High-fat diets have long been associated with an increased risk for medical problems, including heart disease and stroke. Researchers have now raised a possibility that diets high in fat might also increase the risk for depression and other psychiatric disorders. A study at Louisiana State University has revealed that high-fat diet alters behavior and produces signs of brain inflammation, in part, by changing the mix of bacteria in the gut, also known as the gut microbiome. These findings suggest that the gut microbiome has the eventual potential to serve as a therapeutic target for neuropsychiatric disorders.
The human microbiome consists of trillions of microorganisms, many of which reside in the gastrointestinal tract. These microbiotas are essential for normal physiological functioning of the body. However, research has suggested that alterations in the microbiome may underlie the host's susceptibility to diseases, including neuropsychiatric impairment.
During the study, non-obese adult mice were conventionally housed and maintained on a normal diet, but received a transplant of gut microbiota from donor mice that had been fed either a high-fat diet or control diet. The recipient mice were then evaluated for changes in their behavior and cognition. The mice who received the microbiota shaped by a high-fat diet showed multiple disruptions in behavior, including increased anxiety, impaired memory, and repetitive behaviors. They also showed many detrimental effects in the body, including increased intestinal permeability and markers of inflammation. Researchers suggest that signs of inflammation in their brain were also evident and may have contributed to the behavioral changes.
The study has been published in the Biological Psychiatry.
John Krystal, Editor of Biological Psychiatry, said, "This paper suggests that high-fat diets impair brain health, in part, by disrupting the symbiotic relationship between humans and the microorganisms that occupy the gastrointestinal tracks." These findings provide evidence that diet-induced changes to the gut microbiome are sufficient to alter brain function even in the absence of obesity.