How Transplants Reverse Brain Aging In Mice

Our brains start to slow down as we age. However, new testing performed on mice indicates that this process may be reversed, but you might not like how. As it turns out, gut microbiomes play a big role in the brain decay process, and replacing old gut microbes with those of younger mice, through fecal transplant, could reverse the aging process in the brain. Luckily, researchers that worked on the experiment believe that a lot more work is required before this technique can be considered safe to use in humans.

Our gut bacteria has a lot of influence over us. It can determine our mood and overall health, and the bacteria changes as we get older. As part of previous studies, researchers found that young blood transplants can rejuvenate elderly mice, but how does changing the gut bacteria of these mice affect them?

To test how microbiome transfer affects aging in mice, researchers transplanted fecal samples from young mice (three to four months old) to very old mice (20 months old). The feces were transplanted using a feeding tube twice a week for two months. For control purposes, some of the old mice received transplants from other old mice.

The first result of the study was that the gut microbiomes of older mice that received the transplant started to resemble that of the young mice. Soon after, changes in the brain started to become apparent. The hippocampus, which is the brain region associated with memory and learning, of the older mice began to resemble that of younger mice from both a physical and chemical perspective. This allowed them to better remember maze layouts and solve mazes faster. These effects were not seen in the control group.

However, the older mice were not fully rejuvenated after the transplant. For example, a lot of their gut microbiome remained unchanged, and they did not become more social, which is a behavior associated with younger mice. On top of that, researchers do not know if the effects were permanent, or if the new gut microbiome is simply temporary. There is also the issue of other studies which have found no improvements after the transplant, and one which actually found that the transplant leads to cognitive decline. One thing is for sure, there will be further studies into this phenomenon and its various effects. For now, human trials are very far off into the future.