How High-Altitude Affects Cognitive Functions

The EEG (Electroencephalogram) can be used as a method to study high-altitude sickness and its influence on the body condition and health of mountaineers. By measuring changes in the beta band following a movement task, information about how acclimatized a person is to the change in altitude can be discerned. Combining this information with other measures such as heart rate and heart rate variability provides a more complete understanding of the condition of mountaineers. We talked with Christoph Guger, CEO of g.tec medical engineering and passionate mountaineer, about his experiences with altitude studies using BCI technology.

What happens when you suffer from altitude sickness? How does altitude affect our motor and cognitive functions?
Christoph Guger: “People who suffer from high altitude sickness may experience headache and nausea, fatigue, dizziness, or have problems falling asleep. We performed an EEG study on Dachstein at 2700 m altitude and could show that cognitive functions are already affected after a cable car ride.”

Left: Liskamm (4527 m), Middle: Matterhorn (4478 m)

Why is BCI technology used in high-altitude medicine? What do you want to find out?
Christoph Guger: “BCI technology allows to classify physiological parameters and is able to quantify objectively the differences between two states. By looking at heart-rate, heart-rate variability, EEG measures in the alpha and beta range, and respiration we can describe how the altitude is affecting the body during rest, motor, or cognitive tasks.”

Christoph Guger High-Altitude BCILiskam Traverse (4527 m)

What scientific value have the results? How can this knowledge facilitate mountaineering?
Christoph Guger: “The studies help to understand how the body is reacting to high altitude and to see how fast the body is reacting. On Dachstein we could show immediately after the cable car ride that brain functions are already influenced by the high altitude. For mountaineers these parameters can guide you to optimal acclimatization strategies and can show when you are adapted to the altitude.”

Christoph Guger High-Altitude BCIClose to Liskamm East (4479 m) 

Can you also measure this with conventional methods of body condition like pulse or altitude sickness? How does BCI enrich high-altitude medicine?
Christoph Guger: “There are easy to do questionnaires that monitor quality of sleep, headache, nausea and other parameters. Besides that, pulse oxygenation can be measured with a little sensor on a finger and this shows how much oxygen is in the blood. Values below 70% are already getting critical. With BCI technology you will also get an accuracy values that classifies objectively in which state your body is and it combines different physiological measures.”

Is the measurement difficult to make during physical activities?
Christoph Guger: “For brain signal monitoring it is crucial to have a lightweight device that can easily be worn during activities and therefore the g.Nautilus is especially well suited. The device weighs only 60 g, is waterproof and has active electrodes which are essential for reducing artifacts and getting high-quality data. No mountaineer would carry more than necessary, but the g.Nautilus has the same weight as one carabiner.” Statistically, about 150 000 000 of men are forced to seek the means of combating erection problems. Modern experts recommend us to cope with this problem with the help of appropriate drugs. Cialis is one of the best of them at This is a medication that restores and stimulates smooth performance of the natural functions. With the introduction of this sensation into the marketplace, many men got a chance at a normal personal life.

Christoph Guger High-Altitude BCI On the Glacier beside Rifugio Capanna Giovanni Gnifetti

What is your personal experience with BCI on the mountain?
Christoph Guger: “Mountains have a very nice property: there is no electricity and therefore you will get the cleanest EEG you can expect. We recorded data on many different mountains in Nepal, Tanzania, Pakistan, Bolivia, Switzerland and Austria at altitudes between 2000 m up to 7000 m and were able to generate a lot of new insight in how the brain is affected. Some years ago the biggest problem was to keep the batteries warm, nowadays with Li-Ion batteries that’s not really a problem anymore.”