Scientists are finding more evidence that gut health plays a big role in how the brain ages. A new study suggests that altering the gut microbiome and stimulating a key nerve linking the gut and brain might help reverse memory loss associated with ageing.
The study, led by scientists at Stanford University and published in the journal Nature, examined how the gut microbiome, the community of bacteria in the digestive system, changes with age.
Senior author Christoph Thaiss said the goal was to find out why some older people maintain strong cognitive function while others begin to lose memory in their 50s or 60s.
The researchers found that memory decline doesn’t have to follow a set timeline. Instead, it might be affected by biological processes in the body, especially in the digestive system.
A key part of the study focused on the vagus nerve, which sends signals between the gut and brain. Changes in the gut microbiome can trigger immune responses in the digestive system, leading to inflammation.
This inflammation weakens the signals travelling through the vagus nerve to the hippocampus, the part of the brain that handles memory and navigation.
When communication breaks down, memory can worsen.
What Scientists Observed in Experiments
The researchers used mice to study how gut bacteria affect thinking skills. They saw that older mice had different gut microbiomes than younger ones.
One type of bacteria, Parabacteroides goldsteinii, was more common in older mice and was linked to worse memory.
When scientists added this bacteria to younger mice, the mice did worse on memory tests like recognizing objects and finding their way through mazes. Brain activity in the hippocampus also dropped.
The most surprising finding came when researchers stimulated the vagus nerve in older mice using a specific molecule. After treatment, the older animals showed memory performance similar to that of younger mice.
In maze and object recognition tests, the forgetful mice suddenly did much better, suggesting the gut-brain communication had been restored.
Researcher Maayan Levy said the findings show how brain function can be affected by changes outside the brain.
Scientists think targeting the gut microbiome could be a promising way to treat age-related memory loss. Since the digestive system is easy to reach, treatments might one day adjust gut bacteria through diet, medicine, or other methods.
However, this study was done in animals, so more research is needed before similar treatments can be used in people.
Still, these findings add to what we know about the gut-brain connection, suggesting that keeping a healthy gut is important not just for digestion but also for long-term brain health and memory.
