Stress matters: Randomized controlled trial on the effect of probiotics on neurocognition.
Neurobiology of stress. 2019;10:100141
Plain language summary
Increasing animal studies indicate the role of probiotics in regulating mood and cognition through the gut-brain axis, however in human studies evidence of this causal association is lacking. The aim of this double-blind, randomised, placebo-controlled intervention was to investigate the effects of probiotics on neurocognitive measures in 58 healthy participants. Participants were randomly assigned to either probiotic or placebo group and were tested once before and after the 28-day intervention. The neurocognitive outcomes measured included emotion reactivity, emotion regulation, cognitive control and the effects of acute stress on working memory. These were assessed through functional MRI (fMRI) and questionnaires. This study found when stress was induced, probiotic supplementation led to a significant improvement in working memory performance. Without stress, there was no causal association between neurocognitive outcomes and probiotic intake. Based on these results, the authors conclude that during challenging situations, probiotics can aid in buffering the detrimental effects of stress on cognition.
undefined: Probiotics are microorganisms that provide health benefits when consumed. In animals, probiotics reverse gut microbiome-related alterations in depression-like symptoms, in cognition, and in hormonal stress response. However, in humans, a causal understanding of the gut-brain link in emotion and cognition is lacking. Additionally, whether the effects of probiotics on neurocognition are visible only in presence of stress, remains unclear. We investigated the effects of a multispecies probiotic (Ecologic Barrier) on specific neurocognitive measures of emotion reactivity, emotion regulation, and cognitive control using fMRI. Critically, we also tested whether probiotics can buffer against the detrimental effects of acute stress on working memory. In a double blind, randomized, placebo-controlled, between-subjects intervention study, 58 healthy participants were tested once before and once after a 28-day intervention. Without stress induction, probiotics did not affect brain, behavioral, or related self-report measures. However, relative to placebo, the probiotics group did show a significant stress-related increase in working memory performance after supplementation. This change was associated with intervention-related neural changes in frontal cortex during cognitive control exclusively in the probiotics group. Overall, our results show neurocognitive effects of a multispecies probiotic in healthy women only under challenging situations, buffering against the detrimental effects of stress on cognition.