Alzheimer’s Will Limit Human Space Travel

I read a lot of science fiction, as scores have done before me over the past few centuries. I find a galactic setting helpful in engaging with problems of our present world in a way that makes it feel like there is a greater distance, making reflection feel safer. Contrary to readers in the 20th century, space travel for the common person is becoming less like fiction daily as non-astronauts visit the International Space Station, rocket launches are increasingly affordable and renewable, and economies are shifting towards using extraterrestrial environments!

We will visit Mars in person in the coming decades, a months-long trip one-way. As I look forward to playing Bethesda Game Studio’s Starfield after recently finishing all nine books of Iain M. Banks’s Culture series, I think about the plans that incorporate even further destinations. Being a physician-scientist, it is hard not to think of the challenges that come from long-distance travel! While some health concerns of space travel are already reasonably well known, such as muscle deconditioning or the bombardment from cosmic radiation, several conditions have not yet been considered hazards in space travel. This is mainly because the technologies that would make them a reasonable point of alarm for an astronaut have not been invented yet!

Eventually, there will be a way for everything that a human needs to be synthesized onboard a spaceship. Means of accomplishing this are already being investigated, such as through harnessing microorganisms, like bacteria, towards producing everything a human could need, like oxygen, food, and raw materials. As for putting a human in “stasis” for a long journey, artificial hibernation has been academically engaged as a concept, making applications more feasible for the future (although it will take time to evaluate such a procedure due to ethical and safety concerns).

So, let us say that we can keep some humans alive indefinitely in a space shuttle. What else do we need to think of? As a physician and Alzheimer’s disease researcher, I think you can guess one such thing.

Alzheimer’s disease is the most common form of dementia, typically affecting around 10% of individuals older than 65. One’s risk of Alzheimer’s increases as one gets older, with one in three over age 85 having the disease. Alzheimer’s is believed to be caused by the progressive death of neurons, the cells in your brain that contribute to memory and your ability to function.

If I were to jump on a NASA mission right now, travel time to the nearest star system, Alpha Centauri, is a greater concern (130,000 years!). In 2017, NASA proposed a new technology for space travel called solar sails, which could speed this up (44 years). Despite this design remaining a concept and its construction proposed for over 40 years from now (and likely not going to host an astronaut), what would happen if I boarded this vehicle in my seventies and placed in stasis until I arrived?

With every year of traveling, you could count on the risk of developing Alzheimer’s persisting. Unless hibernation technologies find a way to prevent neuronal cell death or the natural deposition of debris in the brain as we age, it is possible that I could wake up having Alzheimer’s! Imagine that, after traveling further than anyone ever had before? While there are “modifiable” risks for Alzheimer’s that could arguably be addressed to reduce the risk of disease, like reducing the risk of blood vessel disease through a healthy diet and exercise, one can only do so much.

One day, we will have to face the music of how we will keep our astronauts healthy on long trips. As with other health conditions, which I will touch on in future articles (be sure to give this article a clap and subscribe), medical research will have to address possible problems arising across body systems rather than a singular goal of having our own intergalactic visitor survive a long trip because there is a lot more to life than simply living, as many of us could agree.

There is reason to be optimistic! In the Alzheimer’s and Aging research fields that I am part of, energy (including mine) and money are going towards finding out how we can help people live longer and better. While science takes longer to yield results than we would like (even AI took decades to develop before it was ready for consumers as ChatGPT), progress is always happening, and getting human life out among the stars is something that people care about.

Let me know your thoughts on prioritizing traveling among the stars! Do you think we should try going as far as possible or focus more on taking it slow?