A faulty connection between the gut and the brain can damage memory

We share this report from Agencia SINC about a new study in mice that reveals how changes in the digestive system influence cognitive decline and points to possible avenues for intervention, such as vagus nerve stimulation or microbiome restoration using antibiotics.

El memory impairment can begin in the digestive systemThis has been confirmed by an experiment with mice in which researchers have found that gastrointestinal inflammation and the changes it entails are a direct factor in cognitive impairment.

The magazine Nature This week, a study by an international team of researchers from American and European centers was published, which could partly explain why some people of the same age experience more memory impairment than others.

The discovery identifies a three-stage pathway to memory loss. The first change occurs with gastrointestinal aging and the subsequent microbial and metabolic alterations.

Myeloid cells in the gut detect these changes and their inflammatory response impairs the connection between the gut and the brain via the vagus nerve.

The good news is that researchers have found in mice that restoring vagus nerve activity also restores memory function: an old animal can return to levels typical of a young one, an observation that opens up promising prospects for future treatments.

Vagus nerve stimulation in humans is, in fact, already approved in many countries to treat the symptoms of diseases such as epilepsy.

“Our hope is that, ultimately, These findings can be translated into clinical practice"To combat age-related cognitive decline in people," says one of the authors, Christoph Thaiss, from the Arc Research Institute of California.

Experiment

To test their theory that gut microbiota influences brain aging, the researchers housed young mice (2 months old) alongside old mice (18 months old). By living and defecating together, the young mice were exposed to the gut microbiota of the old mice, and vice versa.

After spending a month together, the researchers examined the composition of the microbiomes of the old and young animals. They discovered that sharing space made the microbiomes of the young animals more similar to those of the older animals.

When comparing the mice's ability to recognize a novel object or find their way out of a maze, the young ones with aged microbiomes performed poorly on these tests, just like their older counterparts.

However, when rrestore your microbiome using antibioticsThe effect was reversed and the mice recovered juvenile levels of cognitive function.

A key bacterium

Meanwhile, germ-free mice showed slower cognitive decline with age, compared to normal mice with microbiomes typical of aging, supporting the existence of some component of the aging microbiome that drives memory loss.

The authors believe that component is the bacteria. Parabacteroides goldsteiniiIts production increases with age and causes inflammation that disables the functions of the vagus nerve and contributes to cognitive decline.

If they colonized the intestines of young mice with this bacterial species, the mice lost abilities in object recognition and maze escape tasks.

However, when they treated the old mice with a molecule that activates the vagus nerve, the cognitive performance of the animals proved indistinguishable from that of the young specimens.

“Our work demonstrates that the proper signaling from the gut to the brain"Through the vagus nerve, it protects mice against age-related cognitive decline," the authors emphasize.

Source: SINC Agency