It's not just our body that breaks down with old age. Inevitably, the effects of aging hit the brain as well, affecting our cognitive abilities to remember and pay attention to things. However, just like a good skin routine can minimize wrinkles on the face, there are methods to stave off cognitive decline from aging. Besides keeping the mind sharp with intellectual activities like playing chess or reading ZME Science, one particularly outlandish method could prove to be transplanting fecal matter from younger individuals. This is not satire.
In a recent study published in the journal Nature Aging, neuroscientists at University College Cork in Ireland transplanted the poop of 3 to 4-month-old mice into the intestines of 19- to 20-month-old mice. The age difference is equivalent to that between 18-year-old and 70-year-old humans.
After some time, the transplanted fecal bacteria colonized the guts of the elderly rodents, growing and expanding until the microflora of the young and old mice resembled each other.
To see how the gut microbes may have affected the brain, the researchers placed the mice in a water maze, which challenges them to plan an escape route. Older mice that received a fecal transplant found the escape platform quicker and with greater odds of success than old mice with the same old poop. They also remembered the escape route just as well as younger mice.
John Cryan, a neuroscientist at University College Cork and lead author of the new study, claims that the results can be explained by the altered rejuvenated microbiome, with research over the past decade showing it plays a major role in brain function. Previously, Cryan's team showed that introducing a specific strain of Lactobacillus bacteria into the guts of mice reduces levels of the stress hormone corticosterone and reduces anxiety and depression.
The effects of the poop transplant could also be seen in the brain's physiology. When the researchers examined the brains of older mice they found that the hippocampus -- a region of the brain associated with forming and storing memories -- resembled that of young mice. Essentially, the fecal transplant helped reverse neurodegenerative effects in the brain.
“This study is really a kind of proof of concept. It’s the killer experiment,” Cryan told The Scientist. “If the microbiome is playing a causal role in brain aging, then we should be able to take the microbiome from young animals, give it to old animals and reverse or attenuate some of the effects of aging.”
The big takeaway is that the microbiome may be far more important for brain health than previously imagined, especially as we age. As a caveat, this study was conducted solely on male mice, and the results may not carry over to humans. But there are good reasons to believe they could. Previously, scientists found that children with autism spectrum disorder (ASD) who received a fecal transplant experienced a 45% reduction in core ASD symptoms (language, social interaction, and behavior).
Perhaps it is now time to conduct a study examining the cognitive effects of poop transplants in humans, too. Who's up for it?