“Young Blood” Infusions Helped Mice Brains Function Better & Here's What It Means For Humans

With outré wellness trends becoming A Thing, sometimes it feels like some people will do almost anything to maintain their health. And a new study shows that one of the most out-there treatments may have some scientific backing. Infusions of "young blood" can help mice brains function better, according to the study, and that could mean some very weird things for humans. The study on mice, published in Cell Reports, needs some unpacking, however, before you start signing up for regular doses.

The idea of "younger blood" as an alternative health idea has actually been around for quite some time. It was the opinion of Renaissance doctors that drinking the blood of the young could sustain the elderly, to the point where Pope Innocent VII, on his deathbed in 1492, was reportedly given three young boys' blood to keep him alive. (It did not work.) One of the most famous serial killers in history, 16th-century Hungarian Countess Elizabeth Báthory, was renowned for drinking the blood of young victims with the idea that it would keep her youthful. It's from the legends of Báthory and similar tales that Bram Stoker would take his inspiration for the story of Dracula.

The idea of young blood as a health trick has turned up in the mix of alternative medical treatments in recent decades. A private clinic in California, it was reported in 2017, offers a transfusion of young blood in pursuit of youth and beauty for a cost of $8,000. And Slate noted in 2017 that blood transfusions of this kind are "the new healing crystals" among a particular sub-set of entrepreneurs and hyper-wealthy patrons: a niche interest, but with little actual science behind it. Now, however, the new data discovered by the University of California scientists behind this blood study may be giving some actual scientific backup to the blood-transfusion idea — though in ways that are slightly unexpected.

The scientists used a technique straight out of science fiction called "parabiosis," in which the circulatory systems of old and young mice became linked. And after they'd been exposed to a good quantity of young blood, the older mice exhibited higher levels of an enzyme called Tet2. Tet2 is linked to the degeneration of certain brain functions as we age; the less of it we have, the worse our memories seem to get. And the brain levels of Tet2 in the older mice spiked, indicating that they were receiving a neurological boost from young blood.

To test what Tet2 actually does in the mouse brain, the scientists checked what happened with too little and a lot of Tet2 in the brains of young and old mice. Too little, and they lost their way in mazes and couldn't do simple tasks. A lot, and their memories improved, particularly if they were older. It's pretty clear that Tet2 levels are highly linked to good brain function, and that, for unknown reasons, something about exposure to young blood improves their levels in mice. How that works remains unknown.

What works on mice, though, may not work on humans. The effects of "young blood" on human brains and levels of Tet2 will likely be different; humans and mice are similar in some ways and different in many others, notably in the category of brain size. We have about the same brain-to-body-size ratio as mice, but ours are a lot bigger, of course, and would probably respond to the influence of new blood in different ways — that is, if the concept is ever approved to test on humans. While the new mouse science is certainly interesting — and, let's face it, creepy as hell — it doesn't mean that this practice has any true health benefits, especially for humans.