Although many people are aware of the communication that occurs between the gastrointestinal (GI) tract and the central nervous system, fewer know about the ability of the central nervous system to influence the microbiota or of the microbiota’s influence on the brain and behavior. Within the GI tract, the microbiota have a mutually beneficial relationship with their host that maintains normal mucosal immune function, epithelial barrier integrity, motility, and nutrient absorption. Disruption of this relationship alters GI function and disease susceptibility. Animal studies suggest that perturbations of behavior, such as stress, can change the composition of the microbiota; these changes are associated with increased vulnerability to inflammatory stimuli in the GI tract. The mechanisms that underlie these alterations are likely to involve stress-induced changes in GI physiology that alter the habitat of enteric bacteria. Furthermore, experimental perturbation of the microbiota can alter behavior, and the behavior of germ-free mice differs from that of colonized mice. Gaining a better understanding of the relationship between behavior and the microbiota could provide insight into the pathogenesis of functional and inflammatory bowel disorders.
Chronic fatigue syndrome (CFS) is complex illness of unknown etiology. Among the broad range
of symptoms, many patients report disturbances in the emotional realm, the most frequent of
which is anxiety. Research shows that patients with CFS and other so-called functional somatic
disorders have alterations in the intestinal microbial flora. Emerging studies have suggested that
pathogenic and non-pathogenic gut bacteria might influence mood-related symptoms and even
behavior in animals and humans. In this pilot study, 39 CFS patients were randomized to receive
either 24 billion colony forming units of Lactobacillus casei strain Shirota (LcS) or a placebo daily for
two months. Patients provided stool samples and completed the Beck Depression and Beck
Anxiety Inventories before and after the intervention. We found a significant rise in both
Lactobacillus and Bifidobacteria in those taking the LcS, and there was also a significant decrease in
anxiety symptoms among those taking the probiotic vs controls (p = 0.01). These results lend
further support to the presence of a gut-brain interface, one that may be mediated by microbes
that reside or pass through the intestinal tract.
Really? If true, then that is fascinating… Can you link to any of the recent research, though?
EDIT: by popular demand. I’ll be moving this to a discussion instead.
EDIT: the discussion thread is here
As in the attribution, I’m quoting from: Hejitz et.al.: Normal gut microbiota modulates brain development and behavior, 2011.
Here is a review paper.
See also the current special section of science magazine, or google scholar.
Here’s the abstract from The Relationship Between Intestinal Microbiota and the Central Nervous System in Normal Gastrointestinal Function and Disease00346-1/abstract):
Here are results from an RCT on humans with chronic fatigue syndrome