The Path to Better Mental Health May Be Through Your Stomach

Researchers at the University of Virginia School of Medicine have discovered how Lactobacillus, a bacteria found in fermented foods and yogurt, helps the body manage stress and may help prevent depression and anxiety.

Their study is published in the journal Brain, behavior and immunity. The findings open the door to new therapies to treat anxiety, depression and other mental health problems.

Alban Gaultier, researcher at UVA, and his collaborators say that this discovery is remarkable because it identifies the role of Lactobacillus, separating them from all the other microorganisms that live naturally in and on our body.

These organisms are collectively known as the microbiota, and scientists are increasingly looking to target them to fight disease and improve health. UVA’s new research represents a major advance in this effort, providing scientists with an innovative new approach to understanding the role of each microbe that could help develop new treatments and cures for a variety of illnesses, both mental and physical.

“Our discovery sheds light on how gut-resident Lactobacilli influence mood disorders by adjusting the immune system,” said Gaultier, of UVA’s Department of Neuroscience, Brain Immunology Center. and glial and the TransUniversity Microbiome Initiative. “Our research could pave the way to discovering much-needed treatments for anxiety and depression.”

Microbiota and depression

Our intestines are naturally home to countless bacteria, fungi and viruses. There are more microorganisms living in and on us than there are cells in our body. It may sound disgusting, even alarming, but scientists say these tiny organisms and their interactions are essential to the immune system, health, mental health and other facets of well-being.

Disruptions to the microbiota, whether due to disease, poor diet, or other causes, are known to contribute to many diseases and even contribute to the spread of cancer. Thus, researchers have been very excited in recent years by the possibility of fighting diseases by targeting the microbiota.

Early attempts to manipulate gut flora with beneficial bacteria, called probiotics, produced mixed results. Much of the problem lies in the complexity of the microbiome, which is estimated to comprise 39 trillion microorganisms. Trying to understand what specific bacteria or fungi do – let alone how they interact with all the other microorganisms and their host – can be like trying to count grains of sand on the beach.

Gaultier and his team took an innovative approach to focus specifically on lactobacilli. Previous research from Gaultier’s lab suggested that the bacteria could reverse depression in lab mice, an extremely promising finding. But researchers needed to figure out how.

“We knew from our previous research that Lactobacillus was beneficial in improving mood disorders and was lost following psychological stress, but the underlying reasons remained unclear, mainly due to the associated technical challenges to the study of the microbiome.”

Gaultier and his team decided to continue their research into depression using a collection of bacteria, known as the “modified Schaedler flora,” which includes two strains of Lactobacillus and six other bacterial strains. Using this rarely used bacterial community, the team was able to create mice with and without Lactobacillus, avoiding the need for antibiotics.

The modified Schaedler flora produced exciting results. Gaultier and his colleagues were able to explain exactly how lactobacilli influence behavior and how the lack of bacteria can worsen depression and anxiety. Lactobacilli from the Lactobacillacea family maintain levels of an immune mediator called interferon gamma that regulates the body’s response to stress and helps prevent depression.

Armed with this information, researchers are ready to develop new ways to prevent and treat depression and other mental health conditions in which Lactobacillus plays an important role. For example, patients suffering from depression or at risk of depression might one day take probiotic supplements specially formulated to optimize their levels of helpful Lactobacillus.

“With these results, we have new tools to optimize the development of probiotics, which should accelerate the discovery of new therapies,” said researcher Andrea R. Merchak. “More importantly, we can now explore how maintaining a healthy level of Lactobacillus and/or interferon gamma could be studied to prevent and treat anxiety and depression.”

The research team included Merchak, Samuel Wachamo, Lucille C. Brown, Alisha Thakur, Brett Moreau, Ryan M. Brown, Courtney Rivet-Noor, Tula Raghavan and Gaultier.