Healthy Gut Microbes Equals a Healthy Brain
The Relationship between Intestinal Microbiota Imbalance, Stress, and Memory
High levels of psychological stress have been shown to result in intestinal problems such as chronic inflammation and food allergies, caused by dysregulation of the microbiota in the gut. This is as true in humans as it is in mice and rats used in research. But until recently the question had never been asked if problems in the gut influence the function of the brain.
A November 2010 study, published online by the journal “Gut”, showed that mice with bacterial colitis exposed to acute stress develop problems with learning and memory. The colitis caused by infecting the mice with an intestinal bacterium resulted in an imbalance of the gut microbiota. This on its own was not enough to cause problems with memory but as soon as the mice were exposed to acute stress they developed difficulty in identifying novel objects and exploring new environments. These deficits remained up to 30 days after infection. Treatment with probiotics prevented the deficits in memory from developing indicating that the problems were not just a function of stress but also of the microbiota imbalance. Interestingly, ‘germ-free’ mice which did not have any gut microbiota at all displayed memory deficits without the presence of colitis or acute stress suggesting that the presence of functional gut microbiota is essential to proper brain function. The link between the gut and the brain was proposed to be brain-derived neurotrophic factor (BDNF), levels of which were significantly reduced in the mice that showed memory deficits.
Although this was a study in mice is it quite possible that a similar phenomenon occurs in humans and indicates that the use of probiotics could prevent behavioral abnormalities from developing in patients with irritable bowel syndrome.
Author: Ruth Warre is scientific writer and editor based in Toronto. Her writing has covered many biomedical topics from Parkinson’s disease to aging. She has a PhD in Neuroscience and her research work has been published in several scientific journals.
