Text by West Coast Editor Steve Casimiro
High-altitude climbing can cause brain damage that impairs motor skills and memory, reports a study by Italian researchers published this month in the European Journal of Neurology.
Exposure to the oxygen-depleted heights of high altitudes reduced the
volume and density of “white matter” near what’s called the motor
cortex and in “grey matter” near the left angular gyrus. Nine climbers
with at least 10 years experience each were tested with MRI scans
before and after trips to Mt. Everest or K2 that did not use
supplemental oxygen. They were measured against a group of 19 control
subjects and the results were examined by testers who didn’t know which
was which. One of the climbers summited both Everest and K2, two others
summited one or the other, and the rest spent at least two weeks about
“Our results provide evidence that extremely high-altitude climbs with
no external oxygen supply may cause subtle changes in brain tissue,
even when well acclimatised individuals do not experience any
neurological symptoms,” said Dr Margherita Di Paola of the Rome-based
Neuroimaging Laboratory at the IRCCS Fondazione Santa Lucia.
There was no measured impairment in neurological tests before and after
the expeditions, but two-thirds of the climbers scored lower than
average on what’s called the Digit Symbol test, which measures the
ability to anticipate and adapt. Four of the nine also score lower than
average on visual/motor skills, three scored lower in short-term
memory, and three scored lower in long-term memory.
“Some of the subjects did show abnormal scores on the
neuropsychological tests, but in these cases there was no significant
difference between the baseline and follow up results,” said Di Paola.
“This suggests that there were no significant changes as a result of a
“As they had been carefully checked for any pathological conditions
that could cause these abnormal scores, we conclude that these test
results are most likely to be due to progressive, subtle, brain insults
caused by repeated high-altitude exposure.”
- Nat Geo Expeditions