The effects of multispecies probiotics on sad mood reactivity

Background

Recent insights have led to the hypothesis that probiotic supplementation may act as an adjuvant strategy to ameliorate or prevent depression and therefore may be used therapeutically to modify stress responses and symptoms of anxiety and depression. A reduction in anxious and depressive behavior after feeding probiotics has been seen in mice and rats. Less research is done with humans, but there are certainly promissing results with the same probiotica used in the previous mentioned studies with rats and mice. Not all combinations of probiotics seem succesful, therefore more research is needed.

Objective

Heightened cognitive reactivity to normal, transient changes in sad mood is an established marker of vulnerability to depression and is considered an important target for interventions. The present study aimed to test if a multispecies probiotic may reduce cognitive reactivity in non-depressed individuals.

Design

In a triple-blind, placebo-controlled, randomized, pre- and post-intervention assessment design, 20 young and healthy participants without current mood disorder received a 4-week probiotic food-supplement intervention with the multispecies probiotics, while 20 control participants received a placebo for the same period. In the pre- and post-intervention assessment, cognitive reactivity to sad mood was assessed using the revised Leiden index of depression sensitivity scale (self-report). All participants believed they were supplied with probiotic supplementation.

Results

The two groups of participants (placebo and probiotics) were comparable in terms of depression and anxiety scores at baseline and follow-up. Importantly, participants did not show any sign of depression and anxiety in either sessions. Compared to participants who received the placebo intervention, participants who received the 4-week multispecies probiotics intervention showed a significantly reduced overall cognitive reactivity to sad mood, which was largely accounted for by reduced rumination and aggressive thoughts.

Limitations

1. Dietary measures were not included, neither was the diet during the research period.

2. It was not verified that the probiotics were consequently taken.

3. Most of the participants were female.

Conclusion

The probiotic intervention reduced aggressive and ruminative thoughts in response to sad mood. Probiotics supplementation warrants further research as a potential preventive strategy for depression.