Young Bacteria Restore Brain Adaptability in Older Mice

In June 2026, Chris Simms wrote about a new study. Scientists in Italy studied the gut microbiome of mice. The gut microbiome is the collection of bacteria in the stomach. These bacteria can affect the brain in many ways.

Young brains can change and adapt very easily. Medical scientists call this special ability brain plasticity. The brain has high plasticity in childhood, but it decreases during adolescence.

First, researchers gave young mice a strong mix of antibiotics. They dissolved the medicine in their drinking water for ten days. These experimental mice were only twenty-one days old.

The antibiotics changed their gut microbiomes in a bad way. The treatment reduced good bacteria, such as Lachnospiraceae. These bacteria produce healthy chemicals for nerve cells.

Then, researchers closed one eye of each mouse for three days. After that, they looked at the brain responses of the mice. Only the control mice showed normal brain plasticity. The brains of the treated mice did not change.

Next, they examined the active genes in the visual cortex. The researchers found changes in more than one thousand genes. Some genes control the protective cover of nerves. Other genes control the barrier between the blood and the brain.

Finally, the scientists transplanted gut bacteria from young mice. These young donor mice were thirty days old. They gave these young bacteria to older mice. These older mice were already four months old. Another group of adult mice received transplants from older donors.

The researchers closed one eye of these adult mice. Only the mice with young bacteria showed brain plasticity. The brains of the other group did not change.

Scientists in Norway and Ireland discussed these results. They think the microbiome might help the brain recover from injuries. However, we cannot apply this research directly to humans yet. This is because human brains are much more complex.