The study, which observed the impact of a high-fat and -sugar diet on mice, found that the diet impacted gut bacteria — which helps the body digest certain foods, stave off infection, and even fight obesity by influencing metabolism
The diet’s influence on gut bacteria, in turn, was found to have a negative impact on the mice’s cognitive abilities, suggesting gut bacteria has yet another method of influencing overall health — by communicating directly 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,” said Kathy Magnusson, the paper’s lead researcher and a professor at Oregon State University.
After a month of the high-fat and high-sugar diet, the mice in the experimental group experienced noticeable declines in cognitive flexibility and in their ability to perform in water-maze tests, in which the mice were tested for short- and long-term memory.
“Think about driving home on a route that’s very familiar to you, something you’re used to doing,” suggests Magnusson. “Then one day, that road is closed and you suddenly have to find a new way home.”
For those mice with less healthy diets, their ability to adapt to challenges in the water maze was “significantly impaired” when compared to the control group of mice who received a normal diet.