Oregon State University reported that these types of diets are found to be related to loss of cognitive flexibility, meaning the power to adapt to changing situation. The effect was more dramatic with the high sugar diet, which was also linked to impairments in long term and short term memory.
Kathy Magnusson, a professor in the OSU College of Veterinary Medicine and principal investigator with the Linus Pauling Institute said, “It’s increasingly clear that our gut bacteria, or microbiota, 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.”
Researchers found that only after four weeks on a high fat or high sugar diet, the performance of mice on a number of mental and physical functions tests significantly declines, and the most dramatic change was in cognitive flexibility.
Magnusson said, “The impairment of cognitive flexibility in this study was pretty strong, think about driving home on a route that’s very familiar to you, something you’re used to doing. Then one day that road is closed and you suddenly have to find a new way home.”
Taking an example, a person with high levels of cognitive flexibility would be able to immediately determine the nest best route home if their usual path was blocked, while the person with poor cognitive flexibility would have a long stressful ride home.
Magnusson said, “We’ve known for a while that too much fat and sugar are not good for you.”
“This work suggests that fat and sugar are altering your healthy bacterial systems, and that’s one of the reasons those foods aren’t good for you. It’s not just the food that could be influencing your brain, but an interaction between the food and microbial changes.”
The findings of the study are published in the recent edition of the journal Neuroscience.