Well, not totally. Irritable bowel syndrome (IBS) is also in your gut, of course. But recent research has revealed structural changes in the brains of people diagnosed with IBS that demonstrate an organic component to the disorder. This is huge, as it's the first time scientists have confirmed an association between the gut microbiota and the brain regions involved in processing the body's sensory information.
Emeran Mayer, a world-renowned gastroenterologist and neuroscientist, and the codirector of CURE: Digestive Diseases Research Center at UCLA, has been studying for years how the gut's microorganisms and our nervous system influence health and disease. A recent study published in the journal Microbiome suggests that signals generated by the brain can affect the composition of the microbes present in the intestine and that the chemicals in the gut can alter the structure of the human brain.
Most of the early research on the relationship between gut microflora and the brain's functioning has been performed on mice, but this recent study combined clinical tests on adults diagnosed with IBS and healthy adults as controls and determined that the subjects with IBS could be clustered into two groups based on differences in their gut microbes. One group's microbiota couldn't be distinguished from the healthy control subjects, while the composition of the other group's gut bacteria was distinctly different.
One of the most interesting outcomes of the research was the discovery of subtle but significant differences in brain structure between the subgroups. The study found that areas of the brain associated with unifying the body's sensory information were slightly larger in the subgroup whose microbiota differed more from those of healthy subjects. In addition, the front part of the insular cortex (the area of the brain that's linked with keeping certain body functions in balance, as well as processing emotions and managing cognitive functions) was slightly smaller in this group, as was their ventral prefrontal cortex, the area of the brain involved with personality development.
Note that these subgroups are not correlated with clinical findings related to bowel habits or psychological symptom scores. In fact, the findings suggest a possible new classification of IBS based on patients' microbial profiles rather than on clinical observations. Additionally, the findings may help explain why treatments that alter the composition of gut microbes (such as antibiotics, prebiotics, and probiotics), fiber supplementation, and certain dietary approaches may only be effective with particular subgroups of patients and may worsen symptoms in other subgroups.
Another interesting discovery was that the subjects in the IBS group with the altered gut microbiota had a greater history of early life trauma and a longer duration of IBS symptoms. Surprisingly, trauma early in life has been linked with structural and functional brain changes, and it's also been associated with alterations to the gut's microbial composition. The researchers theorize that a history of early adverse life events may result in lifelong changes to a person's gut microbiota, and that these alterations may send signals to the brain, which in turn affect the brain's sensitivity to gut stimuli, one of the telltale characteristics of IBS.
The ties between gut microbes and the brain are complex. Other conditions, such as anxiety, chronic fatigue syndrome, and Parkinson's disease, also show intricate interactions with the microbiome. In the future, it's likely that identifying IBS subgroups based on a patient's gut microbiota, metabolomic profile, and corresponding brain signature will play an important role in routine IBS screening and in optimized targeted therapies, such as cognitive behavior therapy, mindfulness-based stress reduction, and specific drugs.
QUESTIONS FOR DISCUSSION:
Do you have a history of childhood trauma or early adverse life events? Do you think that your level of emotional sensitivity is more heightened than people who don't have IBS? Do you struggle with your ability to process your emotions? Do the findings of this study resonate with you on a personal level? Let's get a dialogue going!
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