ARI SHAPIRO, HOST:
What makes a person resilient to stress? Scientists at UCLA believe some clues can be found in the relationship between their gut and the brain. Here's NPR's Will Stone.
WILL STONE, BYLINE: This type of research on the gut microbiome, made up of trillions of tiny organisms, often explores how it may influence diseases and psychiatric conditions like depression. So for this latest study, neuroscientist Arpana Church decided to shift the focus. She looked at healthy adults without a mental health diagnosis.
ARPANA CHURCH: What is it about those individuals who do experience stress but do not develop disease?
STONE: She and her team at UCLA separated 116 adults into two groups based on a psychological scale of resilience. There was a high-resilience and a low-resilience group. Then they analyzed an enormous amount of data collected from brain imaging, stool samples and questionnaires.
CHURCH: The accuracy with which these patterns emerged was really amazing.
STONE: In the brain, they looked at the structure and connectivity of different regions.
CHURCH: Think about the cognitive part or the frontal part of your brain, like, being the brakes. The highly resilient individuals had really efficient brakes. There was less of this hyperstressed response.
STONE: Then there was the gut microbiome, where they found microbial signatures that distinguished those with higher resilience.
CHURCH: The pattern was that they were related to anti-inflammation, and they were related to better gut barrier integrity.
STONE: Which are features of a healthy microbiome. Church says her study, published in the journal Nature Mental Health, lays the groundwork for human trials. For example, they can target the brain with certain therapies to see what happens in the microbiome, or they can use diet, maybe probiotic supplements, and track the effect on the brain.
CHURCH: We need more studies that are actually going to test these in human trials and say, like, OK, this is what's causing the changes.
STONE: In recent years, scientists have made big strides establishing the link between the brain and the microbiome in our gut, the fact that communication goes back and forth.
THOMAZ BASTIAANSSEN: We're now leaving the infancy stage of the microbiome field.
STONE: That's Thomaz Bastiaanssen at Amsterdam University Medical Center.
BASTIAANSSEN: We have really robust evidence it's there. Now the next question is, we need to understand, how exactly does it work?
STONE: Of course, this is quite difficult, given the complexities in the microbiome, which is its own ecosystem, and the field of mental health.
BASTIAANSSEN: So on both sides, it's like - we have a tenuous grasp.
STONE: Research does suggest this interaction between the gut and the brain happens in a variety of ways. A major one is the vagus nerve, a sort of superhighway. Then there's the immune system, which is very active in the gut. Also, neurotransmitters like serotonin get produced down there.
Plus, the microbiome secretes what are known as short-chain fatty acids. In fact, Jane Foster at UT Southwestern Medical Center in Dallas recently looked at increased anxiety in people with depression and found a reduction in a community of bacteria that are linked to these short-chain fatty acids. Foster praised this latest research because it didn't look at things in isolation.
JANE FOSTER: What they've done is, using many different lenses, demonstrated low resilience and the high resilience are different from the bottom to the top.
STONE: There's lots of scientific interest in using treatments like probiotics, prebiotics, diet, even fecal transplants to influence the microbiome. But Foster says studies like this one from UCLA can be powerful because it turns up biomarkers that eventually could help steer decisions about how to use existing treatments. She says the microbiome is the product of so many different forces in our life.
FOSTER: It represents the DNA you were born with. It represents drugs you've taken over your lifespan. It represents the diet you eat today. And it represents the recent stressors that have been in your body.
STONE: And in the not-too-distant future, she believes insights about our microbiome can lead the way to better mental health. Will Stone, NPR News. Transcript provided by NPR, Copyright NPR.
NPR transcripts are created on a rush deadline by an NPR contractor. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of NPR’s programming is the audio record.