Two studies further our knowledge of altitude sickness

Last week there were reports of another breakthrough in the fight against altitude sickness. Researchers at The Roslin Institute at the University of Edinburgh made a surprising discovery. They found that the symptoms commonly suffered by those at altitude are in fact the result of two completely separate syndromes.

Previously scientists had failed to identify these syndromes as separate conditions. Because both just so happen to strike above 2500m. Falling oxygen levels, which are prevalent above this altitude, trigger both of these illnesses.

Researchers used as their study 292 people at altitudes between 3650m and 5200m in Bolivia and on Mount Kilimanjaro. Using advanced software, they grouped people according to their genetic make-up.

They then found that of all the symptoms of AMS (acute mountain sickness, aka altitude sickness), the only common one experienced by all parties was fatigue.

Sleep disturbance  was another common symptom. However, this was not necessarily accompanied by a headache.  Conversely, 40% of those suffering headaches did not report any sleep disturbance.

There is no one altitude sickness

The scientists concluded that the correlation between headaches and sleep disturbance are very poor. Poor enough, indeed, to indicate that the two are in fact manifestations of completely separate conditions.

So they are not all part of the same illness that, up to now, we have thought of as ‘altitude sickness’.

As Dr Ken Baillie, of the Roslin Institute, explained “For more than two decades we have thought of altitude sickness as a single disease. We have now shown that it is at least two separate syndromes that happen to occur in the same people at a similar time. Studying these syndromes in isolation will make it easier to understand the cause of each one, and to test new treatments.”

Using ultrasound to study the heart at altitude

This groundbreaking news follows another study that we first wrote about back in December. In this study, scientists claim to have discovered the underlying cause of altitude sickness. Researchers looked at how the heart reacts to the oxygen levels using ultrasound techniques.

Just 34 volunteers took part in this experiment. Researchers measured the volunteers at sea level initially. They then measured them again for a second time at high altitude. (In this case, the 3842m at the top of the cable car running up the Aiguille de Midi.)

From their observations, the team that led the research made a surprising discovery. It seems that those who had poor function in their heart’s right ventricle, and its ability to pump blood, went on to develop at least moderate symptoms .

The scientist who led the study, Dr Rosa Maria Bruno, explained the results as follows:

“If these results are confirmed by larger studies, it will be possible to identify vulnerable individuals and suggest particular behaviours and drugs.”

However, she also pointed out that the test is quite limited. In particular, only people who have spent at least 4 hours at high altitude can take the test. So there appears to be more work to be done here. But it seems like a good start. And a possible way to eventually solving the mysteries of AMS.