Louisiana State University researchers implanted mice with gut microbes that came from mice fed on an unhealthy, high-fat diet, and found that the gut microbes alone seemed to cause neurocognitive impairments and apparent psychological problems even in the absence of obesity.

“The mice given [high-fat diet] microbiota had significant and selective disruptions in exploratory, cognitive, and stereotypical behavior compared with mice with control diet microbiota, in the absence of significant differences in body weight,” stated the researchers, publishing in Biological Psychiatry.

“The animals who received the microbiota shaped by a high-fat diet showed multiple disruptions in behavior, including increased anxiety, impaired memory, and repetitive behaviors,” stated a press release about the study. “Further, they showed many detrimental effects in the body, including increased intestinal permeability and markers of inflammation. Signs of inflammation in the brain were also evident and may have contributed to the behavioral changes.”

“This paper suggests that high-fat diets impair brain health, in part, by disrupting the symbiotic relationship between humans and the microorganisms that occupy our gastrointestinal tracks,” the editor of Biological Psychiatry said in the press release.

The press release stated that “these findings suggest that the gut microbiome has the eventual potential to serve as a therapeutic target for neuropsychiatric disorders.”

High-fat diet alters behavior and produces signs of brain inflammation (Elsevier press release on ScienceDaily, March 26, 2015)

Bruce-Keller, Annadora J., J. Michael Salbaum, Meng Luo, Eugene Blanchard, Christopher M. Taylor, David A. Welsh, and Hans-Rudolf Berthoud. “Obese-Type Gut Microbiota Induce Neurobehavioral Changes in the Absence of Obesity.” Biological Psychiatry 77, no. 7 (April 1, 2015): 607–15. doi:10.1016/j.biopsych.2014.07.012. (Abstract)