Published in the journal Neuroscience, the study reveals that high-fat and high-sugar diets trigger changes in gut bacteria that are largely associated with loss of “cognitive flexibility” – the ability to adapt to changing situations.

In addition, the high-sugar diet was associated with poorer short- and long-term memory.

Principal investigator Prof. Kathy Magnusson, of the College of Veterinary Medicine and the Linus Pauling Institute at Oregon State, notes there is an increasing amount of evidence emerging that gut bacteria can communicate with the brain.

“Bacteria can release compounds that act as neurotransmitters, stimulate sensory nerves or the immune system, and affect a wide range of biological functions,” Prof. Magnusson explains. “We’re not sure just what messages are being sent, but we are tracking down the pathways and the effects.”

One example of how gut bacteria may interact with the brain was revealed in a study published in the journal Cell in April, in which researchers from the California Institute of Technology (Caltech) found that gut bacteria influence the production of serotonin – a neurotransmitter responsible for maintaining mood balance.
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