Posted in Suite 101 (defunct) on February 27, 2011
Researchers have discovered that an intestinal bacterial infection causes memory problems in mice when they are exposed to acute stress. Researchers suggest that probiotics could help irritable bowel syndrome (IBS) patients who experience behavioral abnormalities. The article acknowledges that psychological stress can cause intestinal distress, and it ponders a reciprocal relationship—that intestinal infection can cause psychological distress.
The study, published in the March 2011 issue of the journal Gut, concludes that the state of intestinal health affects memory. The idea is not to completely sterilize the intestinal system, though. They found that germ-free mice lacked the ability to form memory at all. Adequate levels of good bacteria are necessary for memory function, so the idea isn’t to rid the intestines of micro-organisms, but rather to supply the gut with probiotics, otherwise known as good bacteria.
Probiotics, according to the article, are live micro-organisms that have a beneficial effect on the host; they do not damage the tissue of the host. So, probiotics make the bowel tissue healthier and stronger, while bad bacteria degrade it.
Stressed-Out Mice Prove Link Between Infection and Memory Loss
How does one stress out a mouse? Easy. Put it on a small platform surrounded by water. To measure whether the mouse is sufficiently stressed for the experiment, a light/dark box was used. Mice prefer a dark area to a bright one. So when given the choice to be in either, a mouse that is more stressed will spend more time in the darker environment.
To measure memory, infected and non-infected mice were exposed to napkin rings and cookie cutters. After being exposed to two objects, a new one was introduced. A mouse will naturally sniff the new object with greater frequency than the ones with which it’s already familiar. The researchers found that the mice that had been stressed by the water sniffed the old and new object with equal attention, suggesting that they thought all of the objects were new.
Another test included the use of a maze. Mice are naturally curious and will explore a route they perceive as new rather than one they’ve already explored. The stressed mice weren’t as good at distinguishing the new route from the old as the non-stressed mice.
The researchers, from the University of Toronto, Massachusetts Institute of Technology, and University of Calgary, found that the mice did not display behavioral abnormalities while infected or even after the infection cleared. However, when exposed to stress, they displayed memory dysfunction. When the infected mice were given daily probiotics prior to, and during, infection, memory was not impaired.
Since the mice that had no microflora in their intestines lacked the ability to form memory at all, the researchers concluded that such microflora is actually necessary and suggested that this phenomenon could translate to humans. They concluded that “probiotics could provide benefit in relation to behavioural abnormalities in patients with irritable bowel syndrome.”
Many IBS patients report difficulty with memory, often attributing it to the pain they suffer during flare-ups. This study suggests that probiotics are not only helpful in preserving memory during bouts with intestinal infection, but necessary, proven by the deficits exhibited by the mice with completely sterile systems. It also suggests that rather than remedies for memory problems, such as Omega 3 which addresses brain health, a regular diet that includes probiotics may prove to be more effective.
Source
Gareau, Melanie G., Eytan Wine, David M. Rodrigues, Joon H. Cho, and Dana J. Philpott. “Bacterial infection causes stress-induced memory dysfunction in mice.” Gut 60.31 Mar. (2011): 307-17. Print.
Disclaimer: The information contained in this article is for educational purposes only and should not be used for diagnosis or to guide treatment without the opinion of a health professional. Any reader who is concerned about his or her health should contact a doctor for advice.
