A recent study published in the journal Neuroscience at Oregon State University indicates that both a high-fat and a high-sugar diet causes changes in gut bacteria that appear related to a significant loss of ‘cognitive flexibility’.

Researchers found that the effect was found to be more serious on the high-sugar diet, which also showed an impairment of early learning for both long-term and short-term memory.

The findings of the study are consistent with the earlier studies about the impact of fat and sugar on cognitive function and behavior. It suggests that some of these issues might be linked to alteration of the microbiome, a complex mixture in the digestive system of about 100 trillion microorganisms.

Kathy Magnusson, a professor in the OSU College of Veterinary Medicine and principal investigator with the Linus Pauling Institute, said in a statement that it is quite clear that gut bacteria can communicate with the human brain.

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

The research was conducted on laboratory mice that consumed different diets and then faced a variety of tests, such as water maze testing, to monitor changes in their mental and physical function, and associated impacts on various types of bacteria.

Magnusson said so far mice have proven to be particularly good model for studies relevant to humans, on topics such as aging, spatial memory, obesity and other issues.