- About 4% of people in the world live with an anxiety disorder.
- Current medications used to treat anxiety do not work for everyone.
- A new study has identified a specific microbial metabolite in the gut microbiome that helps regulate brain activity linked to anxiety, via a mouse model.
- Researchers believe this finding may one day lead to new anxiety therapies targeting the gut-brain axis.
Researchers estimate that about
This type of mental health condition is typically treated with a combination of talking therapy, lifestyle changes, and medications.
However, not all people with anxiety respond well to the treatments currently available. Past studies have shown that only 60% to 85% of people treated for anxiety will respond to current treatments.
“It’s important that researchers continue to find new ways to treat anxiety because current treatments, such as benzodiazepines and SSRIs (selective serotonin reuptake inhibitors), often come with significant challenges,” H. Shawn Le, PhD, associate professor in the Signature Research Programme in Neuroscience and Behavioural Disorders at Duke-NUS Medical School in Singapore told Medical News Today.
“These drugs can take a long time to show results, and their long-term use is associated with various side effects,” he explained.
“For example, benzodiazepines can lead to dependence, sedation, cognitive impairment, and memory problems, while SSRIs are generally safer but can cause problems such as weight gain, sexual dysfunction, or gastrointestinal problems. In addition, individuals may develop an addiction to SSRIs or experience discontinuation symptoms when stopping the medication. Because of these drawbacks, it’s important to explore safer, more effective alternatives to treat anxiety that are backed by solid scientific evidence to improve patient outcomes and reduce the risk of long-term side effects.”
– H. Shawn Le, PhD
Le is the co-lead author of a new study recently published in the journal EMBO Molecular Medicine that has identified a specific microbial metabolite in the gut microbiome that helps regulate brain activity linked to anxiety, via a mouse model.
Researchers believe this finding may one day lead to new anxiety therapies targeting the gut-brain axis.
For this study, Le and his team used a model of germ-free C57BL/6 mice — mice that have had their gut microbiomes removed — to study a potential link between gut microbes and anxiety.
According to Le, the mice underwent behavioral testing to assess their emotional responses, such as anxiety. He said they were surprised to find the germ-free mice exhibited increased anxiety.
Through the study, the scientists found the extra anxiety was linked to more activity in a specific area of the brain called the basolateral amygdala.
“The basolateral amygdala is a part of the brain that helps control how we feel emotions, especially fear and anxiety,” Le explained. “It is a subregion in the
Later in the study, Le and his team tried treating the germ-free mouse model with microbial metabolites called
“Indoles are natural compounds found in plants, animals, and the human body, often derived from the amino acid tryptophan,” Le detailed. “They are also produced by tryptophan-metabolizing bacteria in the gut.”
“In our study, dietary indole supplementation was shown to reduce anxiety-related behavior in a mouse model lacking gut microbiota,” he continued. “This finding is significant because it suggests that indoles may help calm the brain’s anxiety response, offering a potential new treatment for anxiety.”
“If these findings can be replicated in other animals, companion animals, and eventually in human clinical trials with anxiety disorders, they could pave the way for novel therapies targeting the gut-brain axis,” Le added.
MNT spoke to Gary Small, MD, chair of psychiatry at Hackensack University Medical Center in New Jersey, about this study, in which he was not involved.
“In light of recent research confirming the gut-brain connection, these findings are not surprising but also quite exciting,” Small commented. “The results provide a potential mechanism for the link between gut microbes and anxiety symptoms.”
“Moreover, the amygdala is a well-documented brain region that controls anxious feelings, which makes the gut-brain pathway consistent with previous brain research in humans,” he explained. “Understanding this mechanism offers opportunities for developing novel, safe, and effective treatments for anxiety.”
“An estimated
“We have effective treatments including medications and psychotherapy, but medicines have potential side effects and talk therapies can be expensive and time-consuming. Developing a dietary intervention to mitigate anxiety would increase access to interventions, possibly reduce costs, and eliminate the risk of medication side effects,” he suggested.
MNT also spoke with Ashkan Farhadi, MD, a board-certified gastroenterologist at MemorialCare Orange Coast Medical Center in Fountain Valley, CA, and author of The Rhymes of Happiness: Weaving Science, Art and Poetry in the Pursuit of Happiness, about this research.
While doctors have been aware of the gut-brain axis for some time, Farhadi said it has now been extended into a gut-brain-microbiome axis.
“Now we know that whatever happens in the brain, changes the gut, [and] changing the gut changes the microbiome,” he detailed. “[And] vice versa — changing the microbiome changes the gut, and that changes the brain.”
Farhadi commented that it is important for researchers to continue to find new ways to treat anxiety, especially therapies that might be more natural, such as through the diet, because we should stay away from treating long-term problems with medications.
“We should have that in mind — medication is a short-term remedy for a long-term problem,” he continued. “And something like diet or altering the diet or lifestyle change that can change the microbiome in the gut is very critical.”
“At least, I can say, for cases that have a mild anxiety or mild problem with depression, that’s definitely a viable option to try something like a probiotic,” Farhadi added. “What’s the harm of it? None. What’s the benefit? It may benefit them, it may not, but definitely worth a try, or working with some diet that improves the gut health and microbiome.”
