1
|
Ercolano E, Bencivenga L, Palaia ME, Carbone G, Scognamiglio F, Rengo G, Femminella GD. Intricate relationship between obstructive sleep apnea and dementia in older adults. GeroScience 2024; 46:99-111. [PMID: 37814196 PMCID: PMC10828345 DOI: 10.1007/s11357-023-00958-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 09/21/2023] [Indexed: 10/11/2023] Open
Abstract
Numerous evidence reports direct correlation between cognitive impairment, Alzheimer's disease and sleep disorders, in particular obstructive sleep apnea. Both obstructive sleep apnea and Alzheimer's disease are highly prevalent conditions whose incidence increases with age. Several studies demonstrate how sleep-disordered breathing may lead to poor cognition, even though the underlying mechanisms of this association remain partially unclear. According to the most recent studies, obstructive sleep apnea may be considered a modifiable risk factor for cognitive dysfunction. In the present review, the authors aim to integrate recent research examining obstructive sleep apnea and Alzheimer's disease biomarkers, also focusing on the mechanisms that support this correlation, including but not limited to the role of hypoxia and cardiovascular risk. Moreover, the potential favourable effect of obstructive sleep apnea therapy on cognitive function is discussed, to evaluate the benefits deriving from appropriate treatment of sleep-disordered breathing on cognition.
Collapse
Affiliation(s)
- Erica Ercolano
- Department of Translational Medical Sciences, University of Naples "Federico II", Via Pansini, 5, Naples, Italy
| | - Leonardo Bencivenga
- Department of Translational Medical Sciences, University of Naples "Federico II", Via Pansini, 5, Naples, Italy
| | - Maria Emiliana Palaia
- Department of Translational Medical Sciences, University of Naples "Federico II", Via Pansini, 5, Naples, Italy
| | - Giovanni Carbone
- Department of Translational Medical Sciences, University of Naples "Federico II", Via Pansini, 5, Naples, Italy
| | - Francesco Scognamiglio
- Department of Translational Medical Sciences, University of Naples "Federico II", Via Pansini, 5, Naples, Italy
| | - Giuseppe Rengo
- Department of Translational Medical Sciences, University of Naples "Federico II", Via Pansini, 5, Naples, Italy
- Istituti Clinici Scientifici ICS Maugeri - S.P.A. - Istituti Di Ricovero E Cura a Carattere Scientifico (IRCCS) Istituto Scientifico Di Telese Terme, Telese, Italy
| | - Grazia Daniela Femminella
- Department of Translational Medical Sciences, University of Naples "Federico II", Via Pansini, 5, Naples, Italy.
- Department of Brain Sciences, Imperial College London, London, UK.
| |
Collapse
|
2
|
Rastogi R, Morgan BJ, Badr MS, Chowdhuri S. Hypercapnia-induced vasodilation in the cerebral circulation is reduced in older adults with sleep-disordered breathing. J Appl Physiol (1985) 2022; 132:14-23. [PMID: 34709067 PMCID: PMC8721948 DOI: 10.1152/japplphysiol.00347.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The prevalence of sleep-disordered breathing (SDB) is higher in older adults compared with younger individuals. The increased propensity for ventilatory control instability in older adults may contribute to the increased prevalence of central apneas. Reductions in the cerebral vascular response to CO2 may exacerbate ventilatory overshoots and undershoots during sleep. Thus, we hypothesized that hypercapnia-induced cerebral vasodilation (HCVD) will be reduced in older compared with younger adults. In 11 older and 10 younger adults with SDB, blood flow velocity in the middle cerebral artery (MCAV) was measured using Doppler transcranial ultrasonography during multiple steady-state hyperoxic hypercapnic breathing trials while awake, interspersed with room air breathing. Changes in ventilation, MCAV, and mean arterial pressure (MAP) via finger plethysmography during the trials were compared with baseline eupneic values. For each hyperoxic hypercapnic trial, the change (Δ) in MCAV for a corresponding change in end-tidal CO2 and the HCVD or the change in cerebral vascular conductance (MCAV divided by MAP) for a corresponding change in end-tidal CO2 was determined. The hypercapnic ventilatory response was similar between the age groups, as was ΔMCAV/Δ[Formula: see text]. However, compared with young, older adults had a significantly smaller HCVD (1.3 ± 0.7 vs. 2.1 ± 0.6 units/mmHg, P = 0.004). Multivariable analyses demonstrated that age and nadir oxygen saturation during nocturnal polysomnography were significant predictors of HCVD. Thus, our data indicate that older age and SDB-related hypoxia are associated with diminished HCVD. We hypothesize that this impairment in vascular function may contribute to breathing instability during sleep in these individuals.NEW & NOTEWORTHY This study demonstrates, for the first time, in individuals with sleep-disordered breathing (SDB) that aging is associated with decreased hypercapnia-induced cerebral vasodilation (HCVD). In addition to advanced age, the magnitude of nocturnal oxygen desaturation due to SDB is an equal independent predictor of HCVD.
Collapse
Affiliation(s)
- R. Rastogi
- 1Medical Service, Sleep Medicine Section, John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan,2Division of Pulmonary/Critical Care and Sleep Medicine, Department of Medicine, Wayne State University School of Medicine, Detroit, Michigan
| | - B. J. Morgan
- 3Department of Orthopedics and Rehabilitation, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - M. S. Badr
- 1Medical Service, Sleep Medicine Section, John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan,2Division of Pulmonary/Critical Care and Sleep Medicine, Department of Medicine, Wayne State University School of Medicine, Detroit, Michigan
| | - S. Chowdhuri
- 1Medical Service, Sleep Medicine Section, John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan,2Division of Pulmonary/Critical Care and Sleep Medicine, Department of Medicine, Wayne State University School of Medicine, Detroit, Michigan
| |
Collapse
|
3
|
Schaeffer S, Iadecola C. Revisiting the neurovascular unit. Nat Neurosci 2021; 24:1198-1209. [PMID: 34354283 PMCID: PMC9462551 DOI: 10.1038/s41593-021-00904-7] [Citation(s) in RCA: 245] [Impact Index Per Article: 81.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 06/30/2021] [Indexed: 02/06/2023]
Abstract
The brain is supplied by an elaborate vascular network that originates extracranially and reaches deep into the brain. The concept of the neurovascular unit provides a useful framework to investigate how neuronal signals regulate nearby microvessels to support the metabolic needs of the brain, but it does not consider the role of larger cerebral arteries and systemic vasoactive signals. Furthermore, the recently emerged molecular heterogeneity of cerebrovascular cells indicates that there is no prototypical neurovascular unit replicated at all levels of the vascular network. Here, we examine the cellular and molecular diversity of the cerebrovascular tree and the relative contribution of systemic and brain-intrinsic factors to neurovascular function. Evidence supports the concept of a 'neurovascular complex' composed of segmentally diverse functional modules that implement coordinated vascular responses to central and peripheral signals to maintain homeostasis of the brain. This concept has major implications for neurovascular regulation in health and disease and for brain imaging.
Collapse
|
4
|
Bubu OM, Andrade AG, Umasabor-Bubu OQ, Hogan MM, Turner AD, de Leon MJ, Ogedegbe G, Ayappa I, Jean-Louis G G, Jackson ML, Varga AW, Osorio RS. Obstructive sleep apnea, cognition and Alzheimer's disease: A systematic review integrating three decades of multidisciplinary research. Sleep Med Rev 2019; 50:101250. [PMID: 31881487 DOI: 10.1016/j.smrv.2019.101250] [Citation(s) in RCA: 190] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 11/25/2019] [Accepted: 11/28/2019] [Indexed: 12/29/2022]
Abstract
Increasing evidence links cognitive-decline and Alzheimer's disease (AD) to various sleep disorders, including obstructive sleep apnea (OSA). With increasing age, there are substantial differences in OSA's prevalence, associated comorbidities and phenotypic presentation. An important question for sleep and AD researchers is whether OSA's heterogeneity results in varying cognitive-outcomes in older-adults compared to middle-aged adults. In this review, we systematically integrated research examining OSA and cognition, mild cognitive-impairment (MCI) and AD/AD biomarkers; including the effects of continuous positive airway pressure (CPAP) treatment, particularly focusing on characterizing the heterogeneity of OSA and its cognitive-outcomes. Broadly, in middle-aged adults, OSA is often associated with mild impairment in attention, memory and executive function. In older-adults, OSA is not associated with any particular pattern of cognitive-impairment at cross-section; however, OSA is associated with the development of MCI or AD with symptomatic patients who have a higher likelihood of associated disturbed sleep/cognitive-impairment driving these findings. CPAP treatment may be effective in improving cognition in OSA patients with AD. Recent trends demonstrate links between OSA and AD-biomarkers of neurodegeneration across all age-groups. These distinct patterns provide the foundation for envisioning better characterization of OSA and the need for more sensitive/novel sleep-dependent cognitive assessments to assess OSA-related cognitive-impairment.
Collapse
Affiliation(s)
- Omonigho M Bubu
- Center for Brain Health, Department of Psychiatry, NYU Langone Medical Center, New York, NY, USA; Department of Population Health, New York University School of Medicine, Center for Healthful Behavior Change, New York, USA; Department of Epidemiology and Biostatistics, College of Public Health, University of South Florida, Tampa, FL, USA; Department of Applied Health Sciences, Wheaton College, Wheaton, IL, USA.
| | - Andreia G Andrade
- Center for Brain Health, Department of Psychiatry, NYU Langone Medical Center, New York, NY, USA
| | | | - Megan M Hogan
- Department of Applied Health Sciences, Wheaton College, Wheaton, IL, USA
| | - Arlener D Turner
- Center for Brain Health, Department of Psychiatry, NYU Langone Medical Center, New York, NY, USA; Department of Human Services and Psychology, National Louis University, Chicago, IL, USA
| | - Mony J de Leon
- Center for Brain Health, Department of Psychiatry, NYU Langone Medical Center, New York, NY, USA; Department of Radiology, Weill Cornell Medicine, New York, NY 10065, USA
| | - Gbenga Ogedegbe
- Department of Population Health, New York University School of Medicine, Center for Healthful Behavior Change, New York, USA
| | - Indu Ayappa
- Division of Pulmonary, Critical Care and Sleep Medicine at the Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Girardin Jean-Louis G
- Center for Brain Health, Department of Psychiatry, NYU Langone Medical Center, New York, NY, USA; Department of Population Health, New York University School of Medicine, Center for Healthful Behavior Change, New York, USA
| | - Melinda L Jackson
- Institute for Breathing and Sleep, Austin Health, Heidelberg, Victoria, Australia; School of Health & Biomedical Sciences, RMIT University, Bundoora, Victoria, Australia
| | - Andrew W Varga
- Division of Pulmonary, Critical Care and Sleep Medicine at the Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Ricardo S Osorio
- Center for Brain Health, Department of Psychiatry, NYU Langone Medical Center, New York, NY, USA.
| |
Collapse
|
5
|
Daulatzai MA. Cerebral hypoperfusion and glucose hypometabolism: Key pathophysiological modulators promote neurodegeneration, cognitive impairment, and Alzheimer's disease. J Neurosci Res 2016; 95:943-972. [PMID: 27350397 DOI: 10.1002/jnr.23777] [Citation(s) in RCA: 274] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 05/06/2016] [Accepted: 05/07/2016] [Indexed: 02/06/2023]
Abstract
Aging, hypertension, diabetes, hypoxia/obstructive sleep apnea (OSA), obesity, vitamin B12/folate deficiency, depression, and traumatic brain injury synergistically promote diverse pathological mechanisms including cerebral hypoperfusion and glucose hypometabolism. These risk factors trigger neuroinflammation and oxidative-nitrosative stress that in turn decrease nitric oxide and enhance endothelin, Amyloid-β deposition, cerebral amyloid angiopathy, and blood-brain barrier disruption. Proinflammatory cytokines, endothelin-1, and oxidative-nitrosative stress trigger several pathological feedforward and feedback loops. These upstream factors persist in the brain for decades, upregulating amyloid and tau, before the cognitive decline. These cascades lead to neuronal Ca2+ increase, neurodegeneration, cognitive/memory decline, and Alzheimer's disease (AD). However, strategies are available to attenuate cerebral hypoperfusion and glucose hypometabolism and ameliorate cognitive decline. AD is the leading cause of dementia among the elderly. There is significant evidence that pathways involving inflammation and oxidative-nitrosative stress (ONS) play a key pathophysiological role in promoting cognitive dysfunction. Aging and several comorbid conditions mentioned above promote diverse pathologies. These include inflammation, ONS, hypoperfusion, and hypometabolism in the brain. In AD, chronic cerebral hypoperfusion and glucose hypometabolism precede decades before the cognitive decline. These comorbid disease conditions may share and synergistically activate these pathophysiological pathways. Inflammation upregulates cerebrovascular pathology through proinflammatory cytokines, endothelin-1, and nitric oxide (NO). Inflammation-triggered ONS promotes long-term damage involving fatty acids, proteins, DNA, and mitochondria; these amplify and perpetuate several feedforward and feedback pathological loops. The latter includes dysfunctional energy metabolism (compromised mitochondrial ATP production), amyloid-β generation, endothelial dysfunction, and blood-brain-barrier disruption. These lead to decreased cerebral blood flow and chronic cerebral hypoperfusion- that would modulate metabolic dysfunction and neurodegeneration. In essence, hypoperfusion deprives the brain from its two paramount trophic substances, viz., oxygen and nutrients. Consequently, the brain suffers from synaptic dysfunction and neuronal degeneration/loss, leading to both gray and white matter atrophy, cognitive dysfunction, and AD. This Review underscores the importance of treating the above-mentioned comorbid disease conditions to attenuate inflammation and ONS and ameliorate decreased cerebral blood flow and hypometabolism. Additionally, several strategies are described here to control chronic hypoperfusion of the brain and enhance cognition. © 2016 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Mak Adam Daulatzai
- Sleep Disorders Group, EEE Dept/MSE, The University of Melbourne, Parkville, Victoria, Australia
| |
Collapse
|
6
|
Alexandre F, Heraud N, Sanchez AM, Tremey E, Oliver N, Guerin P, Varray A. Brain Damage and Motor Cortex Impairment in Chronic Obstructive Pulmonary Disease: Implication of Nonrapid Eye Movement Sleep Desaturation. Sleep 2016; 39:327-35. [PMID: 26446126 PMCID: PMC4712404 DOI: 10.5665/sleep.5438] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 09/05/2015] [Indexed: 12/14/2022] Open
Abstract
STUDY OBJECTIVES Nonrapid eye movement (NREM) sleep desaturation may cause neuronal damage due to the withdrawal of cerebrovascular reactivity. The current study (1) assessed the prevalence of NREM sleep desaturation in nonhypoxemic patients with chronic obstructive pulmonary disease (COPD) and (2) compared a biological marker of cerebral lesion and neuromuscular function in patients with and without NREM sleep desaturation. METHODS One hundred fifteen patients with COPD (Global Initiative for Chronic Obstructive Lung Disease [GOLD] grades 2 and 3), resting PaO2 of 60-80 mmHg, aged between 40 and 80 y, and without sleep apnea (apnea-hypopnea index < 15) had polysomnographic sleep recordings. In addition, twenty-nine patients (substudy) were assessed i) for brain impairment by serum S100B (biological marker of cerebral lesion), and ii) for neuromuscular function via motor cortex activation and excitability and maximal voluntary quadriceps strength measurement. RESULTS A total of 51.3% patients (n = 59) had NREM sleep desaturation (NREMDes). Serum S100B was higher in the NREMDes patients of the substudy (n = 14): 45.1 [Q1: 37.7, Q3: 62.8] versus 32.9 [Q1: 25.7, Q3: 39.5] pg.ml(-1) (P = 0.028). Motor cortex activation and excitability were lower in NREMDes patients (both P = 0.03), but muscle strength was comparable between groups (P = 0.58). CONCLUSIONS Over half the nonhypoxemic COPD patients exhibited NREM sleep desaturation associated with higher values of the cerebral lesion biomarker and lower neural drive reaching the quadriceps during maximal voluntary contraction. The lack of muscle strength differences between groups suggests a compensatory mechanism(s). Altogether, the results are consistent with an involvement of NREM sleep desaturation in COPD brain impairment. CLINICAL TRIAL REGISTRATION The study was registered at www.clinicaltrials.gov as NCT01679782.
Collapse
Affiliation(s)
- Francois Alexandre
- Movement To Health Laboratory, Euromov, University of Montpellier, Montpellier, France
- Clinique du Souffle La Vallonie, Fontalvie, Lodève, France
| | - Nelly Heraud
- Clinique du Souffle La Vallonie, Fontalvie, Lodève, France
- Clinique du Souffle Les Clarines, Fontalvie, Riom-es-Montagnes, France
| | - Anthony M.J. Sanchez
- UMR866 Dynamique Musculaire et Métabolisme, INRA, University of Montpellier, Montpellier, France
- Laboratoire Performance Santé Altitude, EA 4604, University of Perpignan Via Domitia, Font-Romeu, France
| | - Emilie Tremey
- Clinique du Souffle La Vallonie, Fontalvie, Lodève, France
- Clinique du Souffle Les Clarines, Fontalvie, Riom-es-Montagnes, France
| | - Nicolas Oliver
- Clinique du Souffle La Vallonie, Fontalvie, Lodève, France
| | - Philippe Guerin
- Clinique du Souffle Les Clarines, Fontalvie, Riom-es-Montagnes, France
| | - Alain Varray
- Movement To Health Laboratory, Euromov, University of Montpellier, Montpellier, France
| |
Collapse
|
7
|
Daulatzai MA. Evidence of neurodegeneration in obstructive sleep apnea: Relationship between obstructive sleep apnea and cognitive dysfunction in the elderly. J Neurosci Res 2015; 93:1778-94. [DOI: 10.1002/jnr.23634] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 08/02/2015] [Accepted: 08/04/2015] [Indexed: 02/06/2023]
Affiliation(s)
- Mak Adam Daulatzai
- Sleep Disorders Group, EEE/Melbourne School of Engineering, The University of Melbourne; Parkville Victoria Australia
| |
Collapse
|
8
|
Patyar S, Patyar RR. Correlation between Sleep Duration and Risk of Stroke. J Stroke Cerebrovasc Dis 2015; 24:905-11. [DOI: 10.1016/j.jstrokecerebrovasdis.2014.12.038] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 12/27/2014] [Accepted: 12/31/2014] [Indexed: 10/23/2022] Open
|
9
|
Alexandre F, Heraud N, Varray A. Is nocturnal desaturation a trigger for neuronal damage in chronic obstructive pulmonary disease? Med Hypotheses 2015; 84:25-30. [DOI: 10.1016/j.mehy.2014.11.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 11/03/2014] [Accepted: 11/09/2014] [Indexed: 01/26/2023]
|
10
|
Global brain blood-oxygen level responses to autonomic challenges in obstructive sleep apnea. PLoS One 2014; 9:e105261. [PMID: 25166862 PMCID: PMC4148259 DOI: 10.1371/journal.pone.0105261] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Accepted: 07/22/2014] [Indexed: 01/18/2023] Open
Abstract
Obstructive sleep apnea (OSA) is accompanied by brain injury, perhaps resulting from apnea-related hypoxia or periods of impaired cerebral perfusion. Perfusion changes can be determined indirectly by evaluation of cerebral blood volume and oxygenation alterations, which can be measured rapidly and non-invasively with the global blood oxygen level dependent (BOLD) signal, a magnetic resonance imaging procedure. We assessed acute BOLD responses in OSA subjects to pressor challenges that elicit cerebral blood flow changes, using a two-group comparative design with healthy subjects as a reference. We separately assessed female and male patterns, since OSA characteristics and brain injury differ between sexes. We studied 94 subjects, 37 with newly-diagnosed, untreated OSA (6 female (age mean ± std: 52.1±8.1 yrs; apnea/hypopnea index [AHI]: 27.7±15.6 events/hr and 31 male 54.3±8.4 yrs; AHI: 37.4±19.6 events/hr), and 20 female (age 50.5±8.1 yrs) and 37 male (age 45.6±9.2 yrs) healthy control subjects. We measured brain BOLD responses every 2 s while subjects underwent cold pressor, hand grip, and Valsalva maneuver challenges. The global BOLD signal rapidly changed after the first 2 s of each challenge, and differed in magnitude between groups to two challenges (cold pressor, hand grip), but not to the Valsalva maneuver (repeated measures ANOVA, p<0.05). OSA females showed greater differences from males in response magnitude and pattern, relative to healthy counterparts. Cold pressor BOLD signal increases (mean ± adjusted standard error) at the 8 s peak were: OSA 0.14±0.08% vs. Control 0.31±0.06%, and hand grip at 6 s were: OSA 0.08±0.03% vs. Control at 0.30±0.02%. These findings, indicative of reduced cerebral blood flow changes to autonomic challenges in OSA, complement earlier reports of altered resting blood flow and reduced cerebral artery responsiveness. Females are more affected than males, an outcome which may contribute to the sex-specific brain injury in the syndrome.
Collapse
|
11
|
Death by a thousand cuts in Alzheimer's disease: hypoxia--the prodrome. Neurotox Res 2013; 24:216-43. [PMID: 23400634 DOI: 10.1007/s12640-013-9379-2] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 01/10/2013] [Accepted: 01/21/2013] [Indexed: 12/30/2022]
Abstract
A wide range of clinical consequences may be associated with obstructive sleep apnea (OSA) including systemic hypertension, cardiovascular disease, pulmonary hypertension, congestive heart failure, cerebrovascular disease, glucose intolerance, impotence, gastroesophageal reflux, and obesity, to name a few. Despite this, 82 % of men and 93 % of women with OSA remain undiagnosed. OSA affects many body systems, and induces major alterations in metabolic, autonomic, and cerebral functions. Typically, OSA is characterized by recurrent chronic intermittent hypoxia (CIH), hypercapnia, hypoventilation, sleep fragmentation, peripheral and central inflammation, cerebral hypoperfusion, and cerebral glucose hypometabolism. Upregulation of oxidative stress in OSA plays an important pathogenic role in the milieu of hypoxia-induced cerebral and cardiovascular dysfunctions. Strong evidence underscores that cerebral amyloidogenesis and tau phosphorylation--two cardinal features of Alzheimer's disease (AD), are triggered by hypoxia. Mice subjected to hypoxic conditions unambiguously demonstrated upregulation in cerebral amyloid plaque formation and tau phosphorylation, as well as memory deficit. Hypoxia triggers neuronal degeneration and axonal dysfunction in both cortex and brainstem. Consequently, neurocognitive impairment in apneic/hypoxic patients is attributable to a complex interplay between CIH and stimulation of several pathological trajectories. The framework presented here helps delineate the emergence and progression of cognitive decline, and may yield insight into AD neuropathogenesis. The global impact of CIH should provide a strong rationale for treating OSA and snoring clinically, in order to ameliorate neurocognitive impairment in aged/AD patients.
Collapse
|
12
|
|
13
|
Quintessential Risk Factors: Their Role in Promoting Cognitive Dysfunction and Alzheimer’s Disease. Neurochem Res 2012; 37:2627-58. [DOI: 10.1007/s11064-012-0854-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Accepted: 07/21/2012] [Indexed: 12/13/2022]
|
14
|
Pathogenesis of cognitive dysfunction in patients with obstructive sleep apnea: a hypothesis with emphasis on the nucleus tractus solitarius. SLEEP DISORDERS 2012; 2012:251096. [PMID: 23470865 PMCID: PMC3581091 DOI: 10.1155/2012/251096] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Revised: 12/13/2011] [Accepted: 12/22/2011] [Indexed: 02/06/2023]
Abstract
OSA is characterized by the quintessential triad of intermittent apnea, hypoxia, and hypoxemia due to pharyngeal collapse. This paper highlights the upstream mechanisms that may trigger cognitive decline in OSA. Three interrelated steps underpin cognitive dysfunction in OSA patients. First, several risk factors upregulate peripheral inflammation; these crucial factors promote neuroinflammation, cerebrovascular endothelial dysfunction, and oxidative stress in OSA. Secondly, the neuroinflammation exerts negative impact globally on the CNS, and thirdly, important foci in the neocortex and brainstem are rendered inflamed and dysfunctional. A strong link is known to exist between neuroinflammation and neurodegeneration. A unique perspective delineated here underscores the importance of dysfunctional brainstem nuclei in etiopathogenesis of cognitive decline in OSA patients. Nucleus tractus solitarius (NTS) is the central integration hub for afferents from upper airway (somatosensory/gustatory), respiratory, gastrointestinal, cardiovascular (baroreceptor and chemoreceptor) and other systems. The NTS has an essential role in sympathetic and parasympathetic systems also; it projects to most key brain regions and modulates numerous physiological functions. Inflamed and dysfunctional NTS and other key brainstem nuclei may play a pivotal role in triggering memory and cognitive dysfunction in OSA. Attenuation of upstream factors and amelioration of the NTS dysfunction remain important challenges.
Collapse
|
15
|
Dysfunctional nucleus tractus solitarius: its crucial role in promoting neuropathogenetic cascade of Alzheimer's dementia--a novel hypothesis. Neurochem Res 2012; 37:846-68. [PMID: 22219130 DOI: 10.1007/s11064-011-0680-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 11/16/2011] [Accepted: 12/15/2011] [Indexed: 12/22/2022]
Abstract
The pathophysiological mechanism(s) underlying Alzheimer's disease (AD) still remain unclear, and no disease-modifying or prophylactic therapies are currently available. Unraveling the fundamental neuropathogenesis of AD is an important challenge. Several studies on AD have suggested lesions in a number of CNS areas including the basal forebrain, hippocampus, entorhinal cortex, amygdale/insula, and the locus coeruleus. However, plausible unifying studies on the upstream factors that involve these heterogeneous regions and herald the onset of AD pathogenesis are not available. The current article presents a novel nucleus tractus solitarius (NTS) vector hypothesis that underpins several disparate biological mechanisms and neural circuits, and identifies relevant hallmarks of major presumptive causative factor(s) linked to the NTS, in older/aging individuals. Aging, obesity, infection, sleep apnea, smoking, neuropsychological states, and hypothermia-all activate inflammatory cytokines and oxidative stress. The synergistic impact of systemic proinflammatory mediators activates microglia and promotes neuroinflammation. Acutely, the innate immune response is protective defending against pathogens/toxins; however, when chronic, it causes neuroinflammation and neuronal dysfunction, particularly in brainstem and neocortex. The NTS in the brainstem is an essential multiple signaling hub, and an extremely important central integration site of baroreceptor, chemoreceptor, and a multitude of sensory afferents from gustatory, gastrointestinal, cardiac, pulmonary, and upper airway systems. Owing to persistent neuroinflammation, the dysfunctional NTS exerts deleterious impact on nucleus ambiguus, dorsal motor nucleus of vagus, hypoglossal, parabrachial, locus coeruleus and many key nuclei in the brainstem, and the hippocampus, entorhinal cortex, prefrontal cortex, amygdala, insula, and basal forebrain in the neocortex. The neuronal and synaptic dysfunction emanating from the inflamed NTS may affect its interconnected pathways impacting almost the entire CNS--which is already primed by neuroinflammation, thus promoting cognitive and neuropsychiatric symptoms. The upstream factors discussed here may underpin the neuropathopgenesis of AD. AD pathology is multifactorial; the current perspective underscores the value of attenuating disparate upstream factors--in conjunction with anticholinesterase, anti-inflammatory, immunosuppressive, and anti-oxidant pharmacotherapy. Amelioration of the NTS pathology may be of central importance in countering the neuropathological cascade of AD. The NTS, therefore, may be a potential target of novel therapeutic strategies.
Collapse
|
16
|
Nobili L, Proserpio P, Rubboli G, Montano N, Didato G, Tassinari CA. Sudden unexpected death in epilepsy (SUDEP) and sleep. Sleep Med Rev 2011; 15:237-46. [DOI: 10.1016/j.smrv.2010.07.006] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Revised: 07/12/2010] [Accepted: 07/16/2010] [Indexed: 11/30/2022]
|
17
|
Kilduff TS, Cauli B, Gerashchenko D. Activation of cortical interneurons during sleep: an anatomical link to homeostatic sleep regulation? Trends Neurosci 2010; 34:10-9. [PMID: 21030095 DOI: 10.1016/j.tins.2010.09.005] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2010] [Revised: 08/19/2010] [Accepted: 09/23/2010] [Indexed: 10/18/2022]
Abstract
Although slow wave activity in the EEG has been linked to homeostatic sleep regulation, the neurobiological substrate of sleep homeostasis is not well understood. Whereas cortical neurons typically exhibit reduced discharge rates during slow wave sleep (SWS), a subpopulation of GABAergic interneurons, which express the enzyme neuronal nitric oxide synthase (nNOS), has recently been found to be activated during SWS. The extent of activation of these nNOS neurons is proportional to homeostatic sleep 'drive'. These cells are an exception among cortical interneurons in that they are projection neurons. We propose that cortical nNOS neurons are positioned to influence neuronal activity across widespread brain areas. They could thus provide a long-sought anatomical link for understanding homeostatic sleep regulation.
Collapse
Affiliation(s)
- Thomas S Kilduff
- Center for Neuroscience, Biosciences Division, SRI International, Menlo Park, CA 94025, USA.
| | | | | |
Collapse
|
18
|
Carlson BW, Neelon VJ, Carlson JR, Hartman M, Dogra S. Cerebrovascular disease and patterns of cerebral oxygenation during sleep in elders. Biol Res Nurs 2009; 10:307-17. [PMID: 19144652 PMCID: PMC3377477 DOI: 10.1177/1099800408330396] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
PURPOSE The aim of this descriptive exploratory study was to describe patterns of cerebral oxygen reserves during sleep and their association with cerebrovascular risk factors in elders. METHOD Participants--115 elders, age 70+ years--were monitored overnight using standard polysomnography. Measures included arterial oxyhemoglobin (SaO2) and regional measures of percentage of cerebral oxyhemoglobin saturation (rcSO2) via cerebral oximetry. Participants were classified based on the magnitude of change in rcSO2 from resting baseline to the end of the first nonrapid-eye-movement (NREM) period. One-way ANOVA and Chi-square were used to test group differences in SaO2 and the prevalence of cerebrovascular risk factors. FINDINGS 20 participants (Group 1) experienced an increase in rcSO2 during sleep along with sleeping rcSO2 levels >or= 55%; 95 participants experienced a decline in rcSO2; 72 participants (Group 2) had sleeping rcSO2 levels >or= 55%; and 23 participants had sleeping rcSO2 levels <55% (Group 3). Although all three groups had equivalent declines in SaO2 levels during sleep, Group 3 had more cardiovascular comorbidity than Groups 1 and 2. CONCLUSIONS Although SaO2 levels decline in most people during sleep, compensatory vascular responses to these drops in SaO2 are important for preventing rcSO2 from falling during sleep. Those entering sleep with lower baseline rcSO2 levels and those with greater declines in cerebral oxygenation during sleep may have greater cardiovascular burden and be at greater risk for stroke and other forms of disabling cerebrovascular disease.
Collapse
Affiliation(s)
- Barbara Waag Carlson
- Biobehavioral Laboratory, The University of North Carolina at Chapel Hill, CB# 7460, Carrington Hall, Chapel Hill, NC 27599. PH: (919) 966-7598, FAX: (919) 843-9900,
| | - Virginia J. Neelon
- Biobehavioral Laboratory, The University of North Carolina at Chapel Hill,
| | - John R. Carlson
- School of Nursing, The University of North Carolina at Chapel Hill,
| | - Marilyn Hartman
- Institute on Aging, The University of North Carolina at Chapel Hill,
| | - Sunil Dogra
- Department of Anesthesiology and Pain Management, School of Medicine, The University of North Carolina at Chapel Hill,
| |
Collapse
|
19
|
Carlson BW, Neelon VJ, Carlson JR, Hartman M, Dogra S. Exploratory analysis of cerebral oxygen reserves during sleep onset in older and younger adults. J Am Geriatr Soc 2008; 56:914-9. [PMID: 18384588 PMCID: PMC3377447 DOI: 10.1111/j.1532-5415.2008.01672.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVES To explore differences in cerebral oxygen reserves during sleep in old and young adults. DESIGN Descriptive cross-sectional study. SETTING General clinical research center. PARTICIPANTS Nine old (aged 65-84) and 10 young (aged 21-39) adults. MEASUREMENTS Subjects were monitored during the first nightly sleep cycle using standard polysomnography, including measures of arterial oxyhemoglobin saturation (SaO(2)). Changes in regional cerebral oxyhemoglobin saturation (rcSO(2)) were used to estimate cerebral oxygen reserves. General linear models were used to test group differences in the change in SaO(2) and rcSO(2) during sleep. RESULTS Older subjects had lower SaO(2) than young subjects before sleep (baseline) (F((1,18))=5.1, P=.04) and during sleep (F((1,18))=10.7, P=.01). During sleep, half of the older subjects and none of the younger ones had SaO(2) values below 95%. In addition, the older subjects had more periods of oxygen desaturation (drops in SaO(2) > or = 4%) (chi-square=24.3, P=.01) and lower SaO(2) levels during desaturation (F((1,18))=11.1, P<.01). Although baseline values were similar, rcSO(2) decreased during sleep 2.1% in older subjects (F((1,8))=3.8, P=.05) but increased 2.1% during sleep in younger subjects (F((1,9))=4.6, P=.04). When the older subjects awakened from sleep, rcSO(2), but not SaO(2), returned to baseline; both returned to baseline in younger subjects. CONCLUSION This exploratory analysis generated the hypothesis that lower SaO(2), combined with declines in regional blood flow, contributes to decline in cerebral oxygen reserves during sleep in older subjects. Further study will assess the effects of factors (e.g., medical conditions, subclinical disorders, and sleep architecture) that might account for these differences.
Collapse
Affiliation(s)
- Barbara W. Carlson
- Associate Professor, School of Nursing, The University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Virginia J. Neelon
- Associate Professor, School of Nursing, The University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - John R. Carlson
- Research Associate Professor, School of Nursing, The University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Marilyn Hartman
- Research Associate Professor, Department of Psychology, The University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Sunil Dogra
- Clinical Associate Professor, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC
| |
Collapse
|
20
|
Corfield DR. Cerebrovascular function: changes in health and disease. Exp Physiol 2008; 93:115. [PMID: 18165433 DOI: 10.1113/expphysiol.2007.038539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Douglas R Corfield
- Institute of Science and Technology in Medicine, Keele University, Staffordshire ST5 5BG, UK.
| |
Collapse
|
21
|
Brugniaux JV, Hodges ANH, Hanly PJ, Poulin MJ. Cerebrovascular responses to altitude. Respir Physiol Neurobiol 2007; 158:212-23. [PMID: 17544954 DOI: 10.1016/j.resp.2007.04.008] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2007] [Revised: 04/17/2007] [Accepted: 04/19/2007] [Indexed: 10/23/2022]
Abstract
The regulation of cerebral blood flow (CBF) is a complex process that is altered significantly with altitude exposure. Acute exposure produces a marked increase in CBF, in proportion to the severity of the hypoxia and mitigated by hyperventilation-induced hypocapnia when CO(2) is uncontrolled. A number of mediators contribute to the hypoxia-induced cerebral vasodilation, including adenosine, potassium channels, substance P, prostaglandins, and NO. Upon acclimatization to altitude, CBF returns towards normal sea-level values in subsequent days and weeks, mediated by a progressive increase in PO2, first through hyperventilation followed by erythropoiesis. With long-term altitude exposure, a number of mechanisms play a role in regulating CBF, including acid-base balance, hematological modifications, and angiogenesis. Finally, several cerebrovascular disorders are associated with altitude exposure. Existing gaps in our knowledge of CBF and altitude, and areas of future investigation include effects of longer exposures, intermittent hypoxia, and gender differences in the CBF responses to altitude.
Collapse
Affiliation(s)
- Julien V Brugniaux
- Department of Physiology & Biophysics, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | | | | | | |
Collapse
|
22
|
Abstract
After defining the current approach to measuring the hypoxic ventilatory response this paper explains why this method is not appropriate for comparisons between individuals or conditions, and does not adequately measure the parameters of the peripheral chemoreflex. A measurement regime is therefore proposed that incorporates three procedures. The first procedure measures the peripheral chemoreflex responsiveness to both hypoxia and CO(2) in terms of hypoxia's effects on the sensitivity and ventilatory recruitment threshold of the peripheral chemoreflex response to CO(2). The second and third procedures employ current methods for measuring the isocapnic and poikilocapnic ventilatory responses to hypoxia, respectively, over a period of 20 min. The isocapnic measure is used to determine the time course characteristics of hypoxic ventilatory decline and the poikilocapnic measure shows the ventilatory response to a hypoxic environment. A measurement regime incorporating these three procedures will permit a detailed assessment of the peripheral chemoreflex response to hypoxia that allows comparisons to be made between individuals and different physiological and environmental conditions.
Collapse
Affiliation(s)
- James Duffin
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada.
| |
Collapse
|
23
|
Severinghaus JW. Sightings. High Alt Med Biol 2007. [DOI: 10.1089/ham.2006.0813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
|