High Altitude Brain Damage

The dangers of high altitude have been covered before on this site, but permanent brain damage was not one of the risks looked at. Unfortunately, recent evidence shows that this is a real possibility, and at lower elevations than many would have guessed. Although backpacking is not necessarily a high-altitude activity, it can be, so consider this a warning.

Outside Magazine reported in their October 2009 issue on the research done by Doctor Nicholas Fayed, a neuroradiologist in Spain. He has been looking at MRI scans of the brains of climbers, both before and after high altitude climbs. What he has found is evidence of permanent brain damage occurring from single trips, and much more commonly than scientists previously suspected.

There are three basic types of brain damage from exposure to high altitude.

Cortical Atrophy - This is from the loss of neurons in the cerebral cortex, the part of the brain that handles conscious thought and perception. It has now been shown that single trips to high enough elevations can cause a permanent damaging and shrinkage of the cortex.

Enlarged Virchow-Robin Spaces - This widening of VR spaces, the spaces around blood vessels in the brain, is normally seen in age-related conditions like dementia, Alzheimer's and general cognitive decline. It is now evident that high altitude can also cause this.

Subcortical Lesions - These affect the white matter underneath the cerebral cortex. Climbers suffer from this due to small strokes resulting from clots in their thickened blood. The damage can be widespread and permanent.

Dr. Fayed relates how one man forgot his phone number after coming down from Aconcagua (22,800 feet), and had trouble remembering what he went to a store for by the time he arrived there. A brain scan confirmed the damage. This is permanent damage in most cases.

Perhaps most disturbing to those who merely hike or backpack in the mountains is the story of seven trekkers who went to the top of Mont Blanc in France in 1998. The summit is only 15,771 feet above sea level, and none of them reported any signs of altitude sickness. But when their brains were scanned a few days later, three were found to have damage. Two had enlarged Virchow-Robin spaces, and one of those also had cortical lesions. One had cortical atrophy - a permanent loss of gray matter that can make thinking more difficult.

Before and after scans of the brains of those who climbed to high altitude on other mountains has shown similar damage. One study of 21 seasoned climbers showed that 60% of them showed signs of cortical atrophy. Worse news: It is suspected that amateurs are at greater risk due to improper acclimatization.

High Altitude - Good and Bad News

A study of seven Sherpas who climbed high but also lived relatively high showed only one had signs of brain damage. This indicates the importance of proper acclimatization.

Medical authorities who specialize in high altitude medicine recommend a a day or so at 5,000 feet if you are coming from sea level, and then ascending at just 2,000 feet per day once above 9,000 feet. The more conservative advice (which is becoming more common) is to keep it to 1,000 feet per day above 9,000 feet. That could be difficult for those who want to hike up the fourteeners in Colorado, although if they live there they likely have some acclimatization already (most of the state is above 4,000 feet).

There is more to this though. In the research done so far it seems clear that...

High Altitude Brain Damage continues here... Altitude.

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