A connection between the intestinal microbiota and emotions?
Does the intestinal microbiota influence our emotions? If so, how? Part of the mystery has been revealed.
To determine if a connection exists between emotions, their associated areas of the brain, and the intestinal microbiota, American researchers conducted a comparative study in 40 women in good health. First they studied the composition of their intestinal microbiota, which allowed the researchers to distinguish two major groups of women: one where the microbiota was dominated by the genus Bacteroides and the other by the genus Prevotella. Next, they conducted a neurological analysis through an MRI of the brain. Each participant was subjected to a sensory test: during these tests, each woman was shown powerful images likely to generate emotions that would be easy to measure in the MRI. They observed that the women whose microbiota was dominated by Bacteroides presented more abundant grey matter in the cerebellum, frontal regions, and hippocampus, which are the areas of the brain known for emotional, attentional, and sensory processing. On the contrary, the same regions were less strongly marked in volunteers whose microbiota was dominated by Prevotella. Although these results were obtained from a relatively small sample, they confirm that a connection exists in humans between the brain and the gut. Nevertheless, the researchers drew no conclusions on the direction of the interaction, suggesting however that the brain might be the one to influence the composition of the intestinal microbiota via the autonomous nervous system.
Tillisch K. et al. Brain structure and response to emotional stimuli as related to gut microbial profiles in healthy women. Psychosom Med. 2017 Jun 28. https://www.ncbi.nlm.nih.gov/pubmed/28661940