This article will effect you at the gut level. I have a gut feeling that you will learn something from this article. Reading this article feels like a sock in the gut-and so on. Popular expressions are replete with references to the gut. Things felt at the “gut level” are believed to be especially true. It is as if the gut contains a sort of ancient wisdom. What the gut does contain is bacteria-lots of it. Research increasingly suggests that the interaction between this bacteria and the brain plays a larger role in mood and behavior than previously imagined.
Dr. Siri Carpenter addressed current GI research in the September issue of the APA “Monitor.” She wrote that about 100 million neurons are embedded in the lining of the gut. Even if the neural connection between the brain and gut (vagus nerve) is severed, the gut will continue to function without regulation from the brain. The gut produces neurochemicals that affect brain function in the absence of any direct neural connection. It may be true that the gut influences the brain more than the brain influences the gut.
Most of the research cited by Dr. Carpenter is, as usual, confined to rodent populations. Scientists have been able to make the same group of mice be calm, anxious, adventurous or timid by adjusting the bacteria in their gut. They have even transplanted gut bacteria from one group of mice to another; in effect transplanting the behavioral features of each group as well. The change in rodent group behavior does not necessarily require transplanting all the bacteria within the gut. The addition or subtraction of only one bacterial strain may profoundly alter rodent behavior.
The influence of the gut on the brain is only one side of the street. Many studies with monkeys and humans have demonstrated that elevated stress may suppress beneficial bacteria in the gut. Chronically stressed monkeys exhibit an overall decreased diversity of bacteria in their gut, which allows the harmful bacteria to flourish. These stressed-out monkeys are more susceptible to infection and inflammation within their gut. Once an infection has begun, the gut produces cytokines that promote inflammation. These inflammatory chemicals disrupt brain biochemistry in a way that may increase vulnerability to anxiety and depression. The “Monitor” article explained that more than half the people who suffer with GI disorders also suffer with clinically significant anxiety or depression. Many clinicians believe the prevalence of depression or anxiety in GI disorders is closer to seventy five percent.
This research may have a profound effect on the way clinicians treat both chronic GI distress and psychiatric problems. Psychology may become the treatment of choice for Irritable Bowel Syndrome. Some forms of depression and anxiety may be treated with an infusion of probiotic bacteria. While empirically validated treatments may be years away, it does present interesting options for the present. Those who suffer with chronic GI distress should consider treatment of their depressive or anxiety disorder symptoms, since a change in brain chemistry may decrease their physical suffering. Conversely, people who suffer with chronic anxiety and/or depression might consider a healthy change in their diet before making a trip to the shrink. If the options seem confusing…just listen to your gut.