High-altitude mountain climbers who ascend without an oxygen supply may return to the ground with less tissue in brain areas related to movement, a study suggests.
Italian researchers found that when they took brain scans of nine world-class climbers before and after expeditions up Everest and K2, the climbers showed signs of subtle brain atrophy after their descents.
The tissue changes were mainly seen in brain areas related to motor control. In addition, the climbers showed subtle brain-volume differences when their scans were compared with those of 19 non-climbers; the differences were again localised to areas involved in movement.
The significance of the brain changes is not clear. Tests of the climbers' neurological and psychological function - including memory and movement skills - revealed no significant changes after the climb, according to Dr Margherita Di Paola, a researcher at the University of L'Aquila and the Santa Lucia Foundation in Rome.
Several climbers did, however, have some lower-than-average test scores both before and after their expedition, the researchers report in the European Journal of Neurology.
In particular, six climbers scored below the norm on a test of "executive functions" such as the ability to adapt to changing situations.
The climbers, all men, were relatively young and in good health, Di Paola and her colleagues point out.
Unsure if oxygen will prevent atrophy
"Thus," they write, "the abnormal scores on the neuropsychological tests can be explained as the result of progressive, subtle, brain insults likely due to repeated high-altitude exposures."
As is the norm with world-class climbers, Di Paola told Reuters Health, the men in her study ascended without supplemental oxygen. It's not clear, she said, whether using oxygen would prevent the brain atrophy she and her colleagues found.
"In theory," Di Paola said, "this is not impossible to study, but practically it is."
That's because few elite climbers are willing to use an oxygen supply, she noted, as many consider it akin to using a life ring in the swimming pool. – (Amy Norton/Reuters Health)
SOURCE: European Journal of Neurology, October 2008.
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