Open AccessChanges in cerebral vascular reactivity and structure following prolonged exposure to high altitude in humans
Author(s) -
Foster Glen E.,
DaviesThompson Jodie,
Dominelli Paolo B.,
Heran Manraj K. S.,
Donnelly Joseph,
duManoir Gregory R.,
Ainslie Philip N.,
Rauscher Alexander,
Sheel A. William
Publication year - 2015
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.12647
Subject(s) - white matter , medicine , cardiology , effects of high altitude on humans , magnetic resonance imaging , anesthesia , nuclear medicine , radiology , anatomy
Although high‐altitude exposure can lead to neurocognitive impairment, even upon return to sea level, it remains unclear the extent to which brain volume and regional cerebral vascular reactivity ( CVR ) are altered following high‐altitude exposure. The purpose of this study was to simultaneously determine the effect of 3 weeks at 5050 m on: (1) structural brain alterations; and (2) regional CVR after returning to sea level for 1 week. Healthy human volunteers ( n = 6) underwent baseline and follow‐up structural and functional magnetic resonance imaging ( MRI ) at rest and during a CVR protocol (end‐tidal PCO 2 reduced by −10, −5 and increased by +5, +10, and +15 mmHg from baseline). CVR maps (% mmHg −1 ) were generated using BOLD MRI and brain volumes were estimated. Following return to sea level, whole‐brain volume and gray matter volume was reduced by 0.4 ± 0.3% ( P < 0.01) and 2.6 ± 1.0% ( P < 0.001), respectively; white matter was unchanged. Global gray matter CVR and white matter CVR were unchanged following return to sea level, but CVR was selectively increased ( P < 0.05) in the brainstem (+30 ± 12%), hippocampus (+12 ± 3%), and thalamus (+10 ± 3%). These changes were the result of improvement and/or reversal of negative CVR to positive CVR in these regions. Three weeks of high‐altitude exposure is reflected in loss of gray matter volume and improvements in negative CVR .