Can probiotics alter the gut microbiome to shift emotion and mood brain signatures?
The gut microbiota-brain axis plays an important role in gastrointestinal function and the regulation of mood, anxiety, and pain by communicating with the brain. Most studies have used animal models, however the following is a human double-blind study.
Researchers investigated the influence of a multi-strain oral probiotic supplement on brain function through read outs and self-reports on mood and behavior from healthy volunteers.
The study subjects included:
- Probiotic – PRP group (on the probiotic for 4 weeks),
- Placebo – PLP group (which took placebo for 4 weeks) and,
- No intervention – NI group (no intervention) with 15 participants each.
Participants brain functions were measured by functional magnetic resonance imaging (fMRI) that measured brain activation in response to decision-making and memory-based tasks, respectively. The researchers compared gut microbiome composition before and after probiotic intake and measured the implications of gut microbiota in the mechanisms triggered by probiotics.
- Probiotic administration influenced the behavioral scores for depression and anxiety questionnaires by significantly increasing positive affect and blunting vulnerability to depression in terms of hopelessness (HOP) and risk aversion (RAV).
- Probiotics improved memory performance and altered brain activation patterns.
- In the emotional recognition memory task, there was a statistically significant difference for response accuracy for unpleasant stimuli (RAU).
- For the emotional decision-making task, researchers observed that probiotic intervention was associated significant differences in the brain activation pattern between the three groups (DPRP, DPLP, DNI) in response to the neutral>baseline contrast (N>B) and unpleasant>baseline contrast (U>B).
- Self-reported behavioral measures correlated with Blood Oxygenation Level Dependent (BOLD) signal change in the probiotic group.
- Probiotics administration was associated with subtle, but significant changes in gut microbial community composition.
- Microbial community composition mirrored behavioral performance in questionnaires and fMRI recognition memory task.
Conclusion/ “This study provides multidimensional evidence that administration of a multi-strain probiotic and the associated change in gut microbiota composition has a significant interrelated impact on behavioral scores and functional MRI measures in distinct brain areas involved in emotional decision-making and emotional memory processes. The influence of probiotics on human brain metabolism remains an important question for future investigations. A deeper understanding of the underlying mechanisms will help to refine the clinical use of probiotic supplements in the future. The results of the current study are relevant in guiding future clinical.”