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Stone J, Mitrofanis J, Johnstone DM, Robinson SR. The Catastrophe of Intracerebral Hemorrhage Drives the Capillary-Hemorrhage Dementias, Including Alzheimer's Disease. J Alzheimers Dis 2024; 97:1069-1081. [PMID: 38217606 DOI: 10.3233/jad-231202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2024]
Abstract
This review advances an understanding of several dementias, based on four premises. One is that capillary hemorrhage is prominent in the pathogenesis of the dementias considered (dementia pugilistica, chronic traumatic encephalopathy, traumatic brain damage, Alzheimer's disease). The second premise is that hemorrhage introduces four neurotoxic factors into brain tissue: hypoxia of the tissue that has lost its blood supply, hemoglobin and its breakdown products, excitotoxic levels of glutamate, and opportunistic pathogens that can infect brain cells and induce a cytotoxic immune response. The third premise is that where organisms evolve molecules that are toxic to itself, like the neurotoxicity ascribed to hemoglobin, amyloid- (A), and glutamate, there must be some role for the molecule that gives the organism a selection advantage. The fourth is the known survival-advantage roles of hemoglobin (oxygen transport), of A (neurotrophic, synaptotrophic, detoxification of heme, protective against pathogens) and of glutamate (a major neurotransmitter). From these premises, we propose 1) that the brain has evolved a multi-factor response to intracerebral hemorrhage, which includes the expression of several protective molecules, including haptoglobin, hemopexin and A; and 2) that it is logical, given these premises, to posit that the four neurotoxic factors set out above, which are introduced into the brain by hemorrhage, drive the progression of the capillary-hemorrhage dementias. In this view, A expressed at the loci of neuronal death in these dementias functions not as a toxin but as a first responder, mitigating the toxicity of hemoglobin and the infection of the brain by opportunistic pathogens.
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Affiliation(s)
- Jonathan Stone
- Faculty of Medicine and Health, University of Sydney, Sydney, Australia
| | - John Mitrofanis
- Université Grenoble Alpes, Fonds de Dotation, Clinatec, Grenoble, France
- Institute of Ophthalmology, University College London, London, UK
| | - Daniel M Johnstone
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, Australia
- School of Medical Sciences, The University of Sydney, Sydney, Australia
| | - Stephen R Robinson
- School of Health and Biomedical Sciences, RMIT University, Bundoora, Australia
- Institute for Breathing and Sleep, Austin Health, Heidelberg, Australia
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Machado MF, Muela HCS, Costa-Hong VA, Panerai RB, Yassuda MS, Moraes NC, Memória CM, Bor-Seng-Shu E, Nitrini R, Bortolotto LA, Nogueira RDC. Measurement of resistance-area product by transcranial Doppler: An alternative tool for cognitive screening in hypertensive on drug treatment? Cereb Circ Cogn Behav 2023; 5:100191. [PMID: 38046105 PMCID: PMC10692755 DOI: 10.1016/j.cccb.2023.100191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 09/02/2023] [Accepted: 11/08/2023] [Indexed: 12/05/2023]
Abstract
Introduction Arterial hypertrophy and remodeling are adaptive responses present in systemic arterial hypertension that can result in silent ischemia and neurodegeneration, compromising brain connections and cognitive performance (CP). However, CP is affected differently over time, so traditional screening methods may become less sensitive in assessing certain cognitive domains. The study aimed to evaluate whether cerebrovascular hemodynamic parameters can serve as a tool for cognitive screening in hypertensive without clinically manifest cognitive decline. Methods Participants were allocated into groups: non-hypertensive (n = 30) [group 1], hypertensive with systolic blood pressure (SBP) < 140 and diastolic blood pressure (DBP) < 90 mmHg (n = 54) [group 2] and hypertensive with SBP ≥ 140 or DBP ≥ 90 (n = 31) [group 3]. Measurements of blood pressure and middle cerebral artery blood flow velocity were obtained from digital plethysmography and transcranial Doppler. For the cognitive assessment, the Mini Mental State Examination (MMSE), the Montreal Cognitive Assessment (MoCA) and a broad neuropsychological battery were applied. Results Patients in groups 2 and 3 show no significant differences in most of the clinical-epidemiological variables or pulsatility index (p = 0.361), however compared to group 1 and 2, patients in group 3 had greater resistance-area product [RAP] (1.7 [±0.7] vs. 1.2 [±0.2], p < 0.001). There was a negative correlation between RAP, episodic memory (r = -0.277, p = 0.004) and cognitive processing speed (r = -0.319, p = 0.001). Conclusion RAP reflects the real cerebrovascular resistance, regardless of the direct action of antihypertensive on the microcirculation, and seems to be a potential alternative tool for cognitive screening in hypertensive.
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Affiliation(s)
- Michel Ferreira Machado
- Department of Neurology, Hospital das Clínicas, University of São Paulo Medical School, Brazil
| | | | | | | | - Monica S. Yassuda
- Gerontology, School of Arts, Sciences and Humanities, University of São Paulo Medical School, Brazil
| | - Natalia Cristina Moraes
- Department of Neurology, Hospital das Clínicas, University of São Paulo Medical School, Brazil
| | - Claudia Maia Memória
- Department of Neurology, Hospital das Clínicas, University of São Paulo Medical School, Brazil
| | - Edson Bor-Seng-Shu
- Department of Neurology, Hospital das Clínicas, University of São Paulo Medical School, Brazil
| | - Ricardo Nitrini
- Department of Neurology, Hospital das Clínicas, University of São Paulo Medical School, Brazil
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Stone J, Mitrofanis J, Johnstone DM, Robinson SR. Twelve protections evolved for the brain, and their roles in extending its functional life. Front Neuroanat 2023; 17:1280275. [PMID: 38020212 PMCID: PMC10657866 DOI: 10.3389/fnana.2023.1280275] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Accepted: 10/20/2023] [Indexed: 12/01/2023] Open
Abstract
As human longevity has increased, we have come to understand the ability of the brain to function into advanced age, but also its vulnerability with age, apparent in the age-related dementias. Against that background of success and vulnerability, this essay reviews how the brain is protected by (by our count) 12 mechanisms, including: the cranium, a bony helmet; the hydraulic support given by the cerebrospinal fluid; the strategically located carotid body and sinus, which provide input to reflexes that protect the brain from blood-gas imbalance and extremes of blood pressure; the blood brain barrier, an essential sealing of cerebral vessels; the secretion of molecules such as haemopexin and (we argue) the peptide Aβ to detoxify haemoglobin, at sites of a bleed; autoregulation of the capillary bed, which stabilises metabolites in extracellular fluid; fuel storage in the brain, as glycogen; oxygen storage, in the haemoprotein neuroglobin; the generation of new neurones, in the adult, to replace cells lost; acquired resilience, the stress-induced strengthening of cell membranes and energy production found in all body tissues; and cognitive reserve, the ability of the brain to maintain function despite damage. Of these 12 protections, we identify 5 as unique to the brain, 3 as protections shared with all body tissues, and another 4 as protections shared with other tissues but specialised for the brain. These protections are a measure of the brain's vulnerability, of its need for protection. They have evolved, we argue, to maintain cognitive function, the ability of the brain to function despite damage that accumulates during life. Several can be tools in the hands of the individual, and of the medical health professional, for the lifelong care of our brains.
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Affiliation(s)
- Jonathan Stone
- Faculty of Medicine and Health, University of Sydney, Camperdown, NSW, Australia
| | - John Mitrofanis
- Grenoble and Institute of Ophthalmology, Fonds de Dotation Clinatec, Université Grenoble Alpes, University College London, London, United Kingdom
| | - Daniel M. Johnstone
- School of Biomedical Sciences and Pharmacy, University of Newcastle and School of Medical Sciences, The University of Sydney, Camperdown, NSW, Australia
| | - Stephen R. Robinson
- School of Health and Biomedical Sciences, RMIT University, Bundoora, VIC, Australia
- Institute for Breathing and Sleep, Austin Health, Heidelberg, VIC, Australia
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Sanjana F, Delgorio PL, DeConne TM, Hiscox LV, Pohlig RT, Johnson CL, Martens CR. Vascular determinants of hippocampal viscoelastic properties in healthy adults across the lifespan. J Cereb Blood Flow Metab 2023; 43:1931-1941. [PMID: 37395479 PMCID: PMC10676145 DOI: 10.1177/0271678x231186571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 06/14/2023] [Accepted: 06/16/2023] [Indexed: 07/04/2023]
Abstract
Arterial stiffness and cerebrovascular pulsatility are non-traditional risk factors of Alzheimer's disease. However, there is a gap in understanding the earliest mechanisms that link these vascular determinants to brain aging. Changes to mechanical tissue properties of the hippocampus (HC), a brain structure essential for memory encoding, may reflect the impact of vascular dysfunction on brain aging. We tested the hypothesis that arterial stiffness and cerebrovascular pulsatility are related to HC tissue properties in healthy adults across the lifespan. Twenty-five adults underwent measurements of brachial blood pressure (BP), large elastic artery stiffness, middle cerebral artery pulsatility index (MCAv PI), and magnetic resonance elastography (MRE), a sensitive measure of HC viscoelasticity. Individuals with higher carotid pulse pressure (PP) exhibited lower HC stiffness (β = -0.39, r = -0.41, p = 0.05), independent of age and sex. Collectively, carotid PP and MCAv PI significantly explained a large portion of the total variance in HC stiffness (adjusted R2 = 0.41, p = 0.005) in the absence of associations with HC volumes. These cross-sectional findings suggest that the earliest reductions in HC tissue properties are associated with alterations in vascular function.
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Affiliation(s)
- Faria Sanjana
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, DE, USA
| | - Peyton L Delgorio
- Department of Biomedical Engineering, University of Delaware, Newark, DE, USA
| | - Theodore M DeConne
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, DE, USA
| | - Lucy V Hiscox
- Cardiff University Brain Research Imaging Centre (CUBRIC), Cardiff University, Cardiff, UK
| | - Ryan T Pohlig
- Department of Epidemiology, University of Delaware, Newark, DE, USA
| | - Curtis L Johnson
- Department of Biomedical Engineering, University of Delaware, Newark, DE, USA
| | - Christopher R Martens
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, DE, USA
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Aghilinejad A, Amlani F, Mazandarani SP, King KS, Pahlevan NM. Mechanistic insights on age-related changes in heart-aorta-brain hemodynamic coupling using a pulse wave model of the entire circulatory system. Am J Physiol Heart Circ Physiol 2023; 325:H1193-H1209. [PMID: 37712923 PMCID: PMC10908406 DOI: 10.1152/ajpheart.00314.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 08/14/2023] [Accepted: 08/31/2023] [Indexed: 09/16/2023]
Abstract
Age-related changes in aortic biomechanics can impact the brain by reducing blood flow and increasing pulsatile energy transmission. Clinical studies have shown that impaired cardiac function in patients with heart failure is associated with cognitive impairment. Although previous studies have attempted to elucidate the complex relationship between age-associated aortic stiffening and pulsatility transmission to the cerebral network, they have not adequately addressed the effect of interactions between aortic stiffness and left ventricle (LV) contractility (neither on energy transmission nor on brain perfusion). In this study, we use a well-established and validated one-dimensional blood flow and pulse wave computational model of the circulatory system to address how age-related changes in cardiac function and vasculature affect the underlying mechanisms involved in the LV-aorta-brain hemodynamic coupling. Our results reveal how LV contractility affects pulsatile energy transmission to the brain, even with preserved cardiac output. Our model demonstrates the existence of an optimal heart rate (near the normal human heart rate) that minimizes pulsatile energy transmission to the brain at different contractility levels. Our findings further suggest that the reduction in cerebral blood flow at low levels of LV contractility is more prominent in the setting of age-related aortic stiffening. Maintaining optimal blood flow to the brain requires either an increase in contractility or an increase in heart rate. The former consistently leads to higher pulsatile power transmission, and the latter can either increase or decrease subsequent pulsatile power transmission to the brain.NEW & NOTEWORTHY We investigated the impact of major aging mechanisms of the arterial system and cardiac function on brain hemodynamics. Our findings suggest that aging has a significant impact on heart-aorta-brain coupling through changes in both arterial stiffening and left ventricle (LV) contractility. Understanding the underlying physical mechanisms involved here can potentially be a key step for developing more effective therapeutic strategies that can mitigate the contributions of abnormal LV-arterial coupling toward neurodegenerative diseases and dementia.
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Affiliation(s)
- Arian Aghilinejad
- Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, California, United States
| | - Faisal Amlani
- Laboratoire de Mécanique Paris-Saclay, Université Paris-Saclay, Paris, France
| | - Sohrab P Mazandarani
- Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California, United States
| | - Kevin S King
- Barrow Neurological Institute, Phoenix, Arizona, United States
| | - Niema M Pahlevan
- Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, California, United States
- Division of Cardiovascular Medicine, Department of Medicine, University of Southern California, Los Angeles, California, United States
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Sun F. The impact of blood pressure variability on cognition: current limitations and new advances. J Hypertens 2023; 41:888-905. [PMID: 37016905 PMCID: PMC10158606 DOI: 10.1097/hjh.0000000000003422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 01/18/2023] [Accepted: 02/23/2023] [Indexed: 04/06/2023]
Abstract
Dementia is the most common neurodegenerative disease in the aging population. Emerging evidence indicates that blood pressure (BP) variability is correlated with cognitive impairment and dementia independent of mean BP levels. The state-of-the-art review summarizes the latest evidence regarding the impact of BP variability on cognition in cognitively intact populations, patients with mild cognitive impairment, and different dementia types, focusing on the important confounding factors and new advances. This review also summarizes the potential mechanisms underlying the relationship between BP variability and cognitive impairment, and dementia, briefly discussing sex differences in the relationship. At last, current limitations and future perspectives are discussed to optimize BP management in preventing cognitive impairment and dementia.
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Affiliation(s)
- Fen Sun
- Department of Anatomy, College of Basic Medicine
- Key Laboratory of Organ Development and Regeneration of Zhejiang Province, Hangzhou Normal University, Hangzhou, Zhejiang, China
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Steele CN, Oh ES, Wang W, Farmer-Bailey H, Gitomer BY, Chonchol M, Nowak KL. Cerebrovascular Pulsatility Index Is Reduced in Autosomal Dominant Polycystic Kidney Disease. Am J Nephrol 2023; 54:165-174. [PMID: 37231790 PMCID: PMC10529076 DOI: 10.1159/000530583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 03/17/2023] [Indexed: 05/27/2023]
Abstract
INTRODUCTION Cerebrovascular dysfunction, characterized by increased brain pulsatile flow, reduced cerebrovascular reactivity, and cerebral hypoperfusion precedes the onset of dementia and is linked to cognitive dysfunction. Autosomal dominant polycystic kidney disease (ADPKD) may increase the risk of dementia, and intracranial aneurysms are more prevalent in ADPKD patients. However, cerebrovascular function has not been previously characterized in patients with ADPKD. METHODS Using transcranial Doppler, we compared middle cerebral artery (MCA) pulsatility index (PI, cerebrovascular stiffness) and MCA blood velocity response to hypercapnia (normalized for blood pressure and end-tidal CO2, cerebrovascular reactivity) in patients with early-stage ADPKD versus age-matched healthy controls. We also administered the NIH cognitive toolbox (cognitive function) and measured carotid-femoral pulse-wave velocity (PWV, aortic stiffness). RESULTS Fifteen participants with ADPKD (9F, 27 ± 4 yrs, eGFR: 106 ± 22 mL/min/1.73 m2) were compared to 15 healthy controls (8F, 29 ± 4 yrs, eGFR: 109 ± 14 mL/min/1.73 m2). MCA PI was unexpectedly lower in ADPKD (0.71 ± 0.07) versus controls (0.82 ± 0.09 AU; p < 0.001); however, normalized MCA blood velocity in response to hypercapnia did not differ between groups (2.0 ± 1.2 vs. 2.1 ± 0.8 %Δ/mm Hg; p = 0.85). Lower MCA PI was associated with a lower crystalized composite score (cognition), which persisted after adjustment for age, sex, eGFR, and education (β = 0.58, p = 0.007). There was no association of MCA PI with carotid-femoral PWV (r = 0.01, p = 0.96), despite greater carotid-femoral PWV in ADPKD, suggesting MCA PI reflects vascular properties other than arterial stiffness (such as low wall shear stress) in ADPKD. DISCUSSION/CONCLUSION MCA PI is lower in patients with ADPKD. Follow-up research on this observation is merited as low PI has been associated with intracranial aneurysm in other populations.
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Affiliation(s)
- Cortney N Steele
- Division of Renal Diseases and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Ester S Oh
- Division of Renal Diseases and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Wei Wang
- Division of Renal Diseases and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Heather Farmer-Bailey
- Division of Renal Diseases and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Berenice Y Gitomer
- Division of Renal Diseases and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Michel Chonchol
- Division of Renal Diseases and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Kristen L Nowak
- Division of Renal Diseases and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
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Johnstone DM, Mitrofanis J, Stone J. The brain's weakness in the face of trauma: How head trauma causes the destruction of the brain. Front Neurosci 2023; 17:1141568. [PMID: 36950132 PMCID: PMC10026135 DOI: 10.3389/fnins.2023.1141568] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 02/15/2023] [Indexed: 03/06/2023] Open
Abstract
Of all our organs, the brain is perhaps the best protected from trauma. The skull has evolved to enclose it and, within the skull, the brain floats in a protective bath of cerebrospinal fluid. It is becoming evident, however, that head trauma experienced in young adult life can cause a dementia that appears decades later. The level of trauma that induces such destruction is still being assessed but includes levels well below that which cracks the skull or causes unconsciousness or concussion. Clinically this damage appears as dementia, in people who played body-contact sports in their youth or have survived accidents or the blasts of combat; and appears also, we argue, in old age, without a history of head trauma. The dementias have been given different names, including dementia pugilistica (affecting boxers), chronic traumatic encephalopathy (following certain sports, particularly football), traumatic brain injury (following accidents, combat) and Alzheimer's (following decades of life). They share common features of clinical presentation and neuropathology, and this conceptual analysis seeks to identify features common to these forms of brain injury and to identify where in the brain the damage common to them occurs; and how it occurs, despite the protection provided by the skull and cerebrospinal fluid. The analysis suggests that the brain's weak point in the face of trauma is its capillary bed, which is torn by the shock of trauma. This identification in turn allows discussion of ways of delaying, avoiding and even treating these trauma-induced degenerations.
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Affiliation(s)
- Daniel M. Johnstone
- School of Biomedical Sciences and Pharmacy, University of Newcastle and School of Medical Sciences, The University of Sydney, Darlington, NSW, Australia
| | - John Mitrofanis
- Fonds de Dotation Clinatec, Université Grenoble Alpes, France and Institute of Ophthalmology, University College London, London, United Kingdom
| | - Jonathan Stone
- Honorary Associate, Centenary Institute and University of Sydney, Darlington, NSW, Australia
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King DLO, Henson RN, Kievit R, Wolpe N, Brayne C, Tyler LK, Rowe JB, Tsvetanov KA. Distinct components of cardiovascular health are linked with age-related differences in cognitive abilities. Sci Rep 2023; 13:978. [PMID: 36653428 PMCID: PMC9849401 DOI: 10.1038/s41598-022-27252-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 12/28/2022] [Indexed: 01/19/2023] Open
Abstract
Cardiovascular ageing contributes to cognitive impairment. However, the unique and synergistic contributions of multiple cardiovascular factors to cognitive function remain unclear because they are often condensed into a single composite score or examined in isolation. We hypothesized that vascular risk factors, electrocardiographic features and blood pressure indices reveal multiple latent vascular factors, with independent contributions to cognition. In a population-based deep-phenotyping study (n = 708, age 18-88), path analysis revealed three latent vascular factors dissociating the autonomic nervous system response from two components of blood pressure. These three factors made unique and additive contributions to the variability in crystallized and fluid intelligence. The discrepancy in fluid relative to crystallized intelligence, indicative of cognitive decline, was associated with a latent vascular factor predominantly expressing pulse pressure. This suggests that higher pulse pressure is associated with cognitive decline from expected performance. The effect was stronger in older adults. Controlling pulse pressure may help to preserve cognition, particularly in older adults. Our findings highlight the need to better understand the multifactorial nature of vascular aging.
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Affiliation(s)
- Deborah L O King
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 0SP, UK.
- Department of Psychology, Centre for Speech, Language and the Brain, University of Cambridge, Cambridge, CB23 6HT, UK.
| | - Richard N Henson
- Department of Psychiatry, University of Cambridge, Cambridge, CB2 2QQ, UK
- Medical Research Council Cognition and Brain Sciences Unit, Cambridge, CB2 7EF, UK
- Cambridge Centre for Ageing and Neuroscience (Cam-CAN), University of Cambridge and MRC Cognition and Brain Sciences Unit, Cambridge, CB2 7EF, UK
| | - Rogier Kievit
- Donders Research Institute for Brain, Cognition and Behaviour, Radboud University, 6525 AJ, Nijmegen, The Netherlands
| | - Noham Wolpe
- Department of Psychiatry, University of Cambridge, Cambridge, CB2 2QQ, UK
- Department of Physical Therapy, The Stanley Steer School of Health Professions, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Carol Brayne
- Cambridge Public Health, Cambridge Public Health, University of Cambridge, Cambridge, CB2 0SR, UK
| | - Lorraine K Tyler
- Department of Psychology, Centre for Speech, Language and the Brain, University of Cambridge, Cambridge, CB23 6HT, UK
- Cambridge Centre for Ageing and Neuroscience (Cam-CAN), University of Cambridge and MRC Cognition and Brain Sciences Unit, Cambridge, CB2 7EF, UK
| | - James B Rowe
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 0SP, UK
- Medical Research Council Cognition and Brain Sciences Unit, Cambridge, CB2 7EF, UK
- Cambridge Centre for Ageing and Neuroscience (Cam-CAN), University of Cambridge and MRC Cognition and Brain Sciences Unit, Cambridge, CB2 7EF, UK
| | - Kamen A Tsvetanov
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 0SP, UK
- Department of Psychology, Centre for Speech, Language and the Brain, University of Cambridge, Cambridge, CB23 6HT, UK
- Cambridge Centre for Ageing and Neuroscience (Cam-CAN), University of Cambridge and MRC Cognition and Brain Sciences Unit, Cambridge, CB2 7EF, UK
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Matsuzono K, Suzuki M, Anan Y, Ozawa T, Mashiko T, Koide R, Tanaka R, Fujimoto S. Spontaneous Echo Contrast in the Left Atrium and Aortic-Arch Atheroma, Detected by Transesophageal Echocardiography, Was Negatively Correlated with Cognitive Function. J Alzheimers Dis 2023; 91:673-681. [PMID: 36463447 DOI: 10.3233/jad-220763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
BACKGROUND The relationship between transesophageal echocardiography findings and cognitive function. OBJECTIVE This study aimed to establish an association between transesophageal echocardiography findings and cognitive function in stroke survivors. METHODS A single-center study was conducted between April 1, 2017 and March 31, 2022. All subjects that were included had a past history of ischemic stroke and were admitted after >21 days from onset. The participants underwent cognitive function tests including a Mini-Mental State Examination, Revised Hasegawa Dementia Scale, Frontal Assessment Battery, and transesophageal echocardiography. RESULTS The results of 126 participants were analyzed. The cognitive function of participants with a spontaneous echo contrast (+) in the left atrium including appendage or of those with an aorta-arch plaque with a maximum thickness ≥4 mm significantly worse while neither the patent foramen ovale nor the branch extending plaque influenced cognitive function (The median cognitive scores of the spontaneous echo contrast (-) versus (+) were 26 versus 22, p < 0.01**, 26 versus 21, p < 0.001***, and 14 versus 11, p < 0.01**. Those of the aortic-arch plaque max thickness (<4 mm) versus (≥4 mm) were 26 versus 25, p < 0.05*, 27 versus 24, p < 0.05*, and 15 versus 13, p < 0.05*). CONCLUSION Our findings show that spontaneous echo contrast in the left atrium and aortic-arch atheroma detected by transesophageal echocardiography, were negatively associated with cognitive function.
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Affiliation(s)
- Kosuke Matsuzono
- Division of Neurology, Department of Medicine, Jichi Medical University, Tochigi, Japan
| | - Masayuki Suzuki
- Division of Neurology, Department of Medicine, Jichi Medical University, Tochigi, Japan
| | - Yuhei Anan
- Division of Neurology, Department of Medicine, Jichi Medical University, Tochigi, Japan
| | - Tadashi Ozawa
- Division of Neurology, Department of Medicine, Jichi Medical University, Tochigi, Japan
| | - Takafumi Mashiko
- Division of Neurology, Department of Medicine, Jichi Medical University, Tochigi, Japan
| | - Reiji Koide
- Division of Neurology, Department of Medicine, Jichi Medical University, Tochigi, Japan
| | - Ryota Tanaka
- Division of Neurology, Department of Medicine, Jichi Medical University, Tochigi, Japan
| | - Shigeru Fujimoto
- Division of Neurology, Department of Medicine, Jichi Medical University, Tochigi, Japan
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Oh ES, Freeberg KA, Steele CN, Wang W, Farmer‐Bailey H, Coppock ME, Seals DR, Chonchol M, Rossman MJ, Craighead DH, Nowak KL. Cerebrovascular pulsatility index is higher in chronic kidney disease. Physiol Rep 2023; 11:e15561. [PMID: 36636757 PMCID: PMC9837424 DOI: 10.14814/phy2.15561] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 12/16/2022] [Accepted: 12/19/2022] [Indexed: 06/17/2023] Open
Abstract
Patients with chronic kidney disease (CKD) are more likely to die of cardiovascular diseases, including cerebrovascular disease, than to progress to end-stage kidney disease. Cerebrovascular dysfunction, characterized by reduced cerebrovascular reactivity, cerebral hypoperfusion, and increased pulsatile flow within the brain, precedes the onset of dementia and is linked to cognitive dysfunction. However, whether impaired cerebrovascular function is present in non-dialysis dependent CKD is largely unknown. Using transcranial Doppler, we compared middle cerebral artery (MCA) blood velocity response to hypercapnia (normalized for blood pressure and end-tidal CO2 ; a measure of cerebrovascular reactivity) and MCA pulsatility index (PI; a measure of cerebrovascular stiffness) in patients with stage 3-4 CKD vs. age-matched healthy controls. We also administered the NIH cognitive toolbox (cognitive function), measured carotid-femoral pulse-wave velocity (PWV; aortic stiffness), and assessed ex vivo nitric oxide (NO) and reactive oxygen species (ROS) production from human brain endothelial cells incubated with serum obtained from study participants. MCA PI was higher in patients with CKD vs. controls; however, normalized MCA blood velocity response to hypercapnia did not differ between groups. Similar results were observed in a validation cohort of midlife and older adults divided by the median estimated glomerular filtration rate (eGFR). MCA PI was associated with greater large-elastic artery stiffness (carotid-femoral PWV), worse executive function (trails B time), lower eGFR, and higher ex vivo ROS production. These data suggest that impaired kidney function is associated with greater cerebrovascular stiffness, which may contribute to the known increased risk for cognitive impairment in patients with CKD.
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Affiliation(s)
- Ester S. Oh
- Division of Renal Diseases and HypertensionUniversity of Colorado Anschutz Medical CampusAuroraColoradoUSA
| | - Kaitlin A. Freeberg
- Department of Integrative PhysiologyUniversity of Colorado BoulderBoulderColoradoUSA
| | - Cortney N. Steele
- Division of Renal Diseases and HypertensionUniversity of Colorado Anschutz Medical CampusAuroraColoradoUSA
| | - Wei Wang
- Division of Renal Diseases and HypertensionUniversity of Colorado Anschutz Medical CampusAuroraColoradoUSA
| | - Heather Farmer‐Bailey
- Division of Renal Diseases and HypertensionUniversity of Colorado Anschutz Medical CampusAuroraColoradoUSA
| | - McKinley E. Coppock
- Department of Integrative PhysiologyUniversity of Colorado BoulderBoulderColoradoUSA
| | - Douglas R. Seals
- Department of Integrative PhysiologyUniversity of Colorado BoulderBoulderColoradoUSA
| | - Michel Chonchol
- Division of Renal Diseases and HypertensionUniversity of Colorado Anschutz Medical CampusAuroraColoradoUSA
| | - Matthew J. Rossman
- Department of Integrative PhysiologyUniversity of Colorado BoulderBoulderColoradoUSA
| | - Daniel H. Craighead
- Department of Integrative PhysiologyUniversity of Colorado BoulderBoulderColoradoUSA
| | - Kristen L. Nowak
- Division of Renal Diseases and HypertensionUniversity of Colorado Anschutz Medical CampusAuroraColoradoUSA
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12
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Abstract
This review deals with an unwelcome reality about several forms of dementia, including Alzheimer's disease- that these dementias are caused, in part or whole, by the aging of the vasculature. Since the vasculature ages in us all, dementia is our fate, sealed by the realit!ies of the circulation; it is not a disease with a cure pending. Empirically, cognitive impairment before our 7th decade is uncommon and considered early, while a diagnosis in our 11th decade is late but common in that cohort (>40%). Projections from earlier ages suggest that the prevalence of dementia in people surviving into their 12th decade exceeds 80%. We address the question why so few of many interventions known to delay dementia are recognized as therapy; and we try to resolve this few-and-many paradox, identifying opportunities for better treatment, especially pre-diagnosis. The idea of dementia as a fate is resisted, we argue, because it negates the hope of a cure. But the price of that hope is lost opportunity. An approach more in line with the evidence, and more likely to limit suffering, is to understand the damage that accumulates with age in the cerebral vasculature and therefore in the brain, and which eventually gives rise to cognitive symptoms in late life, too often leading to dementia. We argue that hope should be redirected to delaying that damage and with it the onset of cognitive loss; and, for each individual, it should be redirected to a life-long defense of their brain.
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Affiliation(s)
- Marcus J Andersson
- Faculty of Medicine and Health, University of Sydney, Camperdown, NSW, Australia
| | - Jonathan Stone
- School of Medical Sciences and Faculty of Medicine and Health, University of Sydney, Camperdown, NSW, Australia
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13
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Abstract
Although the cause(s) of Alzheimer's disease in the majority of cases remains elusive, it has long been associated with hypertension. In animal models of the disease, hypertension has been shown to exacerbate Alzheimer-like pathology and behavior, while in humans, hypertension during mid-life increases the risk of developing the disease later in life. Unfortunately, once individuals are diagnosed with the disease, there are few therapeutic options available. There is neither an effective symptomatic treatment, one that treats the debilitating cognitive and memory deficits, nor, more importantly, a neuroprotective treatment, one that stops the relentless progression of the pathology. Further, there is no specific preventative treatment that offsets the onset of the disease. A key factor or clue in this quest for an effective preventative and therapeutic treatment may lie in the contribution of hypertension to the disease. In this review, we explore the idea that photobiomodulation, the application of specific wavelengths of light onto body tissues, can reduce the neuropathology and behavioral deficits in Alzheimer's disease by controlling hypertension. We suggest that treatment with photobiomodulation can be an effective preventative and therapeutic option for this neurodegenerative disease.
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Affiliation(s)
- Audrey Valverde
- Université Grenoble Alpes, Fonds de dotation Clinatec, Grenoble, France
| | - John Mitrofanis
- Université Grenoble Alpes, Fonds de dotation Clinatec, Grenoble, France,
Institute of Ophthalmology, University College London, London, United Kingdom,Correspondence to: John Mitrofanis, E-mail:
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14
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Lillie MA, Vogl AW, Gerard SG, Raverty S, Shadwick RE. Retia mirabilia: Protecting the cetacean brain from locomotion-generated blood pressure pulses. Science 2022; 377:1452-1456. [PMID: 36137023 DOI: 10.1126/science.abn3315] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Cetaceans have massive vascular plexuses (retia mirabilia) whose function is unknown. All cerebral blood flow passes through these retia, and we hypothesize that they protect cetacean brains from locomotion-generated pulsatile blood pressures. We propose that cetaceans have evolved a pulse-transfer mechanism that minimizes pulsatility in cerebral arterial-to-venous pressure differentials without dampening the pressure pulses themselves. We tested this hypothesis using a computational model based on morphology from 11 species and found that the large arterial capacitance in the retia, coupled with the small extravascular capacitance in the cranium and vertebral canal, could protect the cerebral vasculature from 97% of systemic pulsatility. Evolution of the retial complex in cetaceans-likely linked to the development of dorsoventral fluking-offers a distinctive solution to adverse locomotion-generated vascular pulsatility.
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Affiliation(s)
- M A Lillie
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | - A W Vogl
- Life Sciences Institute and Department of Cellular & Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
| | - S G Gerard
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | - S Raverty
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada.,Animal Health Centre, Ministry of Agriculture, Abbotsford, BC, Canada
| | - R E Shadwick
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
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15
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Trumbore CN, Raghunandan A. An Alzheimer's Disease Mechanism Based on Early Pathology, Anatomy, Vascular-Induced Flow, and Migration of Maximum Flow Stress Energy Location with Increasing Vascular Disease. J Alzheimers Dis 2022; 90:33-59. [PMID: 36155517 DOI: 10.3233/jad-220622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
This paper suggests a chemical mechanism for the earliest stages of Alzheimer's disease (AD). Cerebrospinal fluid (CSF) flow stresses provide the energy needed to induce molecular conformation changes leading to AD by initiating amyloid-β (Aβ) and tau aggregation. Shear and extensional flow stresses initiate aggregation in the laboratory and in natural biophysical processes. Energy-rich CSF flow regions are mainly found in lower brain regions. MRI studies reveal flow stress "hot spots" in basal cisterns and brain ventricles that have chaotic flow properties that can distort molecules such as Aβ and tau trapped in these regions into unusual conformations. Such fluid disturbance is surrounded by tissue deformation. There is strong mapping overlap between the locations of these hot spots and of early-stage AD pathology. Our mechanism creates pure and mixed protein dimers, followed by tissue surface adsorption, and long-term tissue agitation ultimately inducing chemical reactions forming more stable, toxic oligomer seeds that initiate AD. It is proposed that different flow stress energies and flow types in different basal brain regions produce different neurotoxic aggregates. Proliferating artery hardening is responsible for enhanced heart systolic pulses that drive energetic CSF pulses, whose critical maximum systolic pulse energy location migrates further from the heart with increasing vascular disease. Two glymphatic systems, carotid and basilar, are suggested to contain the earliest Aβ and tau AD disease pathologies. A key to the proposed AD mechanism is a comparison of early chronic traumatic encephalopathy and AD pathologies. Experiments that test the proposed mechanism are needed.
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Affiliation(s)
- Conrad N Trumbore
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, USA
| | - Aditya Raghunandan
- Department of Mechanical Engineering, University of Rochester, Rochester, NY, USA
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16
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Birch AA, El-Bouri WK, Marchbanks RJ, Moore LA, Campbell-Bell CM, Kipps CM, Bulters DO. Pulsatile tympanic membrane displacement is associated with cognitive score in healthy subjects. Cereb Circ Cogn Behav 2022; 3:100132. [PMID: 36324393 PMCID: PMC9616339 DOI: 10.1016/j.cccb.2022.100132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 02/17/2022] [Accepted: 02/27/2022] [Indexed: 06/16/2023]
Abstract
To test the hypothesis that pulsing of intracranial pressure has an association with cognition, we measured cognitive score and pulsing of the tympanic membrane in 290 healthy subjects. This hypothesis was formed on the assumptions that large intracranial pressure pulses impair cognitive performance and tympanic membrane pulses reflect intracranial pressure pulses. 290 healthy subjects, aged 20-80 years, completed the Montreal Cognitive Assessment Test. Spontaneous tympanic membrane displacement during a heart cycle was measured from both ears in the sitting and supine position. We applied multiple linear regression, correcting for age, heart rate, and height, to test for an association between cognitive score and spontaneous tympanic membrane displacement. Significance was set at P < 0.0125 (Bonferroni correction.) A significant association was seen in the left supine position (p = 0.0076.) The association was not significant in the right ear supine (p = 0.28) or in either ear while sitting. Sub-domains of the cognitive assessment revealed that executive function, language and memory have been primarily responsible for this association. In conclusion, we have found that spontaneous pulses of the tympanic membrane are associated with cognitive performance and believe this reflects an association between cognitive performance and intracranial pressure pulses.
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Affiliation(s)
- Anthony A. Birch
- Neurological Physics Group, Department of Medical Physics, University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK
- University of Southampton, Faculty of Medicine, Southampton, SO17 1BJ, UK
| | - Wahbi K. El-Bouri
- Neurological Physics Group, Department of Medical Physics, University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK
- University of Southampton, Faculty of Engineering and Physical Sciences, Southampton, SO17 1BJ, UK
- Liverpool Centre for Cardiovascular Sciences, Department of Cardiovascular and Metabolic Medicine, University of Liverpool, Liverpool, UK
| | - Robert J. Marchbanks
- Neurological Physics Group, Department of Medical Physics, University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK
- University of Southampton, Faculty of Medicine, Southampton, SO17 1BJ, UK
| | - Laura A. Moore
- Neurological Physics Group, Department of Medical Physics, University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK
| | - Cherith M. Campbell-Bell
- Neurological Physics Group, Department of Medical Physics, University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK
| | - Christopher M. Kipps
- University of Southampton, Faculty of Medicine, Southampton, SO17 1BJ, UK
- Department of Neurology, University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK
| | - Diederik O. Bulters
- University of Southampton, Faculty of Medicine, Southampton, SO17 1BJ, UK
- Department of Neurosurgery, University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK
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17
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Roca F, Rougette K, Zmuda L, Noel G, Larose S, Bordage M, Chassagne P. Association between orthostatic blood pressure dysregulation and geriatric syndromes: a cross-sectional study. BMC Geriatr 2022; 22. [PMID: 35219308 PMCID: PMC8881862 DOI: 10.1186/s12877-022-02844-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Accepted: 01/24/2022] [Indexed: 11/15/2022] Open
Abstract
Background Orthostatic blood pressure dysregulation, including orthostatic hypotension (OH) and orthostatic hypertension (OHT), is common in the elderly. The association between OH and, to a lesser extent, OHT with geriatric syndromes is controversial and little investigated. Our objective was to assess the association between orthostatic blood pressure dysregulation and geriatric syndromes in an ambulatory outpatient population. Methods This observational study included all outpatients for whom a one-visit comprehensive geriatric assessment was performed during a year. OH was defined as a decrease of at least 20 mmHg in systolic blood pressure (SBP) and/or 10 mmHg in diastolic blood pressure (DBP) after 1 or 3 min of standing. OHT was defined as an increase of more than 20 mmHg in SBP after 1 or 3 min of standing. Comorbidities, drugs regimen, a history of previous falls, nutritional, frailty, functional and cognitive status were compared between patients with OHT or OH and controls (NOR). Results Five hundred thirty patients (mean age: 82.9 ± 5.1 years) were included. 19.6% had an OH and 22.3% an OHT. OHT patients were more frequently female, had more diabetes and a lower resting SBP than patients with NOR. OH patients had a higher resting SBP than NOR. After adjusting for age, sex, resting SBP and diabetes, OHT was associated with a low walking speed (OR = 1.332[1.009–1.758]; p = 0.043) and severe cognitive impairment at MMSe score (OR = 1.629[1.070–1.956]; p = 0.016) compared to NOR. Conversely, OH was associated with a lower grip strength (p = 0.016) than NOR. Conclusion OHT and OH are common in elderly but associated with different geriatric phenotypes. Supplementary Information The online version contains supplementary material available at 10.1186/s12877-022-02844-8.
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18
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Joseph-Pauline S, Morrison N, Braccia M, Payne A, Gugerty L, Mostoller J, Lecker P, Tsai EJ, Kim J, Martin M, Brahmbhatt R, Gorski G, Gerhart J, George-Weinstein M, Stone J, Purushothuman S, Bravo-Nuevo A. Acute Response and Neuroprotective Role of Myo/Nog Cells Assessed in a Rat Model of Focal Brain Injury. Front Neurosci 2021; 15:780707. [PMID: 34949984 PMCID: PMC8689062 DOI: 10.3389/fnins.2021.780707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 11/02/2021] [Indexed: 11/13/2022] Open
Abstract
Focal brain injury in the form of a needlestick (NS) results in cell death and induces a self-protective response flanking the lesion. Myo/Nog cells are identified by their expression of bone morphogenetic protein inhibitor Noggin, brain-specific angiogenesis inhibitor 1 (BAI1) and the skeletal muscle specific transcription factor MyoD. Myo/Nog cells limit cell death in two forms of retinopathy. In this study, we examined the acute response of Myo/Nog cells to a NS lesion that extended from the rat posterior parietal cortex to the hippocampus. Myo/Nog cells were identified with antibodies to Noggin and BAI1. These cells were the primary source of both molecules in the uninjured and injured brain. One day after the NS, the normally small population of Myo/Nog cells expanded approximately eightfold within a 1 mm area surrounding the lesion. Myo/Nog cells were reduced by approximately 50% along the lesion with an injection of the BAI1 monoclonal antibody and complement. The number of dying cells, identified by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL), was unchanged at this early time point in response to the decrease in Myo/Nog cells. However, increasing the number of Myo/Nog cells within the lesion by injecting BAI1-positive (+) cells isolated from the brains of other animals, significantly reduced cell death and increased the number of NeuN+ neurons compared to brains injected with phosphate buffered saline or exogenous BAI1-negative cells. These findings demonstrate that Myo/Nog cells rapidly react to injury within the brain and increasing their number within the lesion is neuroprotective.
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Affiliation(s)
| | - Nathan Morrison
- Philadelphia College of Osteopathic Medicine, Philadelphia, PA, United States
| | - Michael Braccia
- Philadelphia College of Osteopathic Medicine, Philadelphia, PA, United States
| | - Alana Payne
- Philadelphia College of Osteopathic Medicine, Philadelphia, PA, United States
| | - Lindsay Gugerty
- Philadelphia College of Osteopathic Medicine, Philadelphia, PA, United States
| | - Jesse Mostoller
- Philadelphia College of Osteopathic Medicine, Philadelphia, PA, United States
| | - Paul Lecker
- Philadelphia College of Osteopathic Medicine, Philadelphia, PA, United States
| | - E-Jine Tsai
- Philadelphia College of Osteopathic Medicine, Philadelphia, PA, United States
| | - Jessica Kim
- Philadelphia College of Osteopathic Medicine, Philadelphia, PA, United States
| | - Mark Martin
- Philadelphia College of Osteopathic Medicine, Philadelphia, PA, United States
| | - Rushil Brahmbhatt
- Philadelphia College of Osteopathic Medicine, Philadelphia, PA, United States
| | - Grzegorz Gorski
- Philadelphia College of Osteopathic Medicine, Philadelphia, PA, United States
| | - Jacquelyn Gerhart
- Philadelphia College of Osteopathic Medicine, Philadelphia, PA, United States
| | | | - Jonathan Stone
- School of Medical Sciences, University of Sydney, Sydney, NSW, Australia.,Discipline of Physiology, University of Sydney, Sydney, NSW, Australia
| | - Sivaraman Purushothuman
- Brain and Mind Centre and Central Clinical School, University of Sydney, Sydney, NSW, Australia
| | - Arturo Bravo-Nuevo
- Philadelphia College of Osteopathic Medicine, Philadelphia, PA, United States
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19
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Dessalles CA, Ramón-Lozano C, Babataheri A, Barakat AI. Luminal flow actuation generates coupled shear and strain in a microvessel-on-chip. Biofabrication 2021; 14. [PMID: 34592728 DOI: 10.1088/1758-5090/ac2baa] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 09/30/2021] [Indexed: 12/12/2022]
Abstract
In the microvasculature, blood flow-derived forces are key regulators of vascular structure and function. Consequently, the development of hydrogel-based microvessel-on-chip systems that strive to mimic thein vivocellular organization and mechanical environment has received great attention in recent years. However, despite intensive efforts, current microvessel-on-chip systems suffer from several limitations, most notably failure to produce physiologically relevant wall strain levels. In this study, a novel microvessel-on-chip based on the templating technique and using luminal flow actuation to generate physiologically relevant levels of wall shear stress and circumferential stretch is presented. Normal forces induced by the luminal pressure compress the surrounding soft collagen hydrogel, dilate the channel, and create large circumferential strain. The fluid pressure gradient in the system drives flow forward and generates realistic pulsatile wall shear stresses. Rigorous characterization of the system reveals the crucial role played by the poroelastic behavior of the hydrogel in determining the magnitudes of the wall shear stress and strain. The experimental measurements are combined with an analytical model of flow in both the lumen and the porous hydrogel to provide an exceptionally versatile user manual for an application-based choice of parameters in microvessels-on-chip. This unique strategy of flow actuation adds a dimension to the capabilities of microvessel-on-chip systems and provides a more general framework for improving hydrogel-basedin vitroengineered platforms.
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Affiliation(s)
- Claire A Dessalles
- LadHyX, CNRS, Ecole polytechnique, Institut polytechnique de Paris, 91120 Palaiseau, France
| | - Clara Ramón-Lozano
- LadHyX, CNRS, Ecole polytechnique, Institut polytechnique de Paris, 91120 Palaiseau, France
| | - Avin Babataheri
- LadHyX, CNRS, Ecole polytechnique, Institut polytechnique de Paris, 91120 Palaiseau, France
| | - Abdul I Barakat
- LadHyX, CNRS, Ecole polytechnique, Institut polytechnique de Paris, 91120 Palaiseau, France
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20
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Mohammadi H, Peng K, Kassab A, Nigam A, Bherer L, Lesage F, Joanette Y. Cortical thinning is associated with brain pulsatility in older adults: An MRI and NIRS study. Neurobiol Aging 2021; 106:103-18. [PMID: 34274697 DOI: 10.1016/j.neurobiolaging.2021.05.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 03/29/2021] [Accepted: 05/03/2021] [Indexed: 11/21/2022]
Abstract
Aging is accompanied by global brain atrophy occurring unequally across the brain. Cortical thinning is seen with aging with a larger loss in the frontal and temporal subregions. We explored the link between regional cortical thickness and regional cerebral pulsatility. Sixty healthy individuals were divided into two age groups, young (aged 19-31) and older (aged 65-75) adults. Each participant underwent a near-infrared spectroscopy (NIRS) scan to index regional brain pulsatility from cerebral pulse-transit-time-to-the peak-of-the-pulse (PTTp), an anatomical magnetic resonance imaging (MRI) and a phase-contrast MRI (PC-MRI) scan to measure arterial and cerebrospinal fluid (CSF) pulsatility. In older adults, the greatest association between cerebral pulsatility and cortical thickness was found in superior and middle temporal and superior, middle and inferior frontal areas, which are the regions perfused first by the internal carotid arteries. This association dropped in the postcentral and superior parietal regions. These findings suggest higher brain pulsatility as a potential risk factor contributing to cortical thinning for some brain regions more than others.
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21
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Dehhaghi M, Kazemi Shariat Panahi H, Braidy N, Guillemin GJ. Herpetosiphon Secondary Metabolites Inhibit Amyloid-β Toxicity in Human Primary Astrocytes. J Alzheimers Dis 2021; 76:423-433. [PMID: 32474470 DOI: 10.3233/jad-200116] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
BACKGROUND The accumulation of extracellular plaques containing amyloid-β protein (Aβ) in the brain is one of the main pathological hallmarks of Alzheimer's disease (AD). Aβ peptide can promote the production of highly volatile free radicals and reactive oxygen species (ROS) that can induce oxidative damage to neurons and astrocytes. At present, numerous studies have investigated the neuroprotective and glioprotective effects of natural products derived from plants, animals, and microorganisms. OBJECTIVE We investigated the glioprotective effect of secondary metabolites obtained from Herpetosiphon sp. HM 1988 against Aβ40-induced toxicity in human primary astrocytes. METHODS The protective effect of bacterial secondary metabolites against Aβ40-induced inducible nitric oxide synthase (iNOS) activity was evaluated using the citrulline assay. To confirm the iNOS activity, nitrite production was assessed using the fluorometric Griess diazotization assay. Intracellular NAD+ depletion and lactate dehydrogenase (LDH) release in human primary astrocytes were also examined using well-established spectrophotometric assays. RESULTS Our results indicate that Aβ40 can induce elevation in iNOS and LDH activities, nitrite production, and cellular energy depletion. Importantly, extract of Herpetosiphon sp. HM 1988 decreased iNOS activity, nitrite production, and LDH release. In addition, metabolites of the strain were able to restore cellular energy deficits through inhibition of NAD+ depletion mediated by Aβ40. CONCLUSION These findings suggest that Herpetosiphon metabolites may represent a promising, novel source for the prevention of Aβ toxicity in AD.
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Affiliation(s)
- Mona Dehhaghi
- Neuroinflammation Group, Faculty of Medicine and Health Sciences, Macquarie University, NSW, Australia
| | | | - Nady Braidy
- Centre for Healthy Brain Ageing, School of Psychiatry, University of New South Wales, Faculty of Medicine, Sydney, Australia
| | - Gilles J Guillemin
- Neuroinflammation Group, Faculty of Medicine and Health Sciences, Macquarie University, NSW, Australia
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22
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Trumbore CN. Shear-Induced Amyloid Aggregation in the Brain: V. Are Alzheimer's and Other Amyloid Diseases Initiated in the Lower Brain and Brainstem by Cerebrospinal Fluid Flow Stresses? J Alzheimers Dis 2021; 79:979-1002. [PMID: 33386802 PMCID: PMC7990457 DOI: 10.3233/jad-201025] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/16/2020] [Indexed: 12/13/2022]
Abstract
Amyloid-β (Aβ) and tau oligomers have been identified as neurotoxic agents responsible for causing Alzheimer's disease (AD). Clinical trials using Aβ and tau as targets have failed, giving rise to calls for new research approaches to combat AD. This paper provides such an approach. Most basic AD research has involved quiescent Aβ and tau solutions. However, studies involving laminar and extensional flow of proteins have demonstrated that mechanical agitation of proteins induces or accelerates protein aggregation. Recent MRI brain studies have revealed high energy, chaotic motion of cerebrospinal fluid (CSF) in lower brain and brainstem regions. These and studies showing CSF flow within the brain have shown that there are two energetic hot spots. These are within the third and fourth brain ventricles and in the neighborhood of the circle of Willis blood vessel region. These two regions are also the same locations as those of the earliest Aβ and tau AD pathology. In this paper, it is proposed that cardiac systolic pulse waves that emanate from the major brain arteries in the lower brain and brainstem regions and whose pulse waves drive CSF flows within the brain are responsible for initiating AD and possibly other amyloid diseases. It is further proposed that the triggering of these diseases comes about because of the strengthening of systolic pulses due to major artery hardening that generates intense CSF extensional flow stress. Such stress provides the activation energy needed to induce conformational changes of both Aβ and tau within the lower brain and brainstem region, producing unique neurotoxic oligomer molecule conformations that induce AD.
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Affiliation(s)
- Conrad N. Trumbore
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, USA
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23
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Balcar VJ, Zeman T, Janout V, Janoutová J, Lochman J, Šerý O. Single Nucleotide Polymorphism rs11136000 of CLU Gene (Clusterin, ApoJ) and the Risk of Late-Onset Alzheimer's Disease in a Central European Population. Neurochem Res 2020; 46:411-422. [PMID: 33206315 DOI: 10.1007/s11064-020-03176-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 11/03/2020] [Accepted: 11/10/2020] [Indexed: 11/28/2022]
Abstract
Clusterin (CLU; also known as apolipoprotein J, ApoJ) is a protein of inconstant structure known to be involved in diverse processes inside and outside of brain cells. CLU can act as a protein chaperon or protein solubilizer, lipid transporter as well as redox sensor and be anti- or proapoptotic, depending on context. Primary structure of CLU is encoded by CLU gene which contains single nucleotide polymorphisms (SNP's) associated with the risk of late-onset Alzheimer's disease (LOAD). Studying a sample of Czech population and using the case-control association approach we identified C allele of the SNP rs11136000 as conferring a reduced risk of LOAD, more so in females than in males. Additionally, data from two smaller subsets of the population sample suggested a possible association of rs11136000 with diabetes mellitus. In a parallel study, we found no association between rs11136000 and mild cognitive impairment (MCI). Our findings on rs11136000 and LOAD contradict those of some previous studies done elsewhere. We discuss the multiple roles of CLU in a broad range of molecular mechanisms that may contribute to the variability of genetic studies of CLU in various ethnic groups. The above discordance notwithstanding, our conclusions support the association of rs1113600 with the risk of LOAD.
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Affiliation(s)
- Vladimir J Balcar
- Bosch Institute and Discipline of Anatomy and Histology, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia. .,Laboratory of Neurobiology and Pathological Physiology, Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic, Veveří 97, 602 00, Brno, Czech Republic.
| | - Tomáš Zeman
- Laboratory of Neurobiology and Pathological Physiology, Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic, Veveří 97, 602 00, Brno, Czech Republic.,Laboratory of Neurobiology and Molecular Psychiatry, Department of Biochemistry, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Vladimír Janout
- Department of Epidemiology and Public Health, Faculty of Medicine, University of Ostrava, Ostrava, Czech Republic.,Present address: Faculty of Health Sciences, Palacký University Olomouc, Olomouc, Czech Republic
| | - Jana Janoutová
- Department of Epidemiology and Public Health, Faculty of Medicine, University of Ostrava, Ostrava, Czech Republic.,Present address: Faculty of Health Sciences, Palacký University Olomouc, Olomouc, Czech Republic
| | - Jan Lochman
- Laboratory of Neurobiology and Pathological Physiology, Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic, Veveří 97, 602 00, Brno, Czech Republic.,Laboratory of Neurobiology and Molecular Psychiatry, Department of Biochemistry, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Omar Šerý
- Laboratory of Neurobiology and Pathological Physiology, Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic, Veveří 97, 602 00, Brno, Czech Republic.,Laboratory of Neurobiology and Molecular Psychiatry, Department of Biochemistry, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
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24
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Abstract
There are no effective treatments available to halt or reverse the progression of age-related cognitive decline and Alzheimer's disease. Thus, there is an urgent need to understand the underlying mechanisms of disease etiology and progression to identify novel therapeutic targets. Age-related changes to the vasculature, particularly increases in stiffness of the large elastic arteries, are now recognized as important contributors to brain aging. There is a growing body of evidence for an association between greater large artery stiffness and cognitive impairment among both healthy older adults and patients with Alzheimer's disease. However, studies in humans are limited to only correlative evidence, whereas animal models allow researchers to explore the causative mechanisms linking arterial stiffness to neurocognitive dysfunction and disease. Recently, several rodent models of direct modulation of large artery stiffness and the consequent effects on the brain have been reported. Common outcomes among these models have emerged, including evidence that greater large artery stiffness causes cerebrovascular dysfunction associated with increased oxidative stress and inflammatory signaling. The purpose of this mini-review is to highlight the recent findings associating large artery stiffness with deleterious brain outcomes, with a specific focus on causative evidence obtained from animal models. We will also discuss the gaps in knowledge that remain in our understanding of how large artery stiffness affects brain function and disease outcomes.
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Affiliation(s)
- Nick R Winder
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | - Emily H Reeve
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | - Ashley E Walker
- Department of Human Physiology, University of Oregon, Eugene, Oregon
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25
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Chiesa ST, Masi S, Shipley MJ, Ellins EA, Fraser AG, Hughes AD, Patel RS, Khir AW, Halcox JP, Singh-Manoux A, Kivimaki M, Celermajer DS, Deanfield JE. Carotid artery wave intensity in mid- to late-life predicts cognitive decline: the Whitehall II study. Eur Heart J 2020; 40:2300-2309. [PMID: 30957863 PMCID: PMC6642727 DOI: 10.1093/eurheartj/ehz189] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 02/07/2019] [Accepted: 03/19/2019] [Indexed: 12/18/2022] Open
Abstract
AIMS Excessive arterial pulsatility may contribute to cognitive decline and risk of dementia via damage to the fragile cerebral microcirculation. We hypothesized that the intensity of downstream-travelling pulsatile waves measured by wave intensity analysis in the common carotid artery during mid- to late-life would be associated with subsequent cognitive decline. METHODS AND RESULTS Duplex Doppler ultrasound was used to calculate peak forward-travelling compression wave intensity (FCWI) within the common carotid artery in 3191 individuals [mean ± standard deviation (SD), age = 61 ± 6 years; 75% male] assessed as part of the Whitehall II study in 2003-05. Serial measures of cognitive function were taken between 2002-04 and 2015-16. The relationship between FCWI and cognitive decline was adjusted for sociodemographic variables, genetic and health-related risk factors, and health behaviours. Mean (SD) 10-year change in standardized global cognitive score was -0.39 (0.18). Higher FCWI at baseline was associated with accelerated cognitive decline during follow-up [difference in 10-year change of global cognitive score per 1 SD higher FCWI = -0.02 (95% confidence interval -0.04 to -0.00); P = 0.03]. This association was largely driven by cognitive changes in individuals with the highest FCWI [Q4 vs. Q1-Q3 = -0.05 (-0.09 to -0.01), P = 0.01], equivalent to an age effect of 1.9 years. Compared to other participants, this group was ∼50% more likely to exhibit cognitive decline (defined as the top 15% most rapid reductions in cognitive function during follow-up) even after adjustments for multiple potential confounding factors [odds ratio 1.49 (1.17-1.88)]. CONCLUSION Elevated carotid artery wave intensity in mid- to late-life predicts faster cognitive decline in long-term follow-up independent of other cardiovascular risk factors.
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Affiliation(s)
- Scott T Chiesa
- National Centre for Cardiovascular Preventions and Outcomes, UCL Institute of Cardiovascular Science, 1 St. Martin's Le Grand, London, UK
| | - Stefano Masi
- National Centre for Cardiovascular Preventions and Outcomes, UCL Institute of Cardiovascular Science, 1 St. Martin's Le Grand, London, UK.,Department of Clinical and Experimental Medicine, Universitá di Pisa, Building 8, S. Chiara Hospital, Via Roma 67, Pisa, Italy
| | - Martin J Shipley
- Department of Epidemiology and Public Health, UCL, 1-19 Torrington Place, London, UK
| | - Elizabeth A Ellins
- Institute of Life Science, Swansea University Medical School, Swansea University, Singleton Park, Swansea, UK
| | - Alan G Fraser
- School of Medicine, Heath Park, Cardiff, UK.,Department of Cardiology, University Hospital of Wales, Heath Park, Cardiff, UK
| | - Alun D Hughes
- Department of Population Science and Experimental Medicine, UCL Institute of Cardiovascular Science, 69-75 Chenies Mews, London, UK.,Medical Research Council Unit for Lifelong Health and Ageing at UCL, 33 Bedford Place, London, UK
| | - Riyaz S Patel
- National Centre for Cardiovascular Preventions and Outcomes, UCL Institute of Cardiovascular Science, 1 St. Martin's Le Grand, London, UK.,Department of Cardiology, Bart's Heart Centre, St Bartholomew's Hospital, W Smithfield, London, UK
| | - Ashraf W Khir
- Biomedical Engineering Research Theme, Brunel University London, Kingston Lane, Uxbridge, UK
| | - Julian P Halcox
- Institute of Life Science, Swansea University Medical School, Swansea University, Singleton Park, Swansea, UK
| | - Archana Singh-Manoux
- Department of Epidemiology and Public Health, UCL, 1-19 Torrington Place, London, UK.,Inserm U1153, Epidemiology of Ageing and Neurodegenerative Diseases, Faculty of Medicine, University of Paris, 10 Avenue de Verdun, Paris, France
| | - Mika Kivimaki
- Department of Epidemiology and Public Health, UCL, 1-19 Torrington Place, London, UK
| | | | - John E Deanfield
- National Centre for Cardiovascular Preventions and Outcomes, UCL Institute of Cardiovascular Science, 1 St. Martin's Le Grand, London, UK
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26
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Abstract
Elevated pulse pressure can cause blood-brain barrier dysfunction and subsequent adverse neurological changes that may drive or contribute to the development of dementia with age. In short, elevated pulse pressure dysregulates cerebral endothelial cells and increases cellular production of oxidative and inflammatory molecules. The resulting cerebral microvascular damage, along with excessive pulsatile mechanical force, can induce breakdown of the blood-brain barrier, which in turn triggers brain cell impairment and death. We speculate that elevated pulse pressure may also reduce the efficacy of other therapeutic strategies for dementia. For instance, BACE1 inhibitors and anti-amyloid-β biologics reduce amyloid-β deposits in the brain that are thought to be a cause of Alzheimer’s disease, the most prevalent form of dementia. However, upregulation of oxidative and inflammatory molecules and increased amyloid-β secretion by cerebral endothelial cells exposed to elevated pulse pressure may hinder cognitive improvements with these drugs. Additionally, stem or progenitor cell therapy has the potential to repair blood-brain barrier damage, but chronic oxidative and inflammatory stress due to elevated pulse pressure can inhibit stem and progenitor cell regeneration. Finally, we discuss current efforts to repurpose blood pressure medications to prevent or treat dementia. We propose that new drugs or devices should be developed to safely reduce elevated pulse pressure specifically to the brain. Such novel technologies may alleviate an entire downstream pathway of cellular dysfunction, oxidation, inflammation, and amyloidogenesis, thereby preventing pulse-pressure-induced cognitive decline. Furthermore, these technologies may also enhance efficacy of other dementia therapeutics when used in combination.
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Affiliation(s)
- Rachel A Levin
- The Brain Protection Company, Sydney, NSW, Australia.,M.H. Carnegie & Co., Sydney, NSW, Australia
| | - Mark H Carnegie
- The Brain Protection Company, Sydney, NSW, Australia.,M.H. Carnegie & Co., Sydney, NSW, Australia
| | - David S Celermajer
- The Brain Protection Company, Sydney, NSW, Australia.,The Heart Research Institute, Sydney, NSW, Australia
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27
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Baranauskas M, Jurkonis R, Lukoševičius A, Makūnaitė M, Matijošaitis V, Gleiznienė R, Rastenytė D. Ultrasonic Assessment of the Medial Temporal Lobe Tissue Displacements in Alzheimer’s Disease. Diagnostics (Basel) 2020; 10:452. [PMID: 32635379 PMCID: PMC7399840 DOI: 10.3390/diagnostics10070452] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 06/30/2020] [Accepted: 07/01/2020] [Indexed: 12/31/2022] Open
Abstract
We aim to estimate brain tissue displacements in the medial temporal lobe (MTL) using backscattered ultrasound radiofrequency (US RF) signals, and to assess the diagnostic ability of brain tissue displacement parameters for the differentiation of patients with Alzheimer’s disease (AD) from healthy controls (HC). Standard neuropsychological evaluation and transcranial sonography (TCS) for endogenous brain tissue motion data collection are performed for 20 patients with AD and for 20 age- and sex-matched HC in a prospective manner. Essential modifications of our previous method in US waveform parametrization, raising the confidence of micrometer-range displacement signals in the presence of noise, are done. Four logistic regression models are constructed, and receiver operating characteristic (ROC) curve analyses are applied. All models have cut-offs from 61.0 to 68.5% and separate AD patients from HC with a sensitivity of 89.5% and a specificity of 100%. The area under a ROC curve of predicted probability in all models is excellent (from 95.2 to 95.7%). According to our models, AD patients can be differentiated from HC by a sharper morphology of some individual MTL spatial point displacements (i.e., by spreading the spectrum of displacements to the high-end frequencies with higher variability across spatial points within a region), by lower displacement amplitude differences between adjacent spatial points (i.e., lower strain), and by a higher interaction of these attributes.
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28
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Aghilinejad A, Amlani F, King KS, Pahlevan NM. Dynamic Effects of Aortic Arch Stiffening on Pulsatile Energy Transmission to Cerebral Vasculature as A Determinant of Brain-Heart Coupling. Sci Rep 2020; 10:8784. [PMID: 32472027 DOI: 10.1038/s41598-020-65616-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 05/04/2020] [Indexed: 12/17/2022] Open
Abstract
Aortic stiffness increases with age and is a robust predictor of brain pathology including Alzheimer’s and other dementias. Aging causes disproportionate stiffening of the aorta compared with the carotid arteries, reducing protective impedance mismatches at their interface and affecting transmission of destructive pulsatile energy to the cerebral circulation. Recent clinical studies have measured regional stiffness within the aortic arch using pulse wave velocity (PWV) and have found a stronger association with cerebrovascular events than global stiffness measures. However, effects of aortic arch PWV on the transmission of harmful excessive pulsatile energy to the brain is not well-understood. In this study, we use an energy-based analysis of hemodynamic waves to quantify the effect of aortic arch stiffening on transmitted pulsatility to cerebral vasculature, employing a computational approach using a one-dimensional model of the human vascular network. Results show there exists an optimum wave condition—occurring near normal human heart rates—that minimizes pulsatile energy transmission to the brain. This indicates the important role of aortic arch biomechanics on heart-brain coupling. Our results also suggest that energy-based indices of pulsatility combining pressure and flow data are more sensitive to increased stiffness than using flow or pressure pulsatility indices in isolation.
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29
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de Montgolfier O, Thorin-Trescases N, Thorin E. Pathological Continuum From the Rise in Pulse Pressure to Impaired Neurovascular Coupling and Cognitive Decline. Am J Hypertens 2020; 33:375-390. [PMID: 32202623 PMCID: PMC7188799 DOI: 10.1093/ajh/hpaa001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 12/11/2019] [Accepted: 03/03/2020] [Indexed: 12/12/2022] Open
Abstract
The "biomechanical hypothesis" stipulates that with aging, the cumulative mechanical damages to the cerebral microvasculature, magnified by risk factors for vascular diseases, contribute to a breach in cerebral homeostasis producing neuronal losses. In other words, vascular dysfunction affects brain structure and function, and leads to cognitive failure. This is gathered under the term Vascular Cognitive Impairment and Dementia (VCID). One of the main culprits in the occurrence of cognitive decline could be the inevitable rise in arterial pulse pressure due to the age-dependent stiffening of large conductance arteries like the carotids, which in turn, could accentuate the penetration of the pulse pressure wave deeper into the fragile microvasculature of the brain and damage it. In this review, we will discuss how and why the vascular and brain cells communicate and are interdependent, describe the deleterious impact of a vascular dysfunction on brain function in various neurodegenerative diseases and even of psychiatric disorders, and the potential chronic deleterious effects of the pulsatile blood pressure on the cerebral microcirculation. We will also briefly review data from antihypertensive clinical trial aiming at improving or delaying dementia. Finally, we will debate how the aging process, starting early in life, could determine our sensitivity to risk factors for vascular diseases, including cerebral diseases, and the trajectory to VCID.
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Affiliation(s)
- Olivia de Montgolfier
- Faculty of Medicine, Department of Pharmacology and Physiology, Université de Montréal, Montreal, Quebec, Canada
- Montreal Heart Institute, Research Center, Montreal, Quebec, Canada
| | | | - Eric Thorin
- Faculty of Medicine, Department of Pharmacology and Physiology, Université de Montréal, Montreal, Quebec, Canada
- Montreal Heart Institute, Research Center, Montreal, Quebec, Canada
- Faculty of Medicine, Department of Surgery, Université de Montréal, Montreal, Quebec, Canada
- Correspondence: Eric Thorin ()
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30
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Namasivayam M, Adji A, Lin L, Hayward CS, Feneley MP, O’rourke MF, Muller DWM, Jabbour A. Non-Invasive Quantification of Ventricular Contractility, Arterial Elastic Function and Ventriculo-Arterial Coupling from a Single Diagnostic Encounter Using Simultaneous Arterial Tonometry and Magnetic Resonance Imaging. Cardiovasc Eng Technol 2020; 11:283-94. [DOI: 10.1007/s13239-020-00462-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/01/2019] [Accepted: 04/07/2020] [Indexed: 12/31/2022]
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31
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Kennedy G, Meyer D, Hardman RJ, Macpherson H, Scholey AB, Pipingas A. Modelling Modifiable Predictors of Age-Related Cognitive Decline: Exercise, Aortic Stiffness, and the Importance of Physical Fitness. J Alzheimers Dis Rep 2020; 4:79-89. [PMID: 32467878 PMCID: PMC7242822 DOI: 10.3233/adr-190164] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/16/2020] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Previous modelling found that fitness and aortic stiffness both independently predicted spatial working memory (SWM) performance in older people. There is also evidence that greater engagement in moderate intensity exercise contributes to better cognitive performance, potentially working through improving fitness and aortic stiffness. OBJECTIVE To investigate the effect of exercise on the previously established relationships between fitness, aortic stiffness, and SWM, and whether these associations differ between older adults of higher and lower fitness. METHODS One hundred and two residents of independent living facilities, aged 60-90 (M = 77.5, SD = 6.9) participated in the study. Measures included computerized cognitive assessment, the Six-Minute Walk fitness test, the CHAMPS physical activity questionnaire, and aortic pulse wave analysis. Multiple structural equation models were used to test hypotheses. RESULTS Overall, exercise levels had a small additional effect in predicting SWM, working exclusively through fitness, although this was only true for those of lower than average fitness. Additionally, it was found that while fitness was the most important factor in predicting SWM in those of lower fitness, aortic stiffness was the strongest predictor in those of higher fitness. CONCLUSION Fitness and aortic stiffness are strong predictors of cognition in older people, and greater engagement in exercise predicted better cognition in those who were of lower fitness. Fitter older people may benefit more from interventions which target aortic stiffness in order to preserve cognitive performance as they age, while those who are less fit may benefit most from improving fitness first, including through increased physical activity.
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Affiliation(s)
- Greg Kennedy
- Centre for Human Psychopharmacology, Swinburne University of Technology, Melbourne, Australia
| | - Denny Meyer
- Centre for Human Psychopharmacology, Swinburne University of Technology, Melbourne, Australia
| | - Roy J. Hardman
- Centre for Human Psychopharmacology, Swinburne University of Technology, Melbourne, Australia
| | - Helen Macpherson
- Centre for Human Psychopharmacology, Swinburne University of Technology, Melbourne, Australia
- Institute for Physical Activity and Nutrition, Deakin University, Geelong, Australia
| | - Andrew B. Scholey
- Centre for Human Psychopharmacology, Swinburne University of Technology, Melbourne, Australia
| | - Andrew Pipingas
- Centre for Human Psychopharmacology, Swinburne University of Technology, Melbourne, Australia
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32
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Vallet A, Del Campo N, Hoogendijk EO, Lokossou A, Balédent O, Czosnyka Z, Balardy L, Payoux P, Swider P, Lorthois S, Schmidt E. Biomechanical response of the CNS is associated with frailty in NPH-suspected patients. J Neurol 2020; 267:1389-1400. [DOI: 10.1007/s00415-019-09689-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 12/20/2019] [Accepted: 12/23/2019] [Indexed: 12/29/2022]
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de Montgolfier O, Pinçon A, Pouliot P, Gillis MA, Bishop J, Sled JG, Villeneuve L, Ferland G, Lévy BI, Lesage F, Thorin-Trescases N, Thorin É. High Systolic Blood Pressure Induces Cerebral Microvascular Endothelial Dysfunction, Neurovascular Unit Damage, and Cognitive Decline in Mice. Hypertension 2019; 73:217-228. [PMID: 30571552 DOI: 10.1161/hypertensionaha.118.12048] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A chronic and gradual increase in pulse pressure (PP) is associated with cognitive decline and dementia in older individuals, but the mechanisms remain ill-defined. We hypothesized that a chronic elevation of PP would cause brain microvascular endothelial mechanical stress, damage the neurovascular unit, and ultimately induce cognitive impairment in mice, potentially contributing to the progression of vascular dementia and Alzheimer disease. To test our hypothesis, male control wild-type mice and Alzheimer disease model APP/PS1 (amyloid precursor protein/presenilin 1) mice were exposed to a transverse aortic constriction for 6 weeks, creating a PP overload in the right carotid (ipsilateral). We show that the transverse aortic constriction procedure associated with high PP induces a cascade of vascular damages in the ipsilateral parenchymal microcirculation: in wild-type mice, it impairs endothelial dilatory and blood brain barrier functions and causes microbleeds, a reduction in microvascular density, microvascular cell death by apoptosis, leading to severe hypoperfusion and parenchymal cell senescence. These damages were associated with brain inflammation and a significant reduction in learning and spatial memories. In APP/PS1 mice, that endogenously display severe cerebral vascular dysfunctions, microbleeds, parenchymal inflammation and cognitive dysfunction, transverse aortic constriction-induced high PP further aggravates cerebrovascular damage, Aβ (beta-amyloid) accumulation, and prevents learning. Our study, therefore, demonstrates that brain microvessels are vulnerable to a high PP and mechanical stress associated with transverse aortic constriction, promoting severe vascular dysfunction, disruption of the neurovascular unit, and cognitive decline. Hence, chronic elevated amplitude of the PP could contribute to the development and progression of vascular dementia including Alzheimer disease.
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Affiliation(s)
- Olivia de Montgolfier
- From the Department of Pharmacology and Physiology (O.d.M., A.P.), Université de Montréal, Quebec, Canada.,Montreal Heart Institute, Research Center, Quebec, Canada (O.d.M., A.P., M.-A.G., L.V., G.F., F.L., N.T.-T., E.T.)
| | - Anthony Pinçon
- From the Department of Pharmacology and Physiology (O.d.M., A.P.), Université de Montréal, Quebec, Canada.,Montreal Heart Institute, Research Center, Quebec, Canada (O.d.M., A.P., M.-A.G., L.V., G.F., F.L., N.T.-T., E.T.)
| | | | - Marc-Antoine Gillis
- Montreal Heart Institute, Research Center, Quebec, Canada (O.d.M., A.P., M.-A.G., L.V., G.F., F.L., N.T.-T., E.T.)
| | - Jonathan Bishop
- Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Ontario, Canada (J.B., J.G.S.)
| | - John G Sled
- Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Ontario, Canada (J.B., J.G.S.).,Department of Medical Biophysics, University of Toronto, Ontario, Canada (J.G.S.)
| | - Louis Villeneuve
- Montreal Heart Institute, Research Center, Quebec, Canada (O.d.M., A.P., M.-A.G., L.V., G.F., F.L., N.T.-T., E.T.)
| | - Guylaine Ferland
- Department of Nutrition (G.F.), Université de Montréal, Quebec, Canada.,Montreal Heart Institute, Research Center, Quebec, Canada (O.d.M., A.P., M.-A.G., L.V., G.F., F.L., N.T.-T., E.T.)
| | - Bernard I Lévy
- Institut des Vaisseaux et du Sang, Hôpital Lariboisière, Paris, France (B.I.L.)
| | - Frédéric Lesage
- Montreal Heart Institute, Research Center, Quebec, Canada (O.d.M., A.P., M.-A.G., L.V., G.F., F.L., N.T.-T., E.T.).,Ecole Polytechnique de Montréal, Quebec, Canada (P.P., F.L.)
| | - Nathalie Thorin-Trescases
- Montreal Heart Institute, Research Center, Quebec, Canada (O.d.M., A.P., M.-A.G., L.V., G.F., F.L., N.T.-T., E.T.)
| | - Éric Thorin
- Department of Surgery (E.T.), Université de Montréal, Quebec, Canada.,Montreal Heart Institute, Research Center, Quebec, Canada (O.d.M., A.P., M.-A.G., L.V., G.F., F.L., N.T.-T., E.T.)
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O'Rourke MF, Adji A. The role of functional status on the relationship between blood pressure and cognitive decline: the Cardiovascular Health Study. J Hypertens 2019; 37:2500-1. [PMID: 31688295 DOI: 10.1097/HJH.0000000000002263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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35
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San Miguel M, Martin KL, Stone J, Johnstone DM. Photobiomodulation Mitigates Cerebrovascular Leakage Induced by the Parkinsonian Neurotoxin MPTP. Biomolecules 2019; 9:E564. [PMID: 31590236 DOI: 10.3390/biom9100564] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 10/01/2019] [Accepted: 10/01/2019] [Indexed: 12/15/2022] Open
Abstract
The neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is commonly used to model Parkinson’s disease (PD) as it specifically damages the nigrostriatal dopaminergic pathway. Recent studies in mice have, however, provided evidence that MPTP also compromises the integrity of the brain’s vasculature. Photobiomodulation (PBM), the irradiation of tissue with low-intensity red light, mitigates MPTP-induced loss of dopaminergic neurons in the midbrain, but whether PBM also mitigates MPTP-induced damage to the cerebrovasculature has not been investigated. This study aimed to characterize the time course of cerebrovascular disruption following MPTP exposure and to determine whether PBM can mitigate this disruption. Young adult male C57BL/6 mice were injected with 80 mg/kg MPTP or isotonic saline and perfused with fluorescein isothiocyanate FITC-labelled albumin at various time points post-injection. By 7 days post-injection, there was substantial and significant leakage of FITC-labelled albumin into both the substantia nigra pars compacta (SNc; p < 0.0001) and the caudate-putamen complex (CPu; p ≤ 0.0003); this leakage partly subsided by 14 days post-injection. Mice that were injected with MPTP and treated with daily transcranial PBM (670 nm, 50 mW/cm2, 3 min/day), commencing 24 h after MPTP injection, showed significantly less leakage of FITC-labelled albumin in both the SNc (p < 0.0001) and CPu (p = 0.0003) than sham-treated MPTP mice, with levels of leakage that were not significantly different from saline-injected controls. In summary, this study confirms that MPTP damages the brain’s vasculature, delineates the time course of leakage induced by MPTP out to 14 days post-injection, and provides the first direct evidence that PBM can mitigate this leakage. These findings provide new understanding of the use of the MPTP mouse model as an experimental tool and highlight the potential of PBM as a therapeutic tool for reducing vascular dysfunction in neurological conditions.
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Abstract
If cerebrospinal and interstitial fluids move through very narrow brain flow channels, these restrictive surroundings generate varying levels of fluid shear and different shear rates, and dissolved amyloid monomers absorb different shear energies. It is proposed that dissolved amyloid-β protein (Aβ) and other amyloid monomers undergo shear-induced conformational changes that ultimately lead to amyloid monomer aggregation even at very low brain flow and shear rates. Soluble Aβ oligomers taken from diseased brains initiate in vivo amyloid formation in non-diseased brains. The brain environment is apparently responsible for this result. A mechanism involving extensional shear is proposed for the formation of a seed Aβ monomer molecule that ultimately promotes templated conformational change of other Aβ molecules. Under non-quiescent, non-equilibrium conditions, gentle extensional shear within the brain parenchyma, and perhaps even during laboratory preparation of Aβ samples, may be sufficient to cause subtle conformational changes in these monomers. These result from brain processes that significantly lower the high activation energy predicted for the quiescent Aβ dimerization process. It is further suggested that changes in brain location and changes brought about by aging expose Aβ molecules to different shear rates, total shear, and types of shear, resulting in different conformational changes in these molecules. The consequences of such changes caused by variable shear energy are proposed to underlie formation of amyloid strains causing different amyloid diseases. Amyloid researchers are urged to undertake studies with amyloids, anti-amyloid drugs, and antibodies while all of these are under shear conditions similar to those in the brain.
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Affiliation(s)
- Conrad N Trumbore
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, USA
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37
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Raphael CE, Frenneaux M. Wave intensity and cognitive decline: where the heart leads the mind follows. Eur Heart J 2019; 40:2310-2312. [PMID: 31102522 DOI: 10.1093/eurheartj/ehz307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/15/2024] Open
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38
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Hong N. Photobiomodulation as a treatment for neurodegenerative disorders: current and future trends. Biomed Eng Lett 2019; 9:359-366. [PMID: 31456895 DOI: 10.1007/s13534-019-00115-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 04/05/2019] [Accepted: 06/04/2019] [Indexed: 12/12/2022] Open
Abstract
Photobiomodulation (PBM) is a rapidly growing as an innovative therapeutic modality for various types of diseases in recent years. Neuronal degeneration is irreversible process and it is proven to be difficult to slow down or stop the progression. Pharmacologic approaches to slow neuronal degeneration have been studied, but are limited due to concerns about the side effects. Therefore, it is necessary to develop a new therapeutic approach to stabilize neuronal degeneration and achieve neuronal protection against several neurodegenerative diseases. In this review, we have introduced several previous studies showing the positive effect of PBM over neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease and different types of epilepsy. Despite excellent outcomes of animal researches, not many clinical studies are conducted or showed positive outcome of PBM against neurodegenerative disease. To achieve clinical application of PBM against neurodegenerative disorder, determination of exact mechanism and establishment of effective clinical protocol seems to be necessary.
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Affiliation(s)
- Namgue Hong
- Department of Pre-medical Science, College of Medicine, Dankook University, Cheonan, 31116 Republic of Korea
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Kennedy G, Meyer D, Hardman RJ, Macpherson H, Scholey AB, Pipingas A. Physical Fitness and Aortic Stiffness Explain the Reduced Cognitive Performance Associated with Increasing Age in Older People. J Alzheimers Dis 2019; 63:1307-1316. [PMID: 29865082 DOI: 10.3233/jad-171107] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
BACKGROUND Greater physical fitness is associated with reduced rates of cognitive decline in older people; however, the mechanisms by which this occurs are still unclear. One potential mechanism is aortic stiffness, with increased stiffness resulting in higher pulsatile pressures reaching the brain and possibly causing progressive micro-damage. There is limited evidence that those who regularly exercise may have lower aortic stiffness. OBJECTIVE To investigate whether greater fitness and lower aortic stiffness predict better cognitive performance in older people and, if so, whether aortic stiffness mediates the relationship between fitness and cognition. METHODS Residents of independent living facilities, aged 60-90, participated in the study (N = 102). Primary measures included a computerized cognitive assessment battery, pulse wave velocity analysis to measure aortic stiffness, and the Six-Minute Walk test to assess fitness. Based on hierarchical regression analyses, structural equation modelling was used to test the mediation hypothesis. RESULTS Both fitness and aortic stiffness independently predicted Spatial Working Memory (SWM) performance, however no mediating relationship was found. Additionally, the derived structural equation model shows that, in conjunction with BMI and sex, fitness and aortic stiffness explain 33% of the overall variation in SWM, with age no longer directly predicting any variation. CONCLUSIONS Greater fitness and lower aortic stiffness both independently predict better SWM in older people. The strong effect of age on cognitive performance is totally mediated by fitness and aortic stiffness. This suggests that addressing both physical fitness and aortic stiffness may be important to reduce the rate of age associated cognitive decline.
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Affiliation(s)
- Greg Kennedy
- Centre for Human Psychopharmacology, Swinburne University of Technology, Melbourne, Australia
| | - Denny Meyer
- Centre for Human Psychopharmacology, Swinburne University of Technology, Melbourne, Australia
| | - Roy J Hardman
- Centre for Human Psychopharmacology, Swinburne University of Technology, Melbourne, Australia
| | - Helen Macpherson
- Centre for Human Psychopharmacology, Swinburne University of Technology, Melbourne, Australia.,Institute for Physical Activity and Nutrition, Deakin University, Geelong, Australia
| | - Andrew B Scholey
- Centre for Human Psychopharmacology, Swinburne University of Technology, Melbourne, Australia
| | - Andrew Pipingas
- Centre for Human Psychopharmacology, Swinburne University of Technology, Melbourne, Australia
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40
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James NL, Milijasevic Z, Ujhazy A, Edwards G, Jermyn K, Mynard JP, Celermajer DS. The common carotid artery provides significant pressure wave dampening in the young adult sheep. Int J Cardiol Heart Vasc 2019; 23:100343. [PMID: 31321284 PMCID: PMC6612755 DOI: 10.1016/j.ijcha.2019.03.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 03/08/2019] [Accepted: 03/11/2019] [Indexed: 12/05/2022]
Abstract
Background It has been established that the central elastic arteries of the mammalian circulation dampen the high pulse pressure emanating from the left ventricle, so that the pulsations in distal arterioles, such as in the cerebral circulation, are of lower amplitude than more centrally. However, the contribution of the common carotid artery (CCA) to protection of the cerebral microvasculature from high pulse pressure is not known, specifically to what extent viscoelastic energy dissipation in the arterial wall might contribute to the shock absorbing function of the large conduit arteries. Methods Young adult sheep (n = 6) were anaesthetised and their CCAs (n = 7) exposed. Pressure catheters were inserted 10–15 cm apart, proximally and distally in the CCA; a flow probe was placed proximally on the vessel. Results The median dp/dtmax on the pressure rise of the arterial wave upstroke for the proximal CCA was 619 mm Hg/s and for the distal CCA it was significantly lower, at 197 mm Hg/s (p = 0.0156; n = 7). The median pulse pressure of the proximal CCA was 24 mm Hg/s; distal pulse pressure was significantly lower, at 18 mm Hg/s (p = 0.0156; n = 7). The median flow rate was 0.97 L/min with an interquartile range from 0.51 to 1.15 L/min. Conclusions The native CCA in the young adult sheep is an effective “pressure dampener” in the arterial circulation, reducing both pressure slope and pulse pressure, most likely via viscous dampening in the arterial wall.
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Affiliation(s)
- Natalie L. James
- The Brain Protection Company, Sydney, New South Wales, Australia
- Corresponding author at: The Brain Protection Company, 52 Victoria Street, Paddington, NSW 2021, Australia.
| | | | - Anthony Ujhazy
- The Brain Protection Company, Sydney, New South Wales, Australia
| | - Glenn Edwards
- School of Animal and Veterinary Sciences, Charles Sturt University, Wagga Wagga, New South Wales, Australia
| | - Kieri Jermyn
- School of Animal and Veterinary Sciences, Charles Sturt University, Wagga Wagga, New South Wales, Australia
| | - Jonathan P. Mynard
- Heart Research, Clinical Sciences, Murdoch Children's Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Parkville, Victoria, Australia
- Department of Biomedical Engineering, University of Melbourne, Parkville, Victoria, Australia
| | - David S. Celermajer
- Clinical Research Group, The Heart Research Institute, Sydney, New South Wales, Australia
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Palta P, Sharrett AR, Wei J, Meyer ML, Kucharska‐Newton A, Power MC, Deal JA, Jack CR, Knopman D, Wright J, Griswold M, Tanaka H, Mosley TH, Heiss G. Central Arterial Stiffness Is Associated With Structural Brain Damage and Poorer Cognitive Performance: The ARIC Study. J Am Heart Assoc 2019; 8:e011045. [PMID: 30646799 PMCID: PMC6497348 DOI: 10.1161/jaha.118.011045] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 12/05/2018] [Indexed: 12/14/2022]
Abstract
Background Central arterial stiffening and increased pulsatility, with consequent cerebral hypoperfusion, may result in structural brain damage and cognitive impairment. Methods and Results We analyzed a cross-sectional sample of ARIC - NCS (Atherosclerosis Risk in Communities-Neurocognitive Study) participants (aged 67-90 years, 60% women) with measures of cognition (n=3703) and brain magnetic resonance imaging (n=1255). Central arterial hemodynamics were assessed as carotid-femoral pulse wave velocity and pressure pulsatility (central pulse pressure). We derived factor scores for cognitive domains. Brain magnetic resonance imaging using 3-Tesla scanners quantified lacunar infarcts; cerebral microbleeds; and volumes of white matter hyperintensities, total brain, and the Alzheimer disease signature region. We used logistic regression, adjusted for demographics, apolipoprotein E ɛ4, heart rate, mean arterial pressure, and select cardiovascular risk factors, to estimate the odds of lacunar infarcts or cerebral microbleeds. Linear regression, additionally adjusted for intracranial volume, estimated the difference in log-transformed volumes of white matter hyperintensities , total brain, and the Alzheimer disease signature region. We estimated the mean difference in cognitive factor scores across quartiles of carotid-femoral pulse wave velocity or central pulse pressure using linear regression. Compared with participants in the lowest carotid-femoral pulse wave velocity quartile, participants in the highest quartile of carotid-femoral pulse wave velocity had a greater burden of white matter hyperintensities ( P=0.007 for trend), smaller total brain volumes (-18.30 cm3; 95% CI , -27.54 to -9.07 cm3), and smaller Alzheimer disease signature region volumes (-1.48 cm3; 95% CI , -2.27 to -0.68 cm3). These participants also had lower scores in executive function/processing speed (β=-0.04 z score; 95% CI , -0.07 to -0.01 z score) and general cognition (β=-0.09 z score; 95% CI , -0.15 to -0.03 z score). Similar results were observed for central pulse pressure . Conclusions Central arterial hemodynamics were associated with structural brain damage and poorer cognitive performance among older adults.
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Affiliation(s)
- Priya Palta
- Department of EpidemiologyGillings School of Global Public HealthUniversity of North Carolina at Chapel HillNC
| | | | - Jingkai Wei
- Department of EpidemiologyGillings School of Global Public HealthUniversity of North Carolina at Chapel HillNC
| | - Michelle L. Meyer
- Department of Emergency MedicineUniversity of North Carolina at Chapel HillChapel HillNC
| | - Anna Kucharska‐Newton
- Department of EpidemiologyGillings School of Global Public HealthUniversity of North Carolina at Chapel HillNC
| | - Melinda C. Power
- Department of Epidemiology and BiostatisticsMilken Institute School of Public HealthGeorge Washington UniversityWashingtonDC
| | | | | | | | | | - Michael Griswold
- Department of MedicineUniversity of Mississippi Medical CenterJacksonMS
| | - Hirofumi Tanaka
- Department of Kinesiology and Health EducationUniversity of Texas at AustinTX
| | - Thomas H. Mosley
- Department of MedicineUniversity of Mississippi Medical CenterJacksonMS
| | - Gerardo Heiss
- Department of EpidemiologyGillings School of Global Public HealthUniversity of North Carolina at Chapel HillNC
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42
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Affiliation(s)
- Audrey Adji
- Department of Cardiology, St Vincent’s Clinic, Sydney, Australia
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia
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43
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Trumbore CN. Shear-induced amyloid formation of IDPs in the brain. Progress in Molecular Biology and Translational Science 2019; 166:225-309. [DOI: 10.1016/bs.pmbts.2019.05.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Stone J, Mitrofanis J, Johnstone DM, Falsini B, Bisti S, Adam P, Nuevo AB, George-Weinstein M, Mason R, Eells J. Acquired Resilience: An Evolved System of Tissue Protection in Mammals. Dose Response 2018; 16:1559325818803428. [PMID: 30627064 PMCID: PMC6311597 DOI: 10.1177/1559325818803428] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 08/22/2018] [Accepted: 08/29/2018] [Indexed: 12/11/2022] Open
Abstract
This review brings together observations on the stress-induced regulation of resilience mechanisms in body tissues. It is argued that the stresses that induce tissue resilience in mammals arise from everyday sources: sunlight, food, lack of food, hypoxia and physical stresses. At low levels, these stresses induce an organised protective response in probably all tissues; and, at some higher level, cause tissue destruction. This pattern of response to stress is well known to toxicologists, who have termed it hormesis. The phenotypes of resilience are diverse and reports of stress-induced resilience are to be found in journals of neuroscience, sports medicine, cancer, healthy ageing, dementia, parkinsonism, ophthalmology and more. This diversity makes the proposing of a general concept of induced resilience a significant task, which this review attempts. We suggest that a system of stress-induced tissue resilience has evolved to enhance the survival of animals. By analogy with acquired immunity, we term this system 'acquired resilience'. Evidence is reviewed that acquired resilience, like acquired immunity, fades with age. This fading is, we suggest, a major component of ageing. Understanding of acquired resilience may, we argue, open pathways for the maintenance of good health in the later decades of human life.
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Affiliation(s)
- Jonathan Stone
- Discipline of Physiology, Bosch Institute of Medical Research, University of Sydney, Sydney, New South Wales, Australia
| | - John Mitrofanis
- Discipline of Anatomy and Histology, Bosch Institute of Medical Research, University of Sydney, Sydney, New South Wales, Australia
| | - Daniel M. Johnstone
- Discipline of Physiology, Bosch Institute of Medical Research, University of Sydney, Sydney, New South Wales, Australia
| | - Benedetto Falsini
- Facolta’ di Medicina e Chirurgia, Fondazione Policlinico A. Gemelli, Universita’ Cattolica del S. Cuore, Rome, Italy
| | - Silvia Bisti
- Department of Biotechnical and Applied Clinical Sciences, Università degli Studi dell’Aquila, IIT Istituto Italiano di Tecnologia Genova and INBB Istituto Nazionale Biosistemi e Biostrutture, Rome, Italy
| | - Paul Adam
- School of Biological, Earth and Environmental Science, University of New South Wales, Sydney, New South Wales, Australia
| | - Arturo Bravo Nuevo
- Department of Biomedical Sciences, Philadelphia College of Osteopathic Medicine, Philadelphia, PA, USA
| | - Mindy George-Weinstein
- Department of Biomedical Sciences, Philadelphia College of Osteopathic Medicine, Philadelphia, PA, USA
| | - Rebecca Mason
- Discipline of Physiology, Bosch Institute of Medical Research, University of Sydney, Sydney, New South Wales, Australia
| | - Janis Eells
- College of Health Sciences, University of Wisconsin, Milwaukee, WI, USA
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Trumbore CN. Shear-Induced Amyloid Formation in the Brain: II. An Experimental System for Monitoring Amyloid Shear Processes and Investigating Potential Spinal Tap Problems. J Alzheimers Dis 2018; 59:543-557. [PMID: 28671126 PMCID: PMC5523842 DOI: 10.3233/jad-170259] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Liquid sheared amyloid-β (Aβ) initiates amyloid cascade reactions, producing unstable, potentially toxic oligomers. There is a need for new analytical tools with which to study these oligomers. A very small bore capillary flow system is proposed as a tool for studying the effects of liquid shear in amyloid research. This simple system consists of injecting a short cylindrical liquid sample plug containing dissolved amyloid into a liquid mobile phase flowing through an empty, very small internal diameter capillary tube. For liquid samples containing a single protein sample, under conditions in which there is laminar flow and limited sample protein molecular diffusion, chromatograms monitoring the optical protein absorbance of capillary effluent contain either one or two peaks, depending on the mobile phase flow rate. By controlling the sample diffusion times through changes in flow rate and/or capillary diameter, this tool can be used to generate aliquot samples with precise, reproducible amounts of shear for exploring the effects of variable shear on amyloid systems. The tool can be used for producing in-capillary stopped flow spectra of shear-stressed Aβ monomers as well as for kinetic studies of Aβ dimer- and oligomer-forming reactions between shear stressed Aβ monomers. Many other experiments are suggested using this experimental tool for studying the effects of shear on different Aβ and other amyloid systems, including testing for potentially serious amyloid sampling errors in spinal tap quantitative analysis. The technique has potential as both a laboratory research and a clinical tool.
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Affiliation(s)
- Conrad N Trumbore
- Department of Chemistry and Biochemistry, University of Delaware, Kennett Square, PA, USA
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46
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Avolio A, Kim MO, Adji A, Gangoda S, Avadhanam B, Tan I, Butlin M. Cerebral Haemodynamics: Effects of Systemic Arterial Pulsatile Function and Hypertension. Curr Hypertens Rep 2018; 20:20. [PMID: 29556793 DOI: 10.1007/s11906-018-0822-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
PURPOSE OF REVIEW Concepts of pulsatile arterial haemodynamics, including relationships between oscillatory blood pressure and flow in systemic arteries, arterial stiffness and wave propagation phenomena have provided basic understanding of underlying haemodynamic mechanisms associated with elevated arterial blood pressure as a major factor of cardiovascular risk, particularly the deleterious effects of isolated systolic hypertension in the elderly. This topical review assesses the effects of pulsatility of blood pressure and flow in the systemic arteries on the brain. The review builds on the emerging notion of the "pulsating brain", taking into account the high throughput of blood flow in the cerebral circulation in the presence of mechanisms involved in ensuring efficient and regulated cerebral perfusion. RECENT FINDINGS Recent studies have provided evidence of the relevance of pulsatility and hypertension in the following areas: (i) pressure and flow pulsatility and regulation of cerebral blood flow, (ii) cerebral and systemic haemodynamics, hypertension and brain pathologies (cognitive impairment, dementia, Alzheimer's disease), (iii) stroke and cerebral small vessel disease, (iv) cerebral haemodynamics and noninvasive estimation of cerebral vascular impedance, (v) cerebral and systemic pulsatile haemodynamics and intracranial pressure, (iv) response of brain endothelial cells to cyclic mechanical stretch and increase in amyloid burden. Studies to date, producing increasing epidemiological, clinical and experimental evidence, suggest a potentially significant role of systemic haemodynamic pulsatility on structure and function of the brain.
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Affiliation(s)
- Alberto Avolio
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, 2109, Australia.
| | - Mi Ok Kim
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | - Audrey Adji
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, 2109, Australia.,St. Vincent's Clinic, Victor Chang Cardiac Research Institute, University of New South Wales, Sydney, Australia
| | - Sumudu Gangoda
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | - Bhargava Avadhanam
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | - Isabella Tan
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | - Mark Butlin
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, 2109, Australia
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Thorin-Trescases N, de Montgolfier O, Pinçon A, Raignault A, Caland L, Labbé P, Thorin E. Impact of pulse pressure on cerebrovascular events leading to age-related cognitive decline. Am J Physiol Heart Circ Physiol 2018; 314:H1214-H1224. [PMID: 29451817 DOI: 10.1152/ajpheart.00637.2017] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Aging is a modern concept: human life expectancy has more than doubled in less than 150 yr in Western countries. Longer life span, however, reveals age-related diseases, including cerebrovascular diseases. The vascular system is a prime target of aging: the "wear and tear" of large elastic arteries exposed to a lifelong pulsatile pressure causes arterial stiffening by fragmentation of elastin fibers and replacement by stiffer collagen. This arterial stiffening increases in return the amplitude of the pulse pressure (PP), its wave penetrating deeper into the microcirculation of low-resistance, high-flow organs such as the brain. Several studies have associated peripheral arterial stiffness responsible for the sustained increase in PP, with brain microvascular diseases such as cerebral small vessel disease, cortical gray matter thinning, white matter atrophy, and cognitive dysfunction in older individuals and prematurely in hypertensive and diabetic patients. The rarefaction of white matter is also associated with middle cerebral artery pulsatility that is strongly dependent on PP and artery stiffness. PP and brain damage are likely associated, but the sequence of mechanistic events has not been established. Elevated PP promotes endothelial dysfunction that may slowly develop in parallel with the accumulation of proinflammatory senescent cells and oxidative stress, generating cerebrovascular damage and remodeling, as well as brain structural changes. Here, we review data suggesting that age-related increased peripheral artery stiffness may promote the penetration of a high PP to cerebral microvessels, likely causing functional, structural, metabolic, and hemodynamic alterations that could ultimately promote neuronal dysfunction and cognitive decline.
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Affiliation(s)
| | - Olivia de Montgolfier
- Montreal Heart Institute, Research Center , Montreal, Quebec , Canada.,Department of Pharmacology, Faculty of Medicine, Université de Montréal , Montreal, Quebec , Canada
| | - Anthony Pinçon
- Montreal Heart Institute, Research Center , Montreal, Quebec , Canada.,Department of Pharmacology, Faculty of Medicine, Université de Montréal , Montreal, Quebec , Canada
| | - Adeline Raignault
- Montreal Heart Institute, Research Center , Montreal, Quebec , Canada
| | - Laurie Caland
- Montreal Heart Institute, Research Center , Montreal, Quebec , Canada.,Department of Pharmacology, Faculty of Medicine, Université de Montréal , Montreal, Quebec , Canada
| | - Pauline Labbé
- Montreal Heart Institute, Research Center , Montreal, Quebec , Canada.,Department of Pharmacology, Faculty of Medicine, Université de Montréal , Montreal, Quebec , Canada
| | - Eric Thorin
- Montreal Heart Institute, Research Center , Montreal, Quebec , Canada.,Department of Pharmacology, Faculty of Medicine, Université de Montréal , Montreal, Quebec , Canada.,Department of Surgery, Faculty of Medicine, Université de Montréal , Montreal, Quebec , Canada
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48
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Kennedy G, Hardman RJ, Macpherson H, Scholey AB, Pipingas A. How Does Exercise Reduce the Rate of Age-Associated Cognitive Decline? A Review of Potential Mechanisms. J Alzheimers Dis 2018; 55:1-18. [PMID: 27636853 DOI: 10.3233/jad-160665] [Citation(s) in RCA: 111] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The rate of age-associated cognitive decline varies considerably between individuals. It is important, both on a societal and individual level, to investigate factors that underlie these differences in order to identify those which might realistically slow cognitive decline. Physical activity is one such factor with substantial support in the literature. Regular exercise can positively influence cognitive ability, reduce the rate of cognitive aging, and even reduce the risk of Alzheimer's disease (AD) and other dementias. However, while there is substantial evidence in the extant literature for the effect of exercise on cognition, the processes that mediate this relationship are less clear. This review examines cardiovascular health, production of brain derived neurotrophic factor (BDNF), insulin sensitivity, stress, and inflammation as potential pathways, via which exercise may maintain or improve cognitive functioning, and may be particularly pertinent in the context of the aging brain. A greater understanding of these mechanisms and their potential relationships with exercise and cognition will be invaluable in providing biomarkers for investigating the efficacy of differing exercise regimes on cognitive outcomes.
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Affiliation(s)
- Greg Kennedy
- Centre for Human Psychopharmacology, Swinburne University of Technology, Melbourne, VIC, Australia
| | - Roy J Hardman
- Centre for Human Psychopharmacology, Swinburne University of Technology, Melbourne, VIC, Australia
| | - Helen Macpherson
- Centre for Human Psychopharmacology, Swinburne University of Technology, Melbourne, VIC, Australia.,Centre for Physical Activity and Nutrition Research, Deakin University, Melbourne, VIC, Australia
| | - Andrew B Scholey
- Centre for Human Psychopharmacology, Swinburne University of Technology, Melbourne, VIC, Australia
| | - Andrew Pipingas
- Centre for Human Psychopharmacology, Swinburne University of Technology, Melbourne, VIC, Australia
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49
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Guo L, Vardakis JC, Lassila T, Mitolo M, Ravikumar N, Chou D, Lange M, Sarrami-Foroushani A, Tully BJ, Taylor ZA, Varma S, Venneri A, Frangi AF, Ventikos Y. Subject-specific multi-poroelastic model for exploring the risk factors associated with the early stages of Alzheimer's disease. Interface Focus 2017; 8:20170019. [PMID: 29285346 PMCID: PMC5740222 DOI: 10.1098/rsfs.2017.0019] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
There is emerging evidence suggesting that Alzheimer's disease is a vascular disorder, caused by impaired cerebral perfusion, which may be promoted by cardiovascular risk factors that are strongly influenced by lifestyle. In order to develop an understanding of the exact nature of such a hypothesis, a biomechanical understanding of the influence of lifestyle factors is pursued. An extended poroelastic model of perfused parenchymal tissue coupled with separate workflows concerning subject-specific meshes, permeability tensor maps and cerebral blood flow variability is used. The subject-specific datasets used in the modelling of this paper were collected as part of prospective data collection. Two cases were simulated involving male, non-smokers (control and mild cognitive impairment (MCI) case) during two states of activity (high and low). Results showed a marginally reduced clearance of cerebrospinal fluid (CSF)/interstitial fluid (ISF), elevated parenchymal tissue displacement and CSF/ISF accumulation and drainage in the MCI case. The peak perfusion remained at 8 mm s−1 between the two cases.
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Affiliation(s)
- Liwei Guo
- Department of Mechanical Engineering, University College London, London, UK
| | - John C Vardakis
- Department of Mechanical Engineering, University College London, London, UK
| | - Toni Lassila
- Centre for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield, UK
| | | | - Nishant Ravikumar
- Centre for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), Department of Mechanical Engineering, University of Sheffield, Sheffield, UK
| | - Dean Chou
- Institute of Biomedical Engineering and Department of Engineering Science, University of Oxford, Oxford, UK
| | - Matthias Lange
- Centre for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield, UK
| | - Ali Sarrami-Foroushani
- Centre for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield, UK
| | - Brett J Tully
- Children's Medical Research Institute and School of Medical Sciences, Sydney Medical School, The University of Sydney, Westmead, Australia
| | - Zeike A Taylor
- Centre for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), Department of Mechanical Engineering, University of Sheffield, Sheffield, UK
| | - Susheel Varma
- Centre for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield, UK
| | - Annalena Venneri
- Department of Neuroscience, Medical School, University of Sheffield, Sheffield, UK
| | - Alejandro F Frangi
- Centre for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield, UK
| | - Yiannis Ventikos
- Department of Mechanical Engineering, University College London, London, UK
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Kim MO, Li Y, Wei F, Wang J, O’rourke MF, Adji A, Avolio AP. Normal cerebral vascular pulsations in humans: changes with age and implications for microvascular disease. J Hypertens 2017; 35:2245-56. [DOI: 10.1097/hjh.0000000000001459] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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