Persistent cognitive impairment in climbers after repeated exposure to extreme altitude.

We performed neuropsychological testing in eight world class climbers who had reached summits higher than 8,500 meters without supplementary oxygen. Five had mildly impaired concentration, short-term memory, and ability to shift concepts and control errors. There were no defects in perception or other cognitive activities. The pattern of impairment suggests malfunctioning of bifronto-temporo-limbic structures. Repeated extreme-altitude exposure can cause mild but persistent cognitive impairment.