Zero Gravity Orbital Habitation Causes Changes that are at Least Superficially Similar to Accelerated Aging

That old people will go into orbit to escape the rigors of gravity and thus live longer in their declining years was a staple of golden age and later science fiction. These works were written at a time in which our knowledge of human biochemistry - and the application of that knowledge to medicine - was crude in comparison to today. It is fascinating that we can say that for such a short span of years, a mere short lifetime past, but the differences between the medicine of the 1950s and the medicine of today are profound indeed. The writers of that time largely envisaged a future incorporating great gains in energy generation, and a consequent diaspora from Earth, while computation, medicine and the human condition remained much unchanged; older spacemen in the outer reaches struggling with heart disease in their fifties. Instead we found that expanding the generation, storage, transmission, and application of energy is very hard, and the largely unanticipated information revolution occurred instead. We lost the near future of cheap heavy lift to orbit and the solar system at our beck and call, but gained Moore's Law, biotechnology, nanotechnology, a pervasive internet, and medical progress that is in the early stages of conquering heart disease and may yet save us from all of degenerative aging.

As it turns out, retreating from the rigors of gravity may well have the opposite effect to that imagined by the authors of the last century. Among the alterations produced by orbital habitation in zero gravity are those that appear, at least superficially, much like accelerated aging of the cardiovascular system. The root causes have yet to be pinned down, since very few people are actually researching this topic, but since the onset of these symptoms is fairly rapid, I'd guess at the cause being more a matter of regulatory dysfunction than increased tissue damage, such as the presence of cross-links related to arterial stiffening in aging. Here I'll point out a few links to the work of one research group on this topic in recent years:

Waterloo to lead new experiment aboard International Space Station

The experiment will link changes in astronauts' hearts and blood vessels with specific molecules in the blood to determine why astronauts experience conditions that mimic aging-related problems and chronic diseases on earth. The findings will help identify important indicators for chronic disease and assist with the development of early interventions for people on earth. "We know that astronauts return from space with stiffer arteries and resistance to insulin, conditions affecting many adults as they age. For the first time, we will be able to track exactly how - and why - the body's blood vessels change, and use these findings to potentially improve quality of life and the burden of chronic disease."

"In space, astronauts' bodies show aging-like changes much faster than on Earth. The International Space Station provides a unique platform to study aging-related conditions providing insights that can be used to help understand some of the biggest health issues affecting society. Our research to date suggests that even though astronauts exercise every day, the actual physical demands of tasks of daily living are greatly reduced due to the lack of gravity. This lifestyle seems to cause changes in the vascular system and in the body's ability to regulate blood glucose that would normally take years to develop on earth."

U.Waterloo - Vascular Aging and Space Research Program

We study factors related to cardiovascular health with aging. One focus is on blood pressure regulation and its impact on brain blood flow to help us understand some of the factors that could contribute to falls in the elderly, especially those that occur on rising from bed. Another focus is on aging blood vessels. We have reported a strong link between peripheral arterial stiffness and a reduction in brain blood flow. Our space research program is very active. We recently completed the study Cardiovascular and Cerebrovascular Control on Return from the International Space Station (CCISS). We are currently collecting data for the project Cardiovascular Health Consequences of Long-Duration Space Flight (Vascular).

Cardiovascular Health Consequences of Long-Duration Space Flight (Vascular)

Cardiovascular Health Consequences of Long-Duration Space Flight (Vascular) investigates the impact of long-duration space flight on the blood vessels of astronauts. Space flight accelerates the aging process, and it is important to understand this process to develop specific countermeasures. Data is collected before, during, and after space flight to assess inflammation of the artery walls, changes in blood vessel properties, and cardiovascular fitness.

Spaceflight can cause stiffening of the arteries, affecting the body's ability to control blood pressure. This investigation assessed the blood vessels of astronauts and found decreased flexibility of the carotid artery during flight. Researchers found no relationship between the level of physical fitness and this decrease. The experiment also provided data on the mechanisms behind increased arterial stiffness from spaceflight. Further research is needed to establish effective ways to counter the cardiovascular consequences of spaceflight and ultimately help treat increased arterial stiffness from aging on Earth, which can cause high blood pressure and organ damage.

Impaired cerebrovascular autoregulation and reduced CO2 reactivity after long duration spaceflight

Long duration habitation on the International Space Station (ISS) is associated with chronic elevations in arterial blood pressure in the brain compared with normal upright posture on Earth and elevated inspired carbon dioxide. Although results from short-duration spaceflights suggested possibly improved cerebrovascular autoregulation, animal models provided evidence of structural and functional changes in cerebral vessels that might negatively impact autoregulation with longer periods in microgravity. Seven astronauts (1 woman) spent 147 ± 49 days on ISS. Preflight testing (30-60 days before launch) was compared with postflight testing on landing day or the morning 1 or 2 days after return to Earth. The results indicate that long duration missions on the ISS impaired dynamic cerebrovascular autoregulation and reduced cerebrovascular carbon dioxide reactivity.

Recent findings in cardiovascular physiology with space travel

The cardiovascular system undergoes major changes in stress with space flight primarily related to the elimination of the head-to-foot gravitational force. A major observation has been that the central venous pressure is not elevated early in space flight yet stroke volume is increased at least early in flight. Recent observations demonstrate that heart rate remains lower during the normal daily activities of space flight compared to Earth-based conditions. Structural and functional adaptations occur in the vascular system that could result in impaired response with demands of physical exertion and return to Earth. Cardiac muscle mass is reduced after flight and contractile function may be altered. Regular and specific countermeasures are essential to maintain cardiovascular health during long-duration space flight.
Comments

IMO, this is a total waste of time and money. It's very easy to make artificial gravity (simply rotate your ship with a tether), but nevertheless people are researching the effects of zero gravity in the human body since the 1960's. It's research for the sake of research (or for the sake of make a living with this research).

Posted by: Antonio at December 5th, 2015 4:22 AM

@Antonio

Hi Antonio, I understand what you mean. It seems all in vain when our efforts should be redirected towards rejuvenation therapies, on Earth, since it is where we live and most likely will live in 200 years time too. Perhaps, there will be certain colony formed on other planets and we may need to leave Earth and find other habitable places (moon, mars...à la The Martian, Interstellar, Elysium, Event Horizon, First Contact, Alien, Appolo, Avatar, X-Files, Men in Black, 2000 a Space Odyssey, Star Wars, Star Trek movies, n...), or perhaps aliens (those hidden martians coming over) will show up (à la Independence Day or District 9),or robots will automate things and replace us (A.I., Ex-machina, Her, Ghost in The Shell, Chappie, Robocop, Terminator, I, Robot) on second thought,
most likely not.

In those cases, researching about leaving and surviving out there (on other planets or worlds) could be a good thing when on Earth, things don't go so well (the famous overpopulation, resource shortage, people screaming at each other to tear their throats/anarchy/poverty/war/famine, etc). Knowing how to survive in space will be extremely important down the line at some point (perhaps in 400 or 500 years (conservative real estimate, it takes half a millenium for Extreme life changing things to happen, though perhaps because of ultra-progress we could cut in half), but most likely not even in the next one or two centuries), studying how body's' reaction to different gravity and fields is an important first step towards knowing how we will cope out there; apparently, not well because our cellular systems have evolved on Earth, not in space, as such they -in tune - with Earth's gravity and function -with it. In space, zero gravity is totally alien to our cells and creates unnecessary stress (cells use gravity to function and move around, their DNA blueprint is with Earth setting gravity, they can nagiate in 'spatial space' in the body with gravity; out there in spatial Space Cosmos, gravity is gone, their directional 3D spatial calibration is lost/they have to recalibrate spatially and that's bound to make things work wrong) and as these astronauts fast aging in space when returned to Earth shows. It will be extremely difficult to survive out of Earth, but the more we know the better prepared we will survive; because Have to survive otherwise extinction is next (dinos), if we manage on Earth, everything will be okay and we won't need to leave; but it may needed at some point (Much later on after our own death).

Tardigrades (''Water Bears'') are definitely animals we must study extremely to make sure we get how they survive out there and not suffer cell damage or decalibration/homeostatic balance loss in their system; from the studies it is clear they have oxidative stress mechanisms that we share with; but being simple organisms (while we are complex) makes the whole difference; they can activate HSPs and repair their unfolded proteins like its nothing (they can survive tons of oxidant tests (UV extreme radiation, H2O2, etc), and studies showed, people and animals who live longest have an intact heat shock response HSR and functioning HSPs chaperones (necessary for proteasome/protein chaperoning/lysosomal degradatation of damaged proteins, HSPs are in contact/concert with proteasome and lysosome; are can dramatically protect proteins; in times of stress HSPs (hsp27, hsp70, hsp90...), Metallothionein and HO-1 (heme oxygenase-1) are increased). Tardigrades show that extreme level of oxidative stress protection with special HSPs, it allows them to leave earth, survive out there in space and littarelly come back home like if nothing happened; while us humans astronauts are aging like crazy when back home from stressful space journey). This is also seen in dauer larvae who have DAF-2 signaling pathway and DAF-16 when they enter developmental arrest; yet DAF-2 is directly connected to HSPs activation. During many hibernation or arrest of development, HSPs maintain many things inside from going haywire. In fact, certain seeds of plants have been shown to be maintained in near perfect state for extreme long : the Lotus sacred tree seed (can be grown in flowers from a viable 500 to 1300 years old seed that was conserved inside a hermetic place...studies showed that these seeds's biological mechanisms have powerful HSPs that work during their dormant state and thus can sleep eternally to awaken later as if no time had passed thanks to extreme protein conservation by HSPs; Trehalose is another one (a sugar) and cryoprotectant like HSPs. Same goes on in hibernating frogs or animals, they show either Cold-shock protein maintenance or Heat-shock protein maintenance while asleep. Tardigrades Water Bears tell us something, that we will have to improve these mechanism (thanks to rejuvenation therapy) to make our astronauts survive and make planet colonizing elsewher a realiy in the very far future).

1. http://www.ncbi.nlm.nih.gov/pubmed/19663764
2. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3082643/
3. http://onlinelibrary.wiley.com/doi/10.1111/j.1439-0469.2010.00608.x/abstract
4. https://www.newscientist.com/article/dn14690-water-bears-are-first-animal-to-survive-space-vacuum/
5. http://www.smithsonianmag.com/ist/?next=/science-nature/how-does-the-tiny-waterbear-survive-in-outer-space-30891298/

Posted by: CANanonymity at December 6th, 2015 12:21 PM

CANanonimity wrote:

"Hi Antonio, I understand what you mean. It seems all in vain when our efforts should be redirected towards rejuvenation therapies, on Earth, since it is where we live and most likely will live in 200 years time too."

You misunderstood my message. I didn't even mention rejuvenation. I said that artificial gravity is very easy, so zero gravity health research, apart from the basic facts we discovered half a century ago, is a waste of time and money.

Posted by: Antonio at December 6th, 2015 12:35 PM

There has not been an adequate level of control for the radiation environment, which could also cause changes resembling accelerated aging.

I think it would be worthwhile to create a rotating space station (or station module) that could act as a laboratory for testing a range of (simulated) gravitational strengths on the human physiology (alongside innumerable other purposes). There is no real need for humans to reside in 0g environments for protracted periods, but whether or not humans can thrive under lunar or Martian gravity is a highly pertinent question.

Posted by: José at December 7th, 2015 5:40 PM

José, the radiation exposure of astronauts in interplanetary space is only double than in the Mir or ISS. Radiation danger is hugely overemphasized. No astronaut that has been more than one year continuously in the space stations has had any cancer due to radiation.

The main problem is not background radiation but solar storms. During the storms, astronauts can shield themselves in the storeroom. Water and other consumables will protect them. A layer of around 25 cm of water will suffice.

Posted by: Antonio at December 8th, 2015 12:43 AM

Antonio, you changed the topic of my remark from potential aging-like symptoms (perhaps due to cellular senescence) to cancer. "Astronauts [who] have been more than one year continuously in the space station" is a very small sample size, so I don't think we can definitively pronounce on every type of risk incurred by the radiation exposure. Even high dose exposure can be very unpredictable in its effects. The Goiânia accident provides one of the best illustrations of that, along with the likely overstatement of radiation risks on the whole.

Furthermore, there is no easy way to translate doses of cosmic ray particles to doses of more prosaic kinds of background radiation encountered on the Earth.

Posted by: José at December 8th, 2015 4:11 PM

José: It's not clear-cut yet if DNA damage causes other aging damage apart from cancer (I'm in the camp that says that it doesn't), but my point was that radiation levels are much much lower than what the people advocating for huge radiation shields (or postponement of space travel) think.

"is a very small sample size, so I don't think we can definitively pronounce on every type of risk incurred by the radiation exposure."

The astronauts I mentioned are a small sample, but the measurements of radiation, in manned and ummaned missions, aren't. At all.

"Even high dose exposure can be very unpredictable in its effects."

There aren't high dose exposures, so this is pointless.

Posted by: Antonio at December 8th, 2015 8:53 PM

"Furthermore, there is no easy way to translate doses of cosmic ray particles to doses of more prosaic kinds of background radiation encountered on the Earth."

This objection is more sound. There are more high-energy galactic cosmic rays in space than in the ground. BUT, again, people in the Mir and the ISS received them, and there is no sign of great morbidity increase, whether it's an increase in cancer or acelerated aging. And we have around half a century of space stations data.

Posted by: Antonio at December 8th, 2015 9:04 PM

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