Might want to give up that fantasy of climbing Everest or K2. Very high altitude climbers appear to lose some brain mass as a result of their hobby.
A study of professional mountain climbers has shown that high-altitude exposure can cause subtle white and grey matter changes to the area of the brain involved in motor activity, according to the October issue of the European Journal of Neurology.
Italian researchers took MRI scans of nine world-class mountain climbers, who had been climbing for at least 10 years, before and after expeditions to Mount Everest (8,848 metres) and K2 (8,611 metres) without an oxygen supply. They compared their MRI brain scans with 19 age and sex matched healthy control subjects.
Both the climbers and controls were carefully checked to exclude the presence of any major systemic, psychiatric or neurological illnesses. None of the control group subjects had any history of high-altitude exposure over 3,000 metres.
The results demonstrated that the climbers showed a reduction in both the density and volume of white matter in the left pyramidal tract, near the primary and supplementary motor cortex, when their baseline measurements were compared with the control group.
And when the researchers compared the before and after scans for the climbers, they also found a reduction in the density and volume of grey matter in the left angular gyrus.
There can be costs to pushing your body beyond its limits. Oxygen starvation during high altitude ascents might inflict a cost as lost brain cells.
Climbers need a portable energy source that could concentrate oxygen from the atmosphere. People familiar with Robert Freitas's proposed artificial red blood cells called respirocytes might expect these nanodevices to some day make a walk up Everest fairly easy. But a 4 hour oxygen storage capacity for respirocytes won't take you through even one day of the hike up.
But one of the potential benefits of nanomedical devices is their ability to extend natural human capabilities. Suppose you wanted to permanently maximize the oxygen-carrying capacity of your blood by infusing the largest possible number of respirocytes. The maximum safe augmentation dosage is probably about 1 liter of 50% respirocyte suspension, which puts 954 trillion devices into your bloodstream. You could then hold your breath for 3.8 hours, at the normal resting metabolic rate. At the maximum human metabolic rate, something like a continuous Olympic-class 50-meter dash exertion level, you could go for a full 12 minutes without taking a breath. Afterwards, your entire capacity is recharged by hyperventilating for just 8 minutes - then you're ready to go again.
Maybe a nanomaterial clothing could integrate with the respirocyte system so that most of your external surface area could be harnessed for oxygen collection. Nanotech will enable more extreme sports. Picture a group of people walking across the Hudson River on the bottom of the river. Or how about a group of people walking under the length of the Golden Gate Bridge on the bottom of the inlet to the bay? Combine respirocytes with an active system for pulling oxygen out of water and humans could do a lot of underwater hiking. Long life batteries would be needed for seeing though.
|Share |||Randall Parker, 2008 October 16 09:45 PM Aging Studies|