
The Mysterious Aging of Astronauts - avani
http://lemire.me/blog/2015/12/01/the-mysterious-aging-of-astronauts/
======
zeristor
I attended a talk [1] in which the made a case for the a British manned space
programme as another angle on investigating ageing [2]. Radiation, boneloss,
and a number of aspects. Ironically my memory of the talk is fading...

[1] [http://www.bis-space.com/2014/03/04/12501/uk-space-life-
and-...](http://www.bis-space.com/2014/03/04/12501/uk-space-life-and-
biomedical-sciences-a-launchpad-for-british-human-space-flight)

[2] [http://www.ukspacelabs.co.uk/about/5-strategy-r-d-
themes](http://www.ukspacelabs.co.uk/about/5-strategy-r-d-themes)

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taconacho
Is there a citation for the following claim? I've never heard of such a thing:

"But then more results started coming back. Not only do astronauts come back
with weak muscles and frail bones… But they also suffer from skin thinning,
atherosclerosis (stiffer arteries), resistance to insulin and they suffer from
loss of vision due to cataracts many years earlier than expected given their
chronological age. These symptoms look a lot like skin aging, cardiovascular
aging, age-related diabetes and so forth. In fact, it is pretty accurate to
say that astronauts age at an accelerated rate."

~~~
danesparza
In addition to the references in the article, Wikipedia (surprisingly) has a
nice article on the effects of spaceflight on the human body (with all sorts
of references):
[https://en.wikipedia.org/wiki/Effect_of_spaceflight_on_the_h...](https://en.wikipedia.org/wiki/Effect_of_spaceflight_on_the_human_body)

~~~
taconacho
Looks like my mistake was in thinking that the stated effects were occurring
_after_ astronauts had returned to Earth. At least that's what the title
sounds like. If these symptoms only apply to humans while they are in a
weightless environment then it sounds very much like sedentary disease (aka
sitting disease). Even rigorous exercise routines can't fully match the
effects of gravity on the human body.

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LordKano
Maybe it's attributed to the rigorousness of the selection process but I have
noticed the longevity of so many astronauts.

John Glenn, Neil Armstrong, Buzz Aldrin, Michael Collins and Edgar Mitchell
all lived beyond the average life expectancy of American males born when they
were born.

Our bodies have incredibly complex feedback loops and we evolved here, with a
constant 1G of gravity.

It's not surprising to me that exposure to Zero-G can have long lasting and
unexpected consequences.

~~~
Retric
Selection bias. Life expectancy at birth has little impact when astronauts are
all selected much latter in life.

At the extreme edge, the average age of people in nursing homes is much older
than life expectancy at birth. That does not mean nursing homes are good for
you.

~~~
LordKano
I certainly concede the possibility.

People who are healthiest in their mid to late 30s being more likely to live
into old age than those who are not is a plausible explanation for what I have
observed.

~~~
Retric
I think we are talking past each other. People who are alive at 30 can't die
at 5, but people at birth could die at 5. So, just by being 30+ or 60+ a
populations life expectancy increases. Which is why actuarial tables include
ages.

So, to see if Astronauts are living unusually longer than other people you
need to look at life expectancy's of people who where 30 around 1960's.

Now, they might sill be living longer than that group. But, it does not seem
like that's the comparison your making.

~~~
nilkn
[https://www.ssa.gov/oact/STATS/table4c6.html](https://www.ssa.gov/oact/STATS/table4c6.html)

This suggests a life expectancy of ~78 years old for someone 30 years old
today. Of course, as you stated, we'd really need statistics for someone who
was 30 years old in the 60s.

John Glenn, Neil Armstrong, Buzz Aldrin, Michael Collins and Edgar Mitchell
are all at least several years beyond 78, with Glenn at an impressive 94.

By the way, the life expectancy at birth in that table is 76, so evidently
reaching age 30 doesn't actually count for as much as I thought it would.

~~~
Retric
[https://xkcd.com/893/](https://xkcd.com/893/)

4 of the 12 people that walked on the moon have already died. If you look at
the people who have not died by age X, there life expectancy is going to be
based on that age.

PS: As to reaching age X, [http://www.businessinsider.com/social-security-
life-table-ch...](http://www.businessinsider.com/social-security-life-table-
charts-2014-3) A 30 year old male has a ~25% chance of reaching 90. But, these
sample sizes are tiny so that does not mean much.

~~~
lordnacho
> [https://xkcd.com/893/](https://xkcd.com/893/)

It's sad that they don't need a model of arrivals. I would like to at least
hope that someone will walk on the moon before 2035.

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mmastrac
Cache since it appears to be dead:
[http://webcache.googleusercontent.com/search?q=cache:SYsBpU-...](http://webcache.googleusercontent.com/search?q=cache:SYsBpU-28V4J:lemire.me/blog/2015/12/01/the-
mysterious-aging-of-astronauts/&hl=en&gl=us&strip=1&vwsrc=0)

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dennisnedry
Perhaps there needs to be more studies done on the effect of gravity and human
health? Conversely, are there other things in our air (pollutants) that are in
fact causing slower aging when on Earth?

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caio1982
Well, as to your first question, that's exactly the purpose of
[https://www.nasa.gov/content/one-year-crew](https://www.nasa.gov/content/one-
year-crew)

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stephengoodwin
On the reverse side, I've always wondered if being in a weightless environment
makes your muscles feel great[0], since they aren't working against gravity.
Over the years, gravity can create lots of problems for posture, which is why
swimming (which lessen the effects of gravity) feels great.

[0] I'm using "Feel" in a relative context, since muscle weakness/wasting will
not feel good once you're back in a non-weightless environment.

~~~
kbutler
My experience with swimming is that the drag from the resistant medium
outweighs the perceived "lift" from buoyancy.

I expect the disorientation, nausea, etc., would outweigh any short term
muscle-feel effects. For how weightlessness feels:
[http://science.howstuffworks.com/weightlessness2.htm](http://science.howstuffworks.com/weightlessness2.htm)

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S_A_P
Sounds to me that its related to the "exercise" related to living in 1G. I
wonder if the air mixture oxidizes the body more quickly as well.

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pcl
_They are also followed medically more closely than just about anyone on
Earth: they don’t indulge in regular fast food_

I wonder what they mean by that. Are astronauts explicitly banned from eating
fast food, and somehow monitored? Or are they just less likely to eat fast
food, since they pay close attention to their fitness and health?

~~~
derekp7
As far as I know, they haven't installed a McDonald's module on the ISS yet.

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eveningcoffee
I like the comment from _petero_ :

Perhaps the effect is due to lack of grounding.

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bizarref00l
It seems strange aging also affects other things.
[http://www.japantimes.co.jp/news/2014/04/11/national/sakura-...](http://www.japantimes.co.jp/news/2014/04/11/national/sakura-
from-space-blooms-early/)

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jimrandomh
Maybe there's a diet-related problem? Astronaut food has some pretty intense
constraints that Earth food doesn't, and has almost certainly been optimized
according to the false discoveries of the field of nutrition. They should have
a few people with different contrarian positions look over the food logs, and
see if there's anything really wrong there.

~~~
pc86
> _false discoveries of the field of nutrition_

I would love to hear about some of these.

~~~
Evgeny
My guess is that he meant things like "fat makes you fat and causes heart
disease", or "fruit juice is good for you", or "margarine is better for you
than butter" or "meat causes cancer" etc.

~~~
jimrandomh
Yes, these are all examples or tentative examples of the sort of thing I'm
talking about. (I don't know much about what they're eating up on the ISS,
though, so I don't know if they're applicable.)

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kayadx83
This is interesting. You feel gravity less when you are in fluids. Does this
mean all babies feel gravity differently because we all experience different
amounts of fluid in the womb (not to mention the variations in baby sizes)?
The impact is probably miniscule but I wonder if it has any effect on
development of babies in the womb.

~~~
hydrogen18
How exactly do you think buoyancy works? It's not like its anti-gravity
anymore than the chair I'm sitting in is.

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dogma1138
So the dawn of the 20th century radium spas are going to make a come back?
[https://en.wikipedia.org/wiki/History_of_radiation_therapy#J...](https://en.wikipedia.org/wiki/History_of_radiation_therapy#Joachimsthal_radium_spa_hotel)

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Joof
Microgravity is like alcohol; it effects so many systems in your body that
it's really difficult to pin down exactly what is causing problems where.

I imagine this question won't be seriously answered until we have an
artificial gravity system.

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thieving_magpie
I love this sentence, cracks me up:

"They are also followed medically more closely than just about anyone on
Earth: they don’t indulge in regular fast food."

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jostmey
One hypothesis: Solar and cosmic ionizing radiation ?

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username3
Certain bacteria in bodies die in space?

~~~
dogma1138
If they absorbed sufficient radiation to kill that much bacteria they would be
dead a week later. If you get a dose high enough to give you "radiation high"
you are a goner.

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tullianus
I'll repost the comment I made over there:

Have you guys heard about the entire field of study that is aerospace
medicine? I’m taking a course on it this semester (I’m a masters student in
aerospace engineering)–let me summarize some of the problems that your body
goes through during space travel.

Humans spend about 70% of their time either standing or sitting. That means
the human body is optimized for a hydrostatic pressure gradient like the one
illustrated here
([http://wiki.sdstate.edu/@api/deki/files/999/=1-BP_Change.png](http://wiki.sdstate.edu/@api/deki/files/999/=1-BP_Change.png)).
Blood pressure is much higher at your feet than at your head. In space,
however, there is no gravity to produce this gradient, so the cardiovascular
system equalizes its pressure. That’s why astronauts suffer from “puffy face”
(higher-than-usual fluid pressures in head) and “chicken legs” (lower-than-
usual fluid pressures in legs). In their first couple days in space,
astronauts lose about 1L of leg volume from each leg.

The CV system relies on internal pressure sensors to figure out how to
operate, and the new pressure distribution confuses it. Astronauts lose a lot
of blood plasma–it sort of ends up absorbed into the surrounding tissues. This
increases the relative concentration of red blood cells, which triggers the
body to slow down production of new ones. Also, the heart atrophies because it
doesn’t need to pump as hard to move liquid around the body.

When you come back from space, your body needs to rapidly readapt from
microgravity to one gee. It is not very good at doing that. That’s why 63% of
astronauts are unable to stand for ten minutes straight just after their
return from short-duration space missions (see video:
[https://www.youtube.com/watch?v=TPDST7EePXQ](https://www.youtube.com/watch?v=TPDST7EePXQ)).

There are other problems: the cells that are constantly building and
destroying your bones fall out of alignment when you’re in microgravity,
causing astronauts’ bones to change structure in a way that looks a lot like
accelerated aging. Why? Not clear, but possibly related to the lack of
repeated loading, as happens when you stand/walk in normal gravity. Astronauts
end up with huge concentrations of calcium in their blood, which causes kidney
stones. Astronauts in space average around 4 hours of sleep per night, and
very few of them eat enough calories to maintain their body weight, so they
lose muscle mass.

Aerospace medicine is about half medical studies of astronauts and half
studies of people on earth. It turns out that you can make most of these body
changes happen by having people lie on their backs with the bed tilted down
six degrees (head downward). Fascinating field. If you want to know more, I
recommend the textbook “Space Physiology” by Jay Buckey (amazon link here:
[http://smile.amazon.com/Space-Physiology-Jay-C-
Buckey/dp/019...](http://smile.amazon.com/Space-Physiology-Jay-C-
Buckey/dp/0195137256?tag=s4charity-20)).

