It turns out, having a healthy gut can make you “fear less”

A study led by Weill Cornell Medicine in New York City has shown that a healthy gut can make you “fear less” by extinguishing your fear memories. In an article published in the journal Nature, the researchers detailed how they used mice to explore the ability to unlearn fear responses.

Exploring the gut’s role in fear response

It has become increasingly evident that gut bacteria play an important role in brain health. Previous studies showed that disruption to these microbial communities is linked to behavioral changes and certain autoimmune and psychiatric disorders.

For example, a recent study showed that a certain combination of gut bacteria exacerbates symptoms of multiple sclerosis, a brain and nerve disease. In another study, researchers found that children with inflammatory bowel disease (IBD) are at higher risk of developing psychiatric disorders, such as depression and anxiety, later in life.

But though these investigations were able to confirm the existence of a gut-brain axis, the mechanisms that underpin this axis remained unclear.

“No one yet has understood how IBD and other chronic gastrointestinal conditions influence behavior and mental health,” said co-senior study author David Artis, a professor of immunology and director of IBD research at Weill Cornell.

For their study, the researchers focused on how well mice would learn and forget a fear trigger using an experiment called “fear conditioning and extinction learning.” In this experiment, the mice are conditioned to associate a threat with the sound of a tone, so that the tone by itself can elicit the same fear response as the threat.

The mice tended to forget the association after repeated exposure to the tone, as their brains adjusted to the fact that the threat no longer exists. But the mice whose guts were germ-free from birth or whose gut microbes were vastly reduced, showed a significant reduction in their ability to learn that the threat was no longer present. This means that their brains were not updating to the new conditions.

Mechanism behind gut’s effect on fear memories

MedicalNewsToday.com

ScienceDaily.com

Healio.com