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Unorthodox gut study reveals poop may be able to reverse ageing in the brain

By Francesca Johnson

Nov 28, 2021

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What I’m about to tell you is a story of mice and men, but not quite the way John Steinbeck envisioned it. No, unlike your English class, the musing currently sitting inside my skull is definitely part of the hear-me-out variety. My thought goes like this: when my future children are looking at old folks’ homes for me, maybe I’ll be wishing I got my intestines pumped with the excrement of a teenager.

Now, stay with me—I’m begging you—because I’m talking about a new scientific innovation here. And yes, for once, it is as weird as it sounds. That’s right, the future includes… faeces. Who would’ve thunk it? Well, scientists have long known about the secret strength found within the metropolis of trillions of bacteria in your tummy. Known as the gut microbiome, this goldmine is also central to mental health, the immune system, and more. And now, an unusual study has opened the door for a mind-blowing new strategy for researchers to turn back time and reverse ageing in the human brain.

Published in the journal Nature Aging in October 2021, research indicates that bacteria in young people’s poop could be the key to the, as of now, unavoidable shrinking of the brain. Before you click off in horror, allow me to explain how the team behind the research stumbled upon this incredibly odd discovery.

Although Jeff Bezos has been on the quest for immortality for quite a while now, most of us don’t think about brain ageing at all. Our society is unfortunately focused on the more cosmetic threats to our finite existence. Not everyone is eager to start looking older, contrary to what our love for vintage fits seems to say about us and gen Z’s affinity with disposable pictures. We are constantly spinning the wheel with our body image and appearance as we age, but god forbid we ever end up looking old. Imagined wrinkles and insecurities around laugh lines dominate conversations and common knowledge around anti-ageing. The results of this have led to some extreme efforts to keep our clutch on youth close, from vampire facials to baby Botox.

But let’s forget physical appearance for a minute. I think the most I’ve done to combat the inevitable decline in my abilities was to play a few rounds of brain training aged 10, feigning surprise when I got any age under 65. But what will happen when I’m actually 65, and it might be too late? Unlike with our skin, there is no magic cream to slap onto your skull in an attempt at reversing the ageing of the human brain. Your brain health is probably a lot more important to keep track of since a shrinking brain—which happens as you get older—can negatively impact your thinking, learning and memory. Being a brain teaser buff and stocking up on your sudoku puzzles can delay cognitive decline but, unfortunately, none of us is Peter Pan and the cost of growing up is entropy.

First of all, let me start by clarifying one thing: this research is not the fountain of youth or anything—though for some fulvic acid might be. The research has found that older mice, when given gut bacteria transplants from younger mice, show learning and memory abilities similar to those of the younger rodents. To put it plainly, a cocktail of gut goop—or “poo transplant” as co-author John Cryan told Inverse—appeared to reverse some of their brain’s decline.

Researchers transplanted faeces from three-to-four-month-old rodents into the intestines of 19 or 20 month-old mice to cultivate a similar gut microbiome. On a human scale, this would be like taking the ripe poop of an 18-year-old and transplanting it into the body of a 70-year-old. Pretty grim mental image, yet pretty impressive possibilities, right?

In the old mice, the transplanted faecal bacteria seemingly promoted the growth of gut microbiota resembling the younger mice’s microbiome. The results of the study found that the mice who had the faecal transplant were able to reach a specific goal with greater success than mice without it. This indicates that certain gut bacteria could influence cognitive functions, which tend to decline in efficiency over time as organisms get older.

Like a new lease of life, the older rodents’ spatial memory—which holds information needed to plan routes—changed following the transplant using a simple test called the Morris water maze. The older mice, both with and without the faecal transplant, were placed in a water maze that required them to use their spatial memory to plan and follow a path in order to get to a dry platform.

After saying RIP to the research-rat-pack and decapitating the rodents, researchers looked inside the brains of the older mice to see if their behavioural improvements were reflected in their neurobiology. They found that the old mice’s hippocampus—a brain region responsible for memory—resembled that of younger mice.

Marcus Böhme, a neuroscientist with University College Cork (UCC) and one of the authors of the study, shared with Inverse, “It was really great to see that full change in their microbiomes can really excel such effects on cognitive behavior, like almost resembling the learning performance of young mice, it was pretty mind-blowing.”

I, like many others, yearn for that happy-go-lucky state of mind. The appeal of it lies within being free and childlike, a desire that has previously pushed many on TikTok to try to talk to their younger selves. Grappling with our short time on Earth is difficult to say the least. In order to understand how much of a medical marvel this research is, we need to take a step back and see the bigger picture here. Our brains are as beautiful as they are complex. Many areas orchestrate complicated cognitive processes, such as problem-solving, memory, judgment, and language.

At the centre of a lot of these processes, is the frontal cortex of your brain. Think of it as the command control of all your brain’s networks which takes care of managing everything that has to do with learning and memory processing. As mentioned earlier, the helpful hippocampus works to form and store memories. However, as we age, these regions slowly start to shrink.

Age is a bummer, in more ways than one since ageing also entails the decreased production of the dream team of chemical messengers in the brain—dopamine and serotonin. These are some of the many reasons for older adults’ forgetfulness, trouble remembering names, and inability to multitask. Or the age-old mystery affecting every adult alive, the one that not even Sherlock Holmes could crack: the case of the pesky missing keys.

Now, don’t get excited just yet, as even the researchers behind the study assure that it only represents a new insight into how the human brain works. And these latest results actually fall in line with what we already knew about our trusty guts. For example, another study—completed by researchers at the Keio University School of Medicine in Tokyo—published earlier this year in Nature, found that people who live to be older than 100 have a specific set of gut microbiomes that could potentially shield us against age-related diseases and infections.

Research into the special bacterial strains gets us closer and closer to creating anti-ageing treatments for the future. Until then, try to realise that you don’t need a young brain to be young yourself. I’m just saying, it’s never too late to get that lower back tattoo.