Still more evidence. Note that these changes in brain volume could conceivably occur over the short term. Of course, we need ways to alter the gut biome.....
For this study, the researchers sought to identify brain and behavioral characteristics of healthy women clustered by gut microbiota profiles.
Forty women supplied fecal samples for profiling, and magnetic resonance images were taken of their brains as they viewed images of individuals, activities or things that evoked emotional responses. The women were divided by their gut bacteria composition into two groups: 33 had more of a bacterium called Bacteroides; the remaining seven had more of the Prevotella bacteria. The Bacteroides group showed greater thickness of the gray matter in the frontal cortex and insula, brain regions involved with complex processing of information. They also had larger volumes of the hippocampus, a region involved in memory processing. The Prevotella group, by contrast, showed more connections between emotional, attentional and sensory brain regions and lower brain volumes in several regions, such as the hippocampus. This group’s hippocampus was less active while the women were viewing negative images. They also rated higher levels of negative feelings such as anxiety, distress and irritability after looking at photos with negative images than did the Bacteroides group.
These results support the concept of brain-gut-microbiota interactions in healthy humans. Researchers do not yet know whether bacteria in the gut influence the development of the brain and its activity when unpleasant emotional content is encountered, or if existing differences in the brain influence the type of bacteria that reside in the gut. Both possibilities, however, could lead to important changes in how one thinks about human emotions.