Older people

Could young blood 'slow' ageing?

“Vampire treatment with young blood reverses ageing process,” The Independent reports. But before you get too excited, we should clarify that the headlines relate to a study on mice.

The research involved connecting the circulation of young and aged mice, to discover how this affected the area of the brain involved with learning and memory. It was found that young blood rejuvenated some communication between nerve cells in the mice.

The researchers then tested whether injecting old mice with blood from young mice improved thinking processes, by examining their performance in a water maze. These treated mice learnt and remembered how to escape the maze better than the other mice in the study.

This was very early-stage animal research and may not have any human implications, contrary to some of the media headlines. Injecting older humans with young blood may not reverse brain ageing or halt the progression of degenerative conditions, such as Alzheimer’s disease. However, it will be interesting to discover which components of blood caused the rejuvenation in these mice.

This study adds to the existing body of research on the ageing process and potential treatment strategies, with further study likely.

Where did the story come from?

The study was carried out by researchers from the University of California, San Francisco, and other research and health care organisations in the American state of California. Funding was provided by numerous research fellowships.

The study was published in the peer-reviewed scientific journal Nature Medicine.

In general, the human implications of this research have been over-stated, with the Daily Express saying that: “Older people with Alzheimer’s disease could one day have their brains ‘recharged’ by pumping young blood into them”. This is very premature, given that this was early-stage animal research.

What kind of research was this?

This was a study examining whether exposing an aged animal to blood from a young animal could reverse brain ageing.

Ageing causes structural and functional changes to the brain, which can alter thinking processes. Ageing is also associated with a susceptibility to degenerative disorders, such as Alzheimer’s. 

Previous animal studies have shown that injecting blood from a young animal into an older animal improves the function of stem cells in muscles, the liver, the brain and spinal cord. However, it is not known whether the effect of young blood to the brain could extend beyond this and rejuvenate thinking processes. This latest study aimed to fill the gap in research.

What did the research involve?

This animal research first involved connecting the circulation of young and aged mice, and looking at the structural effects this had on the brain. They then tested the effect of injecting aged mice with blood from young mice on thinking processes, by looking at fear conditioning, spatial awareness and memory.

The researchers first examined which genes were active (gene expression) in samples of the hippocampus (a brain region involved in memory and known to be vulnerable to ageing) from 18-month-old mice. They compared this with the gene expression of similar mice that had had their blood circulation joined with another aged mouse, or with a young mouse.

In particular, the researchers were looking at changes in gene activity that might indicate that the nerve cells in the aged mice’s brains were showing signs of behaving more like younger nerve cells.

They carried out further analysis of joined mice to look at whether structural changes were underlying any changes in nerve communication.

The researchers speculated that exposure to young blood could similarly enhance thinking processes. They therefore took a separate group of 18-month-old mice and injected them with blood plasma (i.e. the liquid component of the blood, not including the actual blood cells), over a three-week period, from either young (three-month-old) or similarly aged mice. They then examined their performance in a water maze.

What were the basic results?

Aged mice that had had their circulation joined with young mice showed signs of rejuvenation in how the nerve cells in the hippocampus behaved and communicated. Genes involved in the ability of the nerve cells to adapt (part of the learning process) became more active than they normally would at that age.

When looking at what structural processes related to these changes they found that, in a certain region of the hippocampus, there was an increase in the number of protrusions on the ends of the nerve cells that receive signals from other nerve cells.

When testing the effects on cognitive processes, they found that aged mice injected with young blood could learn and remember the location of underwater hidden platforms in a water maze test better than those that hadn't. Those injected with young blood also demonstrated increased freezing responses during fear conditioning training. Aged mice injected with blood from other aged mice showed no differences from aged mice who were not injected.

How did the researchers interpret the results?

According to the researchers, this study indicates that exposing aged mice to young mouse blood can counteract some of the molecular, structural and cognitive effects of ageing on the brain.


This research is of scientific interest, as it demonstrates how linking the circulation of aged animals with young animals can lead to “rejuvenating” changes in nerve cells in a region of the brain involved with learning and memory. The molecular and structural effects seemed to extend into thinking processes, whereby aged mice performed better both in a water maze test and a fear-inducing event.

What the cause of these changes could be is not understood. As the researchers suggest, it is possible that young blood contains “pro-youthful” factors that can reverse age-related impairments in the brain, or counteract “pro-ageing” factors. Further research is needed for greater conclusions to be drawn.

This very early-stage animal research has no direct human implications. It is too great a leap to suggest that injecting older humans with young blood would have any effect on reversing brain ageing or halting the progression of degenerative diseases, such as Alzheimer’s. There are mouse models of Alzheimer’s disease, and the next step may be assessing if this approach has any effect on these mice.

Even if further human studies suggested that young human blood could have an effect on human brain cells, there would be many things to consider if this was to be a treatment for humans. Not least of these are the ethical considerations.

It is much more likely that research will continue into why this effect is seen, and working out if it can be replicated without the need for a blood transfusion.

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