A New Study Confirms That Human Emotions Are Affected By Gut Bacteria

First Posted: Jul 04, 2017 03:46 AM EDT

Gut microbiota affects people's emotional responses such as the mood and behavior. A study confirms these behavioral and neurological differences are associated with the microbial composition in healthy humans.

The findings of the study were printed in the journal Psychosomatic Medicine: Journal of Behavioral Medicine. The work was led by Dr. Kirsten Tillisch, Dr. Emeran Mayer, Arpana Gupta, Zafar Gill and Jennifer Labus of UCLA; Rémi Brazeilles, Boris Le Nevé and Muriel Derrien of Danone Research in France; Johan E.T. van Hylckama Vlieg of Microbiome and Human Health Innovation in Denmark; and Denis Guyonnet of Symrise Group in France, according to UCLA Newsroom.

The research involves 40 healthy women between the ages of 18 and 55. The researchers took and analyzed the fecal samples of the participants. They also divided the participants into two groups based on their microbial composition.

The first group had much bacterium genus referred to as Bacteroides. Meanwhile, the second group had more clusters of a genus known as Prevotella. Then, the scientists scanned the brains of the participants using the functional magnetic resonance imaging while showing them photos that could provoke positive, negative or neutral emotional responses.

The results showed that in the first group with much Bacteroides in their gut had much thickness of the gray matter in the frontal cortex and insula. These parts of the brain process complex information. They also had the bigger volume of the hippocampus that is associated with memory.

On the other hand, in the second group with much Prevotella, the participants had lower activity in the hippocampus. They also showed higher levels of distress, anxiety and irritability after looking at the images.

The scientists stated that the reduced hippocampal engagement to negative imagery may be linked to increased emotional arousal. The hippocampus aid in regulating emotions. This means that with less hippocampal volume, there could be possibly negative imagery that will arise in human emotions.

The scientists further stated that such changes have been suggested to result in less specificity of encoding the contextual details of incoming stimuli, a deficit seen in the setting of some psychiatric disorders such as post-traumatic stress disorder, depression and borderline personality disorder. They added that while the participants were healthy, it is possible that the patterns that may arise from the microbial clustering represent vulnerability factors, as Science Alert noted.

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