Wednesday, April 9, 2008

Bad News for High Altitude Mountaineering

There is an interesting article in this month's Scientific American Mind about a recent study linking high-altitude mountaineering with brain damage. Since several of my favorite people are currently in a mountaineering class at Eastern, I thought I'd share.

The researchers (Neurologist Nicol├ís Fayed and his colleagues in Zaragoza, Spain) used non-invasive brain scanning techniques to take a look at the brains of climbers, both professional and amateur, after completing Everest summit attempts or other high-altitude climbs around the world. The results don't look good: nearly every Everest climber had damaged tissue, and a large portion of those who climbed shorter peaks also showed damage. As the article explains, the damage is caused by hypoxia: "Lack of oxygen can directly damage brain cells. In addition, the walls of blood capillaries begin to leak at high altitudes, and the leaked fluid can cause dangerous swelling, pressing the brain outward against the rigid skull. Sometimes the optic nerves swell so badly they bulge into the back of the eye, degrading vision and causing retinal hemorrhages. Meanwhile blood, concentrated from dehydration and thickened by increased numbers of red blood cells, clots more easily. This clotting, along with the hemorrhage from the thinned capillaries, can cause a stroke. A climber with HACE [high-altitude cerebral edema] may experience amnesia, confusion, ­delusions, emotional disturbance, personality changes and loss of consciousness." What Fayed's study shows, however, is that even climbers who experienced none of these symptoms and seemed to have a high tolerance for hypoxia often show extensive damage. There is also a possible correlation between the speed of the climb and amount of damage. Some of the climbers of less extreme peaks, such as Aconcagua in the Argentine Andes, completed their summit much quicker than a typical Everest climber would. "All eight Aconcagua climbers in the study showed cortical atrophy on MRI scans. Seven showed enlarged VR spaces, and four showed numerous subcortical lesions. Some needed no scan to tell them their brains had been injured. One climber suffered aphasia (problems with speech), from which he recovered six months later. Two complained of transient memory loss after returning, and three others struggled with bradypsychia (slowed mental function)."

More bad news: The climbers involved in the study were reexamined three years after the initial scans were done, and the damage remained. Guess I'll hold off on that Everest summit I was planning.

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