The cerebral effects of ascent to high altitudes

Ml, Wilson; Newman, Stanton; Imray, Chris

doi:10.1016/s1474-4422(09)70014-6

Cited by 420 publications

(357 citation statements)

References 153 publications

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“…2007; Wilson et al. 2009). These changed hemodynamic events should alter the T2/T2* value of the brain tissue, and altered the T2/T2* that causes SNR change in fMRI and dMRI (Uematsu et al.…”

Section: Discussionmentioning

confidence: 99%

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Long‐term acclimatization to high‐altitude hypoxia modifies interhemispheric functional and structural connectivity in the adult brain

Chen

Li²,

Han³

et al. 2016

Brain and Behavior

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BackgroundStructural and functional networks can be reorganized to adjust to environmental pressures and physiologic changes in the adult brain, but such processes remain unclear in prolonged adaptation to high‐altitude (HA) hypoxia. This study aimed to characterize the interhemispheric functionally and structurally coupled modifications in the brains of adult HA immigrants.MethodsWe performed resting‐state functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) in 16 adults who had immigrated to the Qinghai‐Tibet Plateau (2300–4400 m) for 2 years and in 16 age‐matched sea‐level (SL) controls. A recently validated approach of voxel‐mirrored homotopic connectivity (VMHC) was employed to examine the interhemispheric resting‐state functional connectivity. Areas showing changed VMHC in HA immigrants were selected as regions of interest for follow‐up DTI tractography analysis. The fiber parameters of fractional anisotropy and fiber length were obtained. Cognitive and physiological assessments were made and correlated with the resulting image metrics.ResultsCompared with SL controls, VMHC in the bilateral visual cortex was significantly increased in HA immigrants. The mean VMHC value extracted within the visual cortex was positively correlated with hemoglobin concentration. Moreover, the path length of the commissural fibers connecting homotopic visual areas was increased in HA immigrants, covarying positively with VMHC.ConclusionsThese observations are the first to demonstrate interhemispheric functional and structural connectivity resilience in the adult brain after prolonged HA acclimatization independent of inherited and developmental effects, and the coupled modifications in the bilateral visual cortex indicate important neural compensatory mechanisms underlying visual dysfunction in physiologically well‐acclimatized HA immigrants. The study of human central adaptation to extreme environments promotes the understanding of our brain's capacity for survival.

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Section: Discussionmentioning

confidence: 99%

“…2004; Wilson et al. 2009) are important. The most prominent and important impact of living in an HA environment is chronic hypoxia.…”

Section: Introductionmentioning

confidence: 99%

Long‐term acclimatization to high‐altitude hypoxia modifies interhemispheric functional and structural connectivity in the adult brain

Chen

Li²,

Han³

et al. 2016

Brain and Behavior

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“…These are all nonspecific, and insomnia, in particular, is very prevalent in healthy individuals at high altitude. Progression of symptoms including nausea and headache not responding to first-line antiemetics and analgesics and increasing lassitude may point to progression of AMS to HACE [5]. The leading signs of HACE are truncal ataxia and clouded consciousness.…”

Section: Ams and Hacementioning

confidence: 99%

Acute high-altitude sickness

2017

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At any point 1-5 days following ascent to altitudes ⩾2500 m, individuals are at risk of developing one of three forms of acute altitude illness: acute mountain sickness, a syndrome of nonspecific symptoms including headache, lassitude, dizziness and nausea; high-altitude cerebral oedema, a potentially fatal illness characterised by ataxia, decreased consciousness and characteristic changes on magnetic resonance imaging; and high-altitude pulmonary oedema, a noncardiogenic form of pulmonary oedema resulting from excessive hypoxic pulmonary vasoconstriction which can be fatal if not recognised and treated promptly. This review provides detailed information about each of these important clinical entities. After reviewing the clinical features, epidemiology and current understanding of the pathophysiology of each disorder, we describe the current pharmacological and nonpharmacological approaches to the prevention and treatment of these diseases.

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“…A large body of data demonstrated that people travelling to high altitudes were subjected to cognitive decline such as short‐term memory, working memory, verbal fluency, and language production (Pelamatti, Pascotto, & Semenza, 2003; Wilson et al., 2009). Moreover, a recent report suggested that the native people living in different high altitudes (3,700, 4,500, and 5,100 m) for long time showed cognitive impairment symptoms compared to human population at sea level (Zhang et al., 2013).…”

Section: Discussionmentioning

confidence: 99%

“…A wide range of past studies have demonstrated that hypoxia at high altitude induces neurophysiological conditions such as dizziness, insomnia, headaches, nausea, vomiting, and fatigue, and even possibly high altitude pulmonary edema, and cerebral edema that is potentially fatal (Basnyat & Murdoch, 2003). Furthermore, it could also trigger neurocognitive dysfunction including learning, memory, language, vision, and mood (Hu, Xiong, Dai, Zhao, & Feng, 2016; Wilson, Newman, & Imray, 2009). In addition, cognitive deficits may last for some time following people's coming back to sea level from plateau (Bonnon, Noel‐Jorand, & Therme, 2000).…”

Section: Introductionmentioning

confidence: 99%

Oxiracetam or fastigial nucleus stimulation reduces cognitive injury at high altitude

Shi

Xiong

et al. 2017

Brain and Behavior

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BackgroundCognitive impairment is common in people travelling to high altitude. Oxiracetam and electrical stimulation of cerebellar fastigial nucleus may have beneficial impacts. This study was to investigate the effects of preconditioning with Oxiracetam or fastigial nucleus stimulation (FNS) on cognitive decline following the ascension to high altitude.MethodsThe study was conducted on 60 male military voluntary members who were divided into control group, Oxiracetam group, and fastigial nucleus stimulation group. Transcranial doppler sonography, auditory evoked potential, electroencephalogram (EEG), and cognitive assessments were performed.ResultsPeople could still suffer cognitive dysfunction at 4,000 m high altitude despite that they have lived at 1,800 m altitude for several years. The 4,000 m altitude environment also prolonged P300 and N200 latencies. Both Oxiracetam and FNS improved cognitive function, reduced the prolonged latencies of Event Related Potentials (P300 and N200), decreased the average velocity of brain arteries, and enhanced EEG power spectral entropy at 4,000 m altitude.ConclusionsNeurophysiological evidences suggest the underlying mechanism of cognitive impairments. Both Oxiracetam and FNS can reduce cognitive decline post arrival at high altitude. They could be a potential pretreatment method for cognitive dysfunction resulted from high altitude.

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The cerebral effects of ascent to high altitudes

Cited by 420 publications

References 153 publications

Long‐term acclimatization to high‐altitude hypoxia modifies interhemispheric functional and structural connectivity in the adult brain

Long‐term acclimatization to high‐altitude hypoxia modifies interhemispheric functional and structural connectivity in the adult brain

Acute high-altitude sickness

Oxiracetam or fastigial nucleus stimulation reduces cognitive injury at high altitude

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