Researchers studying Irritable Bowel Syndrome say that they may have found a connection between gut bacteria and behavioral symptoms of IBS, and also suggest a potential connection between gut bacteria and “the spectrum of brain disorders ranging from mood or anxiety to other problems that may include autism, Parkinson’s disease, and multiple sclerosis.” IBS is a gastrointestinal disorder that affects more than one-tenth of the global population.
IBS symptoms include severe gut pain, bloating, constipation, or diarrhea. Symptoms can also include depression or anxiety, according to Medical News Today, which reported that a biomarker for Irritable Bowel Syndrome hasn’t been identified, so it is diagnosed clinically. Some current treatments for IBS include eliminating FODMAPS (carbohydrates that can cause fermentation in the bowels) and medications such as laxatives and antispasmodics. It is not known what causes Irritable Bowel Syndrome.
Researchers from the Farncombe Family Digestive Health Research Institute at McMaster University and researchers from the University of Waterloo say that they may have found a link between gut bacteria and the behavioral symptoms found in people suffering from IBS. The new findings were published in the journal Science Translational Medicine. The research team was reportedly led by Dr. Premysl Bercik and Dr. Stephen Collins. The team was trying to see if fecal bacteria from humans with IBS could cause mice to exhibit similar gut and brain symptoms as a human with IBS.
They used fecal transplants to test the theory. Using germ-free mice, the researchers transplanted bacteria from two groups of patients with IBS and another group that did not have IBS. Of the two IBS groups, one group had anxiety and the other group did not. Sure enough, after the transplant, the mice developed the same behavioral symptoms and gut dysfunction as their transplant donors had, including behavior that indicated the mice were suffering from anxiety.
“This is a landmark study because it moves the field beyond a simple association, and towards evidence that changes in the microbiota impact both intestinal and behavioral responses in IBS,” Giada De Palma, the study’s first author, explained.
“The intestinal microbiota may play some role in the spectrum of brain disorders ranging from mood or anxiety to other problems that may include autism, Parkinson’s disease, and multiple sclerosis,” the authors further explained.
The abstract summarized the findings.
“To evaluate a functional role for commensal gut bacteria in IBS, we colonized germ-free mice with the fecal microbiota from healthy control individuals or IBS patients with diarrhea (IBS-D), with or without anxiety, and monitored gut function and behavior in the transplanted mice. Microbiota profiles in recipient mice clustered according to the microbiota profiles of the human donors. Mice receiving the IBS-D fecal microbiota showed a taxonomically similar microbial composition to that of mice receiving the healthy control fecal microbiota. However, IBS-D mice showed different serum metabolomic profiles. Mice receiving the IBS-D fecal microbiota, but not the healthy control fecal microbiota, exhibited faster gastrointestinal transit, intestinal barrier dysfunction, innate immune activation, and anxiety-like behavior.”
This research joins a growing body of evidence that supports a connection between a spectrum of brain disorders and gut bacteria. Another paper from McMaster University from earlier suggested that PTSD might be prevented with gut bacteria, Medical News Today reported.
“A team working in the field of warfighter performance suggests gut microbes may hold the key to curing or preventing post-traumatic stress disorder and mood disorders, such as anxiety and depression.”
Interestingly, stressed mice reportedly became markedly calmer when fed live bacteria from fecal material that was collected from calm mice. This research was part of a project sponsored by the Warfighter Performance Department in the Office of Naval Research..
“This is extremely important work for United States warfighters because it suggests that gut microbes play a strong role in the body’s response to stressful situations, as well as in who might be susceptible to conditions like PTSD,” ONR Program Officer Dr. Linda Chrisey said when the earlier research was announced. The team used magnetic resonance spectroscopy (MRS) to look at changes in brain chemistry. The brain scans showed that the bacterial transplants aimed at calming the mice were successful and there were notable chemical differences between their brains while stressed and after the probiotic treatment. The next steps include further experiments using fecal transplants as well as clinical trials in humans.
The researchers are now planning further experiments with fecal transplants from calm mice to stressed mice, and they also hope to get funding to carry out clinical trials in humans. Reportedly, this area of research is considered top priority research given its impact on military performance.
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