
Why is cognitive function impaired at high altitude? - prostoalex
https://www.outsideonline.com/2378771/why-mountains-make-you-dumber
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glastra
It seems to me that metabolic state should also be taken into account.

A lower respiratory quotient for fat metabolism means expelled CO2 is much
lower when utilising fat for energy (CO2 litres per kcal [0]), making
respiration easier and requiring less tidal volume. A lower CO2 concentration
in the alveolar space means O2 can be more effectively taken into the blood
[1].

Hormonal disruptions also seem to play a role [2].

[0]: [http://hyperphysics.phy-
astr.gsu.edu/hbase/Biology/metab.htm...](http://hyperphysics.phy-
astr.gsu.edu/hbase/Biology/metab.html)

[1]:
[https://academic.oup.com/bjaed/article/13/1/17/281180](https://academic.oup.com/bjaed/article/13/1/17/281180)

[2]:
[https://www.ncbi.nlm.nih.gov/pubmed/30008674](https://www.ncbi.nlm.nih.gov/pubmed/30008674)

~~~
HyruleanHero
Would it be fair to say that a conclusion you could draw from the data you
outlined here would be that people currently in ketosis would fair better at
higher altitudes?

Sorry if I'm misunderstanding this, this is very far from my area of
expertise.

~~~
glastra
I derive that same conclusion by using common sense, but unfortunately I don't
have any answer other than that. I could find some anecdotes online, but
that's all.

There's also this:
[https://www.ncbi.nlm.nih.gov/pubmed/24917038](https://www.ncbi.nlm.nih.gov/pubmed/24917038)

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navbaker
I had to do a session in an altitude chamber as part of training in my early
military career. I remember how scary it was feeling like I had just sat down
on the bench and been there for no more than 3-4 minutes tops when I was told
time was up, but then watching the film of my session and realizing I had been
in for 30 minutes and couldn’t perform the simplest tasks the trainers were
instructing me to do.

~~~
mikejb
Destin from the 'Smarter Every day' YouTube channel did something similar (in
a PSA-sort of style), and it's partly funny, partly scary to watch:
[https://youtu.be/kUfF2MTnqAw](https://youtu.be/kUfF2MTnqAw)

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trhway
>First, thin air alone doesn’t fully explain the cognitive deficits observed
in mountain climbers, since the Kilimanjaro group fared worse than the
altitude chamber group.

they should have made the chamber group doing heavy weight-lifting and
treadmill running in the chamber (with thermostat set to -40 degrees) and i
bet the results would be very close.

>And second, fatigue from prolonged exercise doesn’t explain the difference,
since the ski touring group didn’t show any negative effects.

if anything, cross-country skiing pumps you up with energy and overall great
feeling. Your brain works even better after that, and even of you get very
tired, it isn't really a fatigue like you get during even modest mountain
hiking (did Shasta once and it was pretty tough for me even just a bit beyond
4km - you feel really slow and remembering some stuff later with friends -
happen to be more stupid than usual too). They should have tested super-
marathon of 100mi instead of cross-country skiing.

The article somehow dances around obvious - oxygen insufficiency (like at high
altitude) which naturally gets aggravated by heavy physical activity/exercise
as well as cold which at the altitude slows down body energy production while
taking its significant share of produced energy (at high altitudes there is
also some effect that digesting food isn't energy efficient anymore or
something like this).

Any one factor alone that they tested - like the chamber - may just not be
enough to hit the threshold where oxygen insufficiency (more precisely -
resulting balance of energy production and consumption in the body) starts to
affect the brain. Especially given that our body prioritizes oxygen delivery
to the brain (just look at the blood vessels diagram).

~~~
tim333
I climbed Kili with an upmarket, catering to old rich folk, tour operator and
they made a big deal about going very slowly and not getting out or breath.
They said that way about 99% of people including unfit tourists can make the
top whereas if you go fast a lot get sick. It was a bit frustrating going at a
pace where you could have used a zimmer frame but it seemed to work.

------
glandium
Relatedly, Destin from Smarter Every Day did a video about what happens with
oxygen deprivation.
[https://www.youtube.com/watch?v=kUfF2MTnqAw](https://www.youtube.com/watch?v=kUfF2MTnqAw)

~~~
mettamage
That was scary to watch. I've had a similar experience [3] performing the Wim
Hof Method [1] under medical supervision [2]. For 10 to 20 seconds they were
asking me the question of: "Mettamage, what is your name?!" And it took me 10
to 20 seconds to _register_ the question.

Moreover, I wasn't the only one and also not the extreme one. My friend (whom
I supervised myself) was out for 30 seconds and there was one person during
the experiment who seemed to be out for 2 to 3 minutes. The doctors were
rushing to get an oxygen mask but then he 'woke up' again and was normal.

I think in the case of the Wim Hof Method training phase what ultimately
happens is that you instinctively breath again at some point and therefore get
normal oxygen again (after not having it for 2 to 3 minutes _after_ breathing
all your oxygen out).

[1] There's a training phase in the Wim Hof Method where you can have a severe
lack of oxygen. When you use the actual Wim Hof Method in order to battle the
cold you won't experience it. The training phase is designed for you to
understand more intuitively how to do it.

[2] I was a test subject for this scientific experiment:
[http://www.innerfire.nl/files/pnas.pdf](http://www.innerfire.nl/files/pnas.pdf)
\-- non-paywalled PNAS publication -- PNAS link:
[https://www.pnas.org/content/111/20/7379](https://www.pnas.org/content/111/20/7379)

[3] See the scientific explanation behind it here:
[https://news.ycombinator.com/item?id=18911674#18919660](https://news.ycombinator.com/item?id=18911674#18919660)
\-- while oxygen levels stay at 99%, the availability is a lot less. It does
mention that the blackout itself is caused by hypoxia.

~~~
superpermutat0r
It's a bit off-topic but what is the conclusion then, is Wim Hof method safe
to do long-term and in a safe environment without medical supervision?

------
garyrob
I participated in a trek in Nepal, the high point of which was ascending to
the peak of Kala Patthar (chosen because of the great views of Everest it
offers; we got great photos of an avalanche in progress there). It's 5,644.5 m
(18,519 ft). We absolutely felt the lack of oxygen. It was a strange feeling,
like nothing else I've experienced. I definitely wouldn't have had the
competence to do much else than mindlessly climb up and mindlessly climb down
again on the day we did the peak (other than snapping some photos)!

My wife is a retinal surgeon. She was interested in the effects high altitude
on the retina, since the retina can, in some ways, almost be almost considered
to be part of the brain. At a lower elevation than the top of Kala Patthar,
she took out a magnification instrument and could spot some mild hemorrhaging
on my retina. Not enough to worry about but enough that she could see it. It
was interesting and a bit scary to think what could be going on in our brains.

I can't imagine how people climb Everest without oxygen. But one factor is
that most of them probably take more time to acclimatize than we did. (It took
us 2 weeks to trek to the peak.)

[https://en.wikipedia.org/wiki/Kala_Patthar](https://en.wikipedia.org/wiki/Kala_Patthar)

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taneq
It'd make sense that even if the human brain can cope on the oxygen available
at higher altitudes (since versatility is kind of our thing), it might not do
so well at high altitudes while _also_ exercising vigorously, since then the
brain and the muscles are competing for scarce oxygen.

~~~
leejo
Kind of anecdata here - I live at 1300m all year round, and get a reasonable
amount of exercise throughout the year (20min walk every day, cycling in the
summer, snowboarding in the winter most weekends). So I guess I fit somewhere
between the "Altitude plus prolonged exercise" and "No altitude plus no
exercise" group ("Some altitude plus some exercise"?)

Anyway, at the start of the ski season every year I go to the glacier and
snowboard there, as they always open a couple of months before my home resort.
The glacier is around 3000m and requires a reasonable amount of effort to get
around. Usually the first couple of trips there result in me not feeling that
well, occasionally I might really feel bad enough to call it a day. I
definitely can feel the affect on my body/mind.

In a way I guess that agrees with the last paragraph of the article.

~~~
StreakyCobra
This sounds like "Diablerets"/"Glacier 3000" no? :)

~~~
leejo
Correct!

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lenticular
I've climbed in the Andes in the past, getting as high as 6700m. I would
really guess that poor sleep is the major factor aside from oxygen
deprivation. It's very difficult to sleep at those altitudes, both from lack
of oxygen and the difficult physical conditions.

The human body's breathing is controlled by CO2 in the blood. If you aren't
getting a lot of oxygen, you aren't making enough CO2, so you are not
breathing enough. This is the main cause behind altitude sickness. It takes
time for your body to adjust its breathing rate.

This issue is worse at night. This is the reason behind an adage "climb high,
sleep low." Many people even get Cheyne-Stokes breathing, which causes one to
wake up hyperventilating kind of like sleep apnea.

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ipnon
I just got back from the Rockies. I noticed my usual anxiety at sea level was
completely gone.

~~~
agent008t
Same. I wonder why? I could feel it coming back as I was descending back to
sea level.

~~~
tim333
I've heard it said the effects of altitude on the brain are rather similar to
those of alcohol. Maybe it's like having a couple of beers / sobering up?

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bradknowles
Because you don’t have enough oxygen getting to your brain cells?

~~~
greenbush
Maybe read the article first before criticizing it? :) The article
specifically addresses that and explains how this is more complicated than
just oxygen deprivation.

"It’s not obvious why, though. The obvious culprit for reduced cognitive
function is the thin high-altitude air depriving your brain of oxygen."

~~~
speakeron
But what the article doesn't address is that the same effect is seen in flying
at high altitudes without supplementary oxygen, even in the absence of _sleep
deprivation, dehydration, and simple physical exhaustion_.

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fallingfrog
“The most unambiguous—and unsurprising—finding is that the Kilimanjaro group
had seriously impaired attentional capacity at the summit..”

You’re going to tell me that people might act distracted when trying to do
some memory test while standing looking at the spectacular view in the blowing
freezing wind on top of a mountain they just climbed? No way.

Next amazing result: people make 30% more errors on their tax returns while
skydiving..

~~~
fallingfrog
Hah, sorry, I guess that was a bit snarky. Still, this is a very silly study.

