerebral blood flow in Alzheimer's disease by spin-labeled magnetic resonance imaging. Ann Neurol 2001. [DOI: 10.1002/1531-8249(200001)47:1<93::aid-ana15>3.0.co;2-8] [Citation(s) in RCA: 297] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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30
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Gsell W, De Sadeleer C, Marchalant Y, MacKenzie ET, Schumann P, Dauphin F. The use of cerebral blood flow as an index of neuronal activity in functional neuroimaging: experimental and pathophysiological considerations. J Chem Neuroanat 2000; 20:215-24. [PMID: 11207420 DOI: 10.1016/s0891-0618(00)00095-8] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Over recent years, activation studies that have been undertaken using brain imaging techniques, such as functional magnetic resonance imaging, positron emission tomography or near infrared spectroscopy, have greatly improved our knowledge of the functional anatomy of the brain. Nevertheless, activation studies do not directly quantify the variations of synaptic transmission (neuronal activity) but detect it indirectly either through the visualisation of changes in cerebral blood flow, oxidative or glycolytic metabolism (for positron emission tomography), or through the measurement of a global index that is dependent on both cerebral blood flow and oxidative metabolism (for functional magnetic resonance imaging and near infrared spectroscopy). Such approaches are based on the concept of a tight parallelism--termed coupling--between variations in neuronal activity, metabolism and cerebral blood flow. However, several "uncoupled" situations between these parameters have been reported over the last decade through experimental, pharmacological and pathophysiological studies. The aim of this review is to focus on these data that have to be taken into account for the interpretation of the results obtained in activation paradigms.
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Affiliation(s)
- W Gsell
- Université de Caen, UMR 6551 CNRS, Centre Cyceron, IFR47, Caen, France
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31
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de la Torre JC, Stefano GB. Evidence that Alzheimer's disease is a microvascular disorder: the role of constitutive nitric oxide. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 2000; 34:119-36. [PMID: 11113503 DOI: 10.1016/s0165-0173(00)00043-6] [Citation(s) in RCA: 208] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Evidence is fast accumulating which indicates that Alzheimer's disease is a vascular disorder with neurodegenerative consequences rather than a neurodegenerative disorder with vascular consequences. It is proposed that two factors need to be present for AD to develop: (1) advanced ageing, (2) presence of a condition that lowers cerebral perfusion, such as a vascular-risk factor. The first factor introduces a normal but potentially insidious process that lowers cerebral blood flow in inverse relation to increased ageing; the second factor adds a crucial burden which further lowers brain perfusion and places vulnerable neurons in a state of high energy compromise leading to a cascade of neuronal metabolic turmoil. Convergence of the two factors above will culminate in a critically attained threshold of cerebral hypoperfusion (CATCH). CATCH is a hemodynamic microcirculatory insufficiency that will destabilize neurons, synapses, neurotransmission and cognitive function, creating in its wake a neurodegenerative state characterized by the formation of senile plaques, neurofibrillary tangles, amyloid angiopathy and in some cases, Lewy bodies. Since any of a considerable number of vascular-related conditions must be present in the ageing individual for cognition to be disturbed, CATCH identifies an important aspect of the heterogeneic disease profile assumed to be present in the AD syndrome. It is proposed that CATCH initiates AD by distorting regional brain capillary structure involving endothelial cell shape changes and impairment of nitric oxide (NO) release which affect signaling between the immune, cardiovascular and nervous systems. Evidence is presented that in many tissues there is a basal level of NO being produced and that the actions of several signaling molecules may initiate increases in basal NO levels. Moreover, these temporary increases in basal NO levels exert inhibitory cellular actions, via cellular conformational changes. Findings indicate that (a) constitutive NO is responsible for a basal or 'tonal' level of NO; (b) this NO keeps particular types of cells in a state of inhibition and (c) activation of these cells occurs through disinhibition. Consequently, tissues not maintaining a basal NO level are more prone to excitatory, immune, vascular and neural influences. Under such circumstances, these tissues cannot be down-regulated to normal basal levels, thus prolonging their excitatory state. Thus, the clinical convergence of advanced ageing in the presence of a chronic, pre-morbid vascular risk factor, can, in time, contribute to an endotheliopathy involving basal NO deficit, to the degree where regional metabolic dysfunction leads to cognitive meltdown and to progressive neurodegeneration characteristic of Alzheimer's disease.
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Affiliation(s)
- J C de la Torre
- Department of Pathology, University of California, San Diego, 1363 Shinly, Suite 100, Escondido, CA 92026, USA.
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32
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de la Torre JC. Cerebral hypoperfusion, capillary degeneration, and development of Alzheimer disease. Alzheimer Dis Assoc Disord 2000; 14 Suppl 1:S72-81. [PMID: 10850734 DOI: 10.1097/00002093-200000001-00012] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Considerable clinical and experimental data have shown that cerebral perfusion is progressively decreased during increased aging and that this decrease in brain blood flow is significantly greater in Alzheimer disease (AD). The authors propose that advanced aging with a comorbid condition, such as a vascular risk factor, which further decreases cerebral perfusion, promotes a critically attained threshold of cerebral hypoperfusion (CATCH). With time, CATCH induces brain capillary degeneration and suboptimal delivery of energy substrates to neuronal tissue. Because glucose is the main fuel of brain cells, its impaired delivery, with the deficient delivery of oxygen, compromises neuronal stability because the supply for aerobic glycolysis fails to meet brain tissue demand. The outcome of CATCH is a metabolic cascade that involves, among other things, mitochondrial dysfunction, oxidative stress, decreased adenosine triphosphate production, abnormal protein synthesis, cell ionic pump deficiency, signal transduction defects, and neurotransmission failure. These events contribute to the progressive cognitive decline characteristic of patients with AD, as well as regional anatomic pathology, consisting of synaptic loss, senile plaques, neurofibrillary tangles, tissue atrophy, and neurodegeneration. CATCH identifies the clinical heterogeneic pattern that characterizes AD because it provides compelling evidence that any of a multitude of different etiopathophysiologic vascular risk factors, in the presence of advanced aging, can lead to AD. The evidence in support of CATCH as the pathogenic trigger of AD is crystallized in this review.
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Affiliation(s)
- J C de la Torre
- Department of Neuroscience, University of California, San Diego, La Jolla 92093, USA
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33
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Nagata K, Maruya H, Yuya H, Terashi H, Mito Y, Kato H, Sato M, Satoh Y, Watahiki Y, Hirata Y, Yokoyama E, Hatazawa J. Can PET data differentiate Alzheimer's disease from vascular dementia? Ann N Y Acad Sci 2000; 903:252-61. [PMID: 10818514 DOI: 10.1111/j.1749-6632.2000.tb06375.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The present study endeavored to differentiate Alzheimer's disease (AD) from vascular dementia (VaD) by comparing the metabolic and hemodynamic parameters. Positron emission tomographic (PET) studies were carried out in 13 patients with probable AD and 20 patients with VaD. PET findings were not included in the diagnostic criteria of AD or VaD. Using oxygen-15 labeled compounds, cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO2), oxygen extraction fraction (OEF), cerebral blood volume, and vascular transit time (VTT) were measured quantitatively during the resting state. To evaluate vascular reactivity (VR), CBF was also measured during 7% CO2 inhalation. Regional CBF from the parietal cortex positively correlated with the neuropsychological scores in both AD and VaD groups. The typical parietotemporal pattern of hypoperfusion and hypometabolism was observed in the AD group, whereas the frontal lobe including the cingulate and superior frontal gyri were predominantly affected in the VaD group. The occipital cortex was preserved in both groups. A significant increase of the OEF was found in the parietotemporal areas in the AD group. No significant prolongation was seen with VTT. There was a marked difference in VR between the two groups: VR was depleted in the VaD group, whereas VR was normal in the AD group. The increased OEF with preserved vascular reserve seen in AD may implicate participation of a vascular factor in the pathogenesis of AD, possibly at the capillary level. Thus, PET provides important functional information in discriminating AD from VaD by comparing the patterns of hypoperfusion and/or hypometabolism, and in the understanding of the underlying hemodynamic pathophysiology.
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Affiliation(s)
- K Nagata
- Department of Neurology, Research Institute for Brain and Blood Vessels, Akita, Japan.
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34
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Abstract
Mounting evidence from in vitro and in vivo studies in transgenic mice overproducing beta-amyloid peptides (A beta) suggests that A beta can induce vasoconstriction and decrease cerebral blood flow. In this report, we describe the vasoactive properties of A beta, in particular the enhancement of endothelin-1-induced vasoconstriction and A beta's induction of a long-lasting vasoconstrictive event. Furthermore, we show that low doses (as low as 50 nM) of freshly solubilized A beta similar to those observed in the plasma of patients suffering from Alzheimer's disease are vasoactive. By using various inhibitors and activators of the phospholipase A2 (PLA2)/arachidonic acid (AA) cascade, we demonstrate that A beta vasoactivity is dependent on activation of this intracellular signaling pathway, resulting in stimulation of downstream cyclooxygenase-2 and 5-lipoxygenase, which mediate production of proinflammatory eicosanoids. Taken together, our data show that A beta directly activates an intracellular proinflammatory pathway, which is responsible for its vasoactive properties.
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Affiliation(s)
- D Paris
- Roskamp Institute, University of South Florida, Tampa 33613, USA
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35
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de la Monte SM, Sohn YK, Etienne D, Kraft J, Wands JR. Role of aberrant nitric oxide synthase-3 expression in cerebrovascular degeneration and vascular-mediated injury in Alzheimer's disease. Ann N Y Acad Sci 2000; 903:61-71. [PMID: 10818490 DOI: 10.1111/j.1749-6632.2000.tb06351.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nitric oxide (NO) is an important signaling molecule that is generated through the catalytic activity of nitric oxide synthase (NOS). In the brain, NO mediates neuronal survival, synaptic plasticity, vascular smooth muscle relaxation, and endothelial cell permeability. Previous studies demonstrated aberrant expression of the NOS-III gene in neurons and glial cells in brains with Alzheimer's disease (AD). Since NOS-III is also expressed in vascular cells, and cerebrovascular disease (CVD) frequently complicates the pathology of AD, we investigated the role of NOS-III in relation to CVD in AD. Vasculopathy in AD + CVD was characterized by thickening and hyalinization of the media of small and medium-size vessels, variable degrees of beta-amyloid (A beta) deposition, and increased apoptosis of vascular smooth muscle and endothelial cells, particularly involving white matter vessels. These abnormalities were correlated with reduced levels of NOS-III expression in cerebral vessels. Double-labeling studies demonstrated that the low levels of cerebrovascular NOS-III were associated with increased levels of the pro-apoptosis gene product, p53 in smooth muscle and endothelial cells, suggesting a role for altered NOS-III expression in AD-associated vascular degeneration. Constitutively reduced cerebrovascular NOS-III expression and NO production could also lead to cerebral hypoperfusion due to impaired vasodilation responses, and diminished capacity to remove respiratory waste products and toxins from the extracellular space due to reduced capillary permeability. The role for phosphodiesterases as modulators of NOS activity is discussed, as these molecules represent potential therapeutic targets given their cell type and cyclic nucleotide specificities of action.
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Affiliation(s)
- S M de la Monte
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston 02129, USA.
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36
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de la Torre JC. Critically attained threshold of cerebral hypoperfusion: can it cause Alzheimer's disease? Ann N Y Acad Sci 2000; 903:424-36. [PMID: 10818533 DOI: 10.1111/j.1749-6632.2000.tb06394.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
After nearly a century of inquiry, the cause of sporadic Alzheimer's disease (AD) remains to be found. On the subject of AD pathogenesis, recent basic and clinical evidence strongly argues in favor of the concept that AD is linked to brain circulatory pathology. This concept, when viewed from many different medical disciplines and from close pre-morbid similarities to vascular dementia, assembles and hypothetically explains most of the key pathologic events associated with the development of AD. These pathologic events are triggered in AD by impaired cerebral perfusion originating in the microvasculature which affects the optimal delivery of glucose and oxygen and results in an energy metabolic breakdown of brain cell biosynthetic and synaptic pathways. We propose that two factors converge to initiate cognitive dysfunction and neurodegeneration as expressed in AD brain: (1) advanced aging, and (2) the presence of a condition that lowers cerebral perfusion. The first factor introduces a normal but potentially deconstructing process that lowers cerebral blood flow in proportion to increased aging, whereas the second factor adds a crucial burden that further lowers brain perfusion to a critical threshold that triggers neuronal metabolic compromise. When age and a condition that lowers cerebral perfusion converge, critically attained threshold of cerebral hypoperfusion (CATCH) results. CATCH is a cyclical and progressive cerebrovascular insufficiency that will destabilize neurons, synapses, neurotransmission, and cognitive ability, eventually evolving into a neurodegenerative process characterized by the formation of senile plaques, neurofibrillary tangles, and amyloid angiopathy. The concept of impaired cerebral perfusion as the cause of this dementia also explains the heterogeneic profile observed in AD patients, because an extensive list of risk factors for AD are also reported to significantly diminish blood flow to the aging brain.
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Affiliation(s)
- J C de la Torre
- Department of Neurosciences, University of California, San Diego, La Jolla 92093, USA.
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37
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Johnson SC, Saykin AJ, Baxter LC, Flashman LA, Santulli RB, McAllister TW, Mamourian AC. The relationship between fMRI activation and cerebral atrophy: comparison of normal aging and alzheimer disease. Neuroimage 2000; 11:179-87. [PMID: 10694460 DOI: 10.1006/nimg.1999.0530] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Functional MRI has recently been used to examine activation associated with aging and dementia, yet little is known regarding the effect of cerebral atrophy on fMRI signal. The purpose of this study was to examine the relationship between measures of global and regionally specific atrophy and fMRI activation in normal aging and in Alzheimer disease (AD). Two groups of subjects were studied with echoplanar imaging and quantitative structural volumetry: healthy controls spanning a broad age and atrophy range (n = 16) and patients with mild AD (n = 8). Results from a semantic task previously found to activate left inferior frontal (LIFG) and left superior temporal (LSTG) gyri were analyzed. The correlations between clusters of activation in the LIFG and LSTG and measures of local atrophy in the LIFG and LSTG regions were evaluated. For control subjects, there was no significant correlation between activation and regional or total brain atrophy (for LIFG r = -0.03, NS; for LSTG r = 0.20, NS). In contrast, for AD patients, there was a significant positive correlation between atrophy and activation in LIFG (r = 0.70, P = 0.05) but not LSTG (r = 0.00, NS). These results suggest that activation of language regions and atrophy within those regions may be independent among healthy adults spanning a broad age and atrophy range. However, in AD, a relationship exists in the LIFG that may reflect compensatory recruitment of cortical units or disease-specific changes in the hemodynamic response.
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Affiliation(s)
- S C Johnson
- Department of Psychiatry, New Hampshire Hospital, Lebanon, New Hampshire, 03756, USA
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38
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Farkas E, De Vos RA, Jansen Steur EN, Luiten PG. Are Alzheimer's disease, hypertension, and cerebrocapillary damage related? Neurobiol Aging 2000; 21:235-43. [PMID: 10867208 DOI: 10.1016/s0197-4580(00)00122-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Alzheimer's disease (AD) patients are often subject to vascular dysfunction besides their specific CNS pathology, which warrants further examination of the interaction between vascular factors and the development of dementia. The association of decreased cerebral blood flow (CBF) or hypertension with AD has been a target of growing interest. Parallel with physiological changes, the cerebral capillaries in AD are also prone to degenerative processes. The microvascular abnormalities that are the result of such degeneration may be the morphological correlates of the vascular pathophysiology pointing to a compromised nutrient transport through the capillaries. Animal models have been developed to study the consequences of hypertension and reduced CBF. Spontaneously hypertensive rats are widely used in hypertension research whereas ligation of the carotid arteries has become a method to produce cerebral hypoperfusion. Based on these models, we propose a relationship between hypertension, cerebral hypoperfusion, cerebral capillary malformation and cognitive decline as it occurs in AD. We suggest that the above conditions are functionally related and can contribute to the progression of AD.
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Affiliation(s)
- E Farkas
- Department of Animal Physiology, Graduate School of Behavioral and Cognitive Neurosciences, University of Groningen, Groningen, The Netherlands.
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39
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Cada A, de la Torre JC, Gonzalez-Lima F. Chronic cerebrovascular ischemia in aged rats: effects on brain metabolic capacity and behavior. Neurobiol Aging 2000; 21:225-33. [PMID: 10867207 DOI: 10.1016/s0197-4580(00)00116-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The objective of this study was to model one of the risk factors for the development of late-onset Alzheimer's disease, decreased cerebral blood flow. Aging rats were tested for visuospatial behavioral deficits after permanent surgical occlusion of both carotid arteries. This was followed after 4 weeks by quantitative cytochrome oxidase histochemical mapping of metabolic capacity throughout the brain. The brain regions affected were related to observed deficits in spatial memory (CA1 and posterior parietal cortex), visually guided movements (superior colliculus and secondary visual cortex), motor coordination (red nucleus), and escape behavior (central gray). The results suggest that deficits in visuospatial learning are not exclusively the result of hippocampal dysfunction, but may be directly correlated with altered oxidative energy metabolism in other integrative visuomotor regions identified in this study. It was concluded that chronic cerebrovascular ischemia in this aged rat model produces neurometabolic and behavioral alterations that may be relevant for an increased risk for the development of Alzheimer's disease.
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Affiliation(s)
- A Cada
- Institute for Neuroscience and Department of Psychology, University of Texas at Austin, Mezes Hall 330, 78712, Austin, TX, USA
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40
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de la Monte SM, Lu BX, Sohn YK, Etienne D, Kraft J, Ganju N, Wands JR. Aberrant expression of nitric oxide synthase III in Alzheimer's disease: relevance to cerebral vasculopathy and neurodegeneration. Neurobiol Aging 2000; 21:309-19. [PMID: 10867216 DOI: 10.1016/s0197-4580(99)00108-6] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Alzheimer's disease (AD) has heterogeneous pathology, in part due to the large subset of cases (AD+CVD) with superimposed vascular lesions that are sufficient in number and distribution to accelerate the clinical course of dementia. Brains with AD+CVD have lower densities of neurofibrillary tangles and A beta-amyloid diffuse plaques, and increased numbers of cerebral vessels exhibiting p53-associated apoptosis relative to brains with uncomplicated AD. AD and AD+CVD both exhibit altered expression of the nitric oxide synthase 3 (NOS-III) gene; however, in AD+CVD, reduced NOS-III expression in cerebral vessels is associated with an increased frequency of vascular lesions, vascular smooth muscle cell apoptosis, and A beta-amyloid plaques. In contrast, experimental and spontaneous focal acute and subacute cerebral infarcts are associated with increased NOS-III expression in perifocal neurons, glial cells, cerebrovascular smooth muscle and endothelial cells, and diffuse A beta-amyloid plaque formation. This suggests that ischemic injury and oxidative stress can precipitate NOS-III-mediated cell loss and neurodegeneration. A role for aging-associated impaired mitochondrial function as a contributing factor in AD and CVD is suggested by the reduced levels of mitochondrial protein observed in AD and AD+CVD cortical neurons and vascular smooth muscle and endothelial cells. The aggregate findings suggest that cell loss and neurodegeneration may be mediated by somewhat distinct but overlapping mechanisms in AD and AD+CVD.
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Affiliation(s)
- S M de la Monte
- Rhode Island Hospital, Brown University School of Medicine, 55 Claverick Street, 4th floor, Providence, RI 02903, USA.
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41
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Nagata K, Kondoh Y, Atchison R, Sato M, Satoh Y, Watahiki Y, Hirata Y, Yokoyama E. Vascular and metabolic reserve in Alzheimer's disease. Neurobiol Aging 2000; 21:301-7. [PMID: 10867215 DOI: 10.1016/s0197-4580(00)00130-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Vascular and metabolic reserve were analyzed in probable Alzheimer's disease (AD) and vascular dementia (VaD). Cerebral blood flow (CBF), cerebral blood volume (CBV), cerebral metabolic rate of oxygen (CMRO(2)), and oxygen extraction fraction (OEF) were measured quantitatively with positron emission tomography (PET). Vascular reactivity (VR) was also calculated by comparing the CBF during 5% CO(2) inhalation with the CBF during normal breathing. Vascular transit time (VTT) that was calculated as a ratio of CBV/CBF and VR reflect vasodilating capacity of the small resistance vessels, whereas OEF designates metabolic (oxygen-extraction) reserve in threatening brain ischemia. Significant increase in OEF was seen in the parieto-temporal cortex and both VTT and VR were preserved in AD patients. By constrast, there was no significant increase in OEF whereas VTT was prolonged and VR was markedly depressed in VaD patients. The increase of OEF and preserved VTT and VR seen in AD patients indicate the possible participation of vascular factors in the pathogenesis of AD perhaps at the capillary level.
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Affiliation(s)
- K Nagata
- Department of Neurology, Research Institute for Brain and Blood Vessels, 6-10 Senshu-Kubota-Machi, 010-0874, Akita, Japan.
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