A transfusion of 'old' blood might make you age more quickly

In M. Night Shyamalan’s latest film, Old, a diverse set of characters are vacationing at a tropical resort when they receive an exclusive invitation to visit a private beach. When they arrive, they walk through a narrow canyon and emerge to a quiet beach with only a couple of other parties present. Everything seems as it should until… spoiler alert… one of the elderly attendees suddenly dies and the young children sprout into teenagers before our very eyes.

Despite all logic, the beach appears to be a horrifying corruption of humanity’s long search for the fountain of youth, a body of water which imbues anyone who swims in or drinks it with extended or eternal life.

Of course, while the fountain of youth and its many derivations – philosophers’ stones, elixirs of life, and what have you – have failed to reveal themselves, scientists have taken the search into the laboratory in the hope of understanding the biological mechanisms at play in aging. The thinking goes that by understanding them, we might be able to slow down, arrest, or even reverse them.

Among the wackier ways in which people throughout history have attempted to stave off aging and death is the use of “young” blood. There are even relatively recent accounts of elderly individuals injecting the blood plasma of younger donors in an effort to delay the reaper. The trend was significant enough that the FDA stepped in with a warning, noting that there is no known clinical benefit while there are potential risks.

Still, there is some scientific interest in the potential effects of certain blood characteristics on the process of aging. To settle the question once and for all, or at least extend our knowledge in this arena, scientists in Kyiv, Ukraine and Haining, China took blood sharing to its extreme using mice. The results of their study were published in the journal Rejuvenation Research.

It stands to reason that if there is any measurable effect from a transfusion or injection of blood, then that effect should be highlighted with even more blood. At least, that’s the idea behind the truly bonkers experiment researchers carried out. In the lab, scientists surgically connected two mice, one young and one old, such that they shared a single circulatory system. The process is known as heterochronic parabiosis and, shockingly, isn’t all that new.

The process of surgically connecting two organisms dates back at least 150 years and the specific version of the procedure wherein a young and old organism are connected is only a little more recent. Despite conjuring feelings of mad scientists in their secret villainous lairs, the practice has led to advances in a number of biological fields, including the studies of the immune system and cancers.

For this study, the paired mice were left connected to one another for three months, after which they were disconnected. Then scientists investigated to see if the older mouse might have extended longevity or reduced aging as an effect of the younger mouse’s blood. In essence, are the claims that young blood can revitalize the elderly supported by the evidence?

In short, no, and that’s not all.

Scientists found no significant impact on the longevity or process of aging in older mice. Moreover, they found a negative effect in younger mice. According to the researchers, they observed a significant decrease in the lifespan of young mice, which suggests that old blood contains some characteristic capable of inducing aging in younger individuals. The opposite appears not to be true.

If they had seen both effects – the old mice getting younger while the young mice got older – you could almost understand the basis of the myth. One can imagine a powerful elderly person sucking the life out of their youthful companion in order to extend their reign upon the Earth like some sort of high-tech modern vampire. Reality, however, isn’t quite so poetic. Sharing blood is a net negative. You can only lose or draw.

In a final twist from reality, while sharing blood won’t make you younger, sharing poop just might. So, the next time someone tries to steal some of your blood, tell them you have a counteroffer they won’t be able to refuse.