Probiotics May Alter Brain Activity Involving Emotional Regulation

Douglas K. Rex, MD

Women who took probiotics for 4 weeks had altered activity in widespread parts of the brain, including those that regulate emotional and sensory responses.

Several recent studies suggest that gut microbiota may influence brain and emotional function. Now, researchers have conducted the first intervention trial in humans to test this hypothesis.

Participants were 36 healthy women (mean age, 30) randomized to 4-week consumption of a fermented milk product containing four different probiotic bacteria species, 4-week consumption of a nonfermented milk product, or no intervention. To assess compliance, researchers analyzed stool samples to confirm the presence or absence of probiotic species in the intervention and control groups, respectively. Before and after the intervention, participants performed a validated emotional faces attention task in which they were shown faces depicting fear and anger, or control geometric forms, and asked to match them with one of two other faces (or forms). Their responses were assessed using functional magnetic resonance imaging.

In response to the emotional faces, brain activity showed widespread decrease in the probiotic group, did not change in the nonfermented milk group, and showed widespread increase in the no-intervention group. Further analysis revealed that the probiotic concoction induced alteration in the resting state activity in the periaqueductal gray matter that was correlated with the response to the emotional faces task.

Citation(s):

Tillisch K et al. Consumption of fermented milk production with probiotic modulates brain activity. Gastroenterology 2013 Jun; 144:1394