If you read the medical reporting online you can become convinced that we will soon be living like the fictional marvel comics character Blade, “Day Walker”. An immortal that needs human blood to keep himself/herself rejuvenated. They give the mostly false impression that recent research is the first step to immortality. Although there is recent research, confirming prior evidence, of a benefit to older mice from younger mice blood. This is by no means the “key” to immortality. That has not prevented any news media outlets from reporting that it is age reversal in mice. Nor has it stopped them from extrapolating the same benefit to humans.
That may sound familiar since this is a common pop culture theme and has some historical precedent as well. There are early documented references to the use of blood, for what can be at best described as ‘medicinal’ purposes. One of the first of these relating to a ‘transfusion’ is contained in the seventh book of the Metamorphoses, by Ovid, who wrote in 43BCE, describing how (the witch) Medea rejuvenated Jason’s aged father Aeson as follows:
“Medea took her unsheathed knife and cut the old man’s throat letting
all of his blood out of him. She filled his ancient veins with a rich elixir.
Received through his lips and wound, his beard and hair no longer
white with age, turned quickly to their natural vigour, dark and lustrous;
his wasted form renewed, appeared in all the vigour of bright youth“.
Almost 2000 years of scientific advancement cannot stop current science reporters from falling for the same story.
Here are just a few of the dramatic headlines you can find online…
- Young Blood Restores Old Mice
- Swapping Young Blood for Old Reverses Aging
- (My Personal Favorite) Vampire’ blood transfusions could cure Alzheimer’s and even be the secret to eternal youth
Could this possibly be true? Is there immortality in the blood freezer at the local blood bank? Well the short answer is……aaaaah no!
These articles are an exaggeration of the salient facts, married to a misunderstanding of a complex science. Small exaggerations allow writers to produce an attention grabbing sound bite and/or headline.
Eternal youth from blood is an irresistible story for both the writers and the readers. Realistically, it as a unsupported conclusion based on some recent research. Lack of probablity does not seem to prevent science reporters from promising eternal youth or pop culture fictional imaginings like vampires.
The actual research makes much smaller claims; although the principal investigators have taken full advantage of pop culture imaginings to promote their research (this is becoming more and more common in promoting research and unfortunate in my opinion).
The actual research is actually three separate lines of good evidence.
- Young blood reverses age-related impairments in cognitive function and synaptic plasticity in mice.
- Vascular and Neurogenic Rejuvenation of the Aging Mouse Brain by Young Systemic Factors
- Restoring Systemic GDF11 Levels Reverses Age-Related Dysfunction in Mouse Skeletal Muscle
The most recent paper Number #1 is making the rounds in the news. Injecting old mice with blood from younger mice improved their cognitive abilities along with promoting new neuron growth in their spinal cords. This is a further line of evidence that some factor in blood keeps regenerative processes going for a time, but then disappears with aging. The older research done by the same group at the University of California San Francisco (UCSF) and Stanford University in Stanford, Calif., can be found in the journal Nature Medicine. That research involves “heterochronic parabiosis,” which connects the vascular systems of young and old mice so that the young animals’ blood circulates through the older animals. That research had also demonstrated a systemic rejuvenation effect. However, it is still not certain whether GDF11 is the factor underlying these findings.
Multiple lines of convergent evidence in medicine is usually very convincing. As you may have guessed, this evidence is magnitudes removed from being able to make the types of conclusive statements present in the media reports.
The research is duplicating an effect but the conclusions are at best a stretch. There are many factors that are not being controlled for. Even if you assume that the conclusions are 100% accurate there is no guarantee that this effect automatically transfers to humans.
For example, there is a list of studies showing successful spinal nerve regeneration with stem cell treatments in rodents. Everyone is trying to find a way to regenerate the spinal cord after an injury. Despite tons of limited success in rodents it just doesn’t work in other animals especially humans. It is well known that rodents have regenerative properties that we just don’t share. The stem cell treatments just don’t seem to translate to humans like they do in rodents. A common flaw in the conclusions “is it the rodent or the treatment”. It is very likely that this research will run into the same “Human Barrier”. We are not rodents and what works for them doesn’t commonly work for us.
The GDF11 factor is significant because we share this factor with rodents. In truth the researchers have failed to properly isolate this factor. So is the effect from the factor or is it something else?
Additionally there are many many confounding factors. Could it be some hormonal factor in the blood, or something specific to mice in general.
Finally plausibility is an issue for this conclusion. Blood transfusion has been around since 17th century, it is not new med. tech. If there was a large effect from youthful blood transfusion it would have been noted. I am sure since this has been a consistent folk legend surrounding blood. I am certain that real or not it would have been noticed given the millions of blood transfusions that have taken place. More damaging to plausibility is the totality of what we know about the aging process. There is no one factor. Aging is multi-factoral and it is far too complicated of a process to be blunted by one particular blood factor.
I think that the research is worth pursuing. That said, when you evaluate this using a Bayesian model you will see that it is highly unlikely that GDF11 will be a panacea for eternal youth, never mind a cure for Alzheimer disease.
Like many science/medicine stories this news cycle is another good example of why science writers need to consult experts before writing stories. Headline editors are good at writing headlines but they are lousy journalists with absolutely zero science chops.