Faecal transplant can rejuvenate an ageing brain (at least in mice)

Faecal transplants from young mice reverses some age-related traits in the brain of old mice.

Aging affects every part of our body, and research shows that aging is associated with increased levels of inflammation across all systems of the body, including the brain. As we age, we become more forgetful, or it becomes more challenging to learn new things. Now, a new rodent study shows there is some hope to reverse these cognitive declines.

The new research shows that inserting gut microbes from young mice into old mice, using faecal transplants, can reverse the typical effects of aging on learning and memory, as well as certain immune functions in the brain.

“Using a maze, we showed that this faecal microbiota transplant from young to old mice led to the old mice finding a hidden platform faster,” said lead author Prof John F. Cryan, from APC Microbiome Ireland, University College Cork, in Ireland, said in a recent report.

About the study
The gut microbiota is a cosmopolitan group of bacteria and other microbes, found mostly in our large intestine. In the past decades, studies have shown that these microorganisms influence a broad range of functions, from our daily moods to our overall health. And, as we age, so does our microbiota. But, so far, it has not been clear what impact our aging microbiota has on age-related mental declines.

In this new study, researchers wanted to test whether the gut microbiota of young mice could reverse the signs of aging. They took faecal samples from 3- to 4-month-old mice, and transplanted them into 20-month-old mice. The faecal transplants were done through oral feeding, twice a week, for 8 week. As a control, old mice received faecal transplants from old mice, and young mice received faecal transplants from young mice.

One of the key findings noticed by researchers was that the gut microbiota of old mice that received young poop has a microbial composition that resembled the one of young mice. In the brain of these mice, researchers noticed that the hippocampus, a region associated with learning and memory, was physically and chemically similar to the hippocampus of young mice.

In terms of behaviour, old mice fed with young poop also learned to sole mazes faster than the old mice from the control, and were better at remembering the maze layout after multiple tries. None of these improvement in brain function were seen in old mice given old mouse poop.

“It’s almost like … we could press the rewind button on the aging process,” said Prof Cryan in a news report.

However, some things did not change for these old mice with young poop. For example, many gut bacteria remained the same after the faecal transplant, and their social skills did not improve.

Overall, the findings of this new study are encouraging, says Prof Cryan, but more work is needed. “We need to be careful to not over-interpret these findings. We are not advocating faecal transplants for people who want to rejuvenate their brain,” Prof Cryan said.

“Instead, these studies point towards a future where there will be a focus on microbiota-targeted dietary or bacteria-based treatments that will promote optimum gut health and immunity in order to keep the brain young and healthy,” he added.