Can Stomach Bacteria Make You Dumber?

Scientists have uncovered a connection between certain ulcer-causing bacteria and cognitive impairment. Tori Rodriguez from Scientific American MIND explains the latest research.

QDT Editor
December 4, 2013

One type of harmful bacteria escaping the gut might be Helicobacter pylori, the main cause of stomach ulcers. H. pylori may contribute to cognitive impairment or Alzheimer's disease, according to a study published in the June 2013 issue of Psychosomatic Medicine. Compared with uninfected individuals. people who tested positive for H. pylori performed worse on cognitive tests, including ones assessing verbal memory.

Some labora­tory evidence indicates that H. pylori cells can escape the gut and sneak into the brain. There the cells aggregate with the amyloid proteins characteristic of Alzheimer's and instigate the buildup of plaque, suggests study co-author May Baydoun, a staff scientist at the Nation­al Institute on Aging. The National Institutes of Health estimates that about 20% of people younger than 40 and half of adults older than 60 are infected with the bacteria, which can be treated with antibiotics.      

Bugs That Influence the Brain

Preliminary research suggests that these common gut microbes can also affect our thoughts and feelings:

  • Helicobacter pylori:  Children infected with this ulcer-causing bacterium performed worse on IQ tests, suggesting a possible link between H. pylori infection and cognitive development.
  • Lactobacillus helveticus and Bifidobacterium longum: Healthy human volunteers who consumed a probiotic mix of these bacteria exhibited Jess anxiety and depression.
  • Probiotic bacteria: Healthy women who consumed yogurt containing these bugs showed less activity in brain regions that process emotions and physical sensations. Researchers do not yet know whether these effects were beneficial; they also have not discovered the mechanism underlying the observed shift in brain activity.
  • Lactobacilli: Healthy students had fewer of these bacteria present in their stool during a high-stress exam time compared with a less stressful period during the semester. The findings suggest a potential link between stress and gut microbes, but the exact relation remains unknown.

See also: What is Gut Microbiota? and How to Get the Most from Your Probiotic Supplements


Reproduced with permission.  Copyright ©2013 Scientific American, a division of Nature America, Inc.  All rights reserved.  By Tori Rodriguez, Scientific American MIND.

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