A Recent Study Shows That Probiotics Can Reduce Symptoms in Major Depressive Disorder


Although colloquialism “Trusting one’s gut” alludes to the latent knowledge that resides in our small and big intestines, for centuries, our knowledge of the relationship between the mind and the gut was more based on folklore than on solid scientific research.

That is altering. While the gut-brain axis is still mostly unknown, a study from June 2022 that was published in Translational Psychiatry offers an intriguing look at how the myriad bacteria in our guts may impact our mental health.


The Gut-Brain Axis

The findings added to the growing body of research indicating a connection between gut health and mental wellness. Else Schneider, PhD, a psychologist and senior researcher at the University of Basel in Switzerland, was one of the principal investigators of this study. The extent of the intervention's impact, according to her, was the study's most unexpected conclusion.

The fact that we discovered differences between the (research and control) groups on all levels—on the gut, the brain, and behavior—fascinated her.

She said that these results weren't temporary. The team reevaluated the gut flora and behavior four weeks after the intervention. The study itself was groundbreaking, and the results are insightful.

Inside the Study

This study is the first to investigate whether high-dose probiotic supplements given quickly can reduce depressive symptoms, alter the gut microbiome, and alter brain activity in depressed patients. In addition to their regular therapy, study participants got either a probiotic supplement or a placebo for 31 days. A probiotic was given to 21 subjects, while a placebo was given to 26 others.

The Hamilton Rating Scale for Depression, a brain scan, and a microbiota investigation of the gut were all completed by participants before and after the intervention. Four weeks following the study's conclusion, the same battery was performed without brain imaging.

The intervention group also had increased gut Lactobacillus levels and imaging-proven changes in their brain structure.

Examining the Images

Schneider considered the story's imaging section to be quite insightful. Images of scary, semi-fearful, and neutral faces were shown to participants, and scientists employed imaging to measure the functional reaction in the brain as manifested by putamen activation.

The scientists anticipated that the scary faces would undergo the biggest alterations, making the participants perceive them as less fearful. Schneider found that when participants saw frightened faces, there was no difference between the probiotic and placebo group, however, the neutral faces induced the largest change. Schneider ascribed it to the depression-related negativity bias.

According to her, healthy patients or health controls tend to view neutral faces as cheerful faces, whereas depressed patients experience them as more sad or frightening. One might be unsure which probiotic to give the patients in light of those improvements in negative bias.

Using it in Practice

The trial probiotic was Vivomixx, a popular brand found in Swiss pharmacies rather than a specialized combination. Eight distinct strains totaling 900 billion colony-forming units are present in each treatment.

  • Streptococcus thermophilus
  • Bifidobacterium breve
  • Bifidobacterium longum
  • Bifidobacterium infantis
  • Lactobacillus acidophilus
  • Lactobacillus plantarum
  • Lactobacillus paracasei
  • Lactobacillus delbrueckii subsp. Bulgaricus

Clinicians hoping to further investigate and confirm these results should choose probiotics containing the strains identified in the study because the current study failed to identify which strain caused the improvements. The research team chose a product with a variety of bacteria since, regrettably, at this time, they were unsure which particular bacteria are crucial for the reduction of depressive symptoms, according to Schneider.

Schneider added that adherence is essential for probiotic add-on therapy, just as it is for antidepressants. Failure to take probiotics for a set amount of time will prevent the microbiota from changing. Participants in the trial ingested the probiotic twice day, blended with a chilled, non-carbonated beverage.

Going Forward

While the study amply demonstrates the effectiveness of probiotics as a supplement to therapy for MDD, it also raises a number of queries that will require research in the future. For instance, why, in particular, did the probiotics cause a rebound of Lactobacillus in the gut? Which microbe, or what mixture of microorganisms, is easing symptoms? What is the way in which that improvement works, exactly?

That is the intriguing information regarding probiotics, according to Schneider. They don't cause much harm, but they're also more like a holistic approach to healing. Probiotic supplementation improves a variety of conditions.

Main Points

Though it’s still uncertain as to which probiotic strain produced the results. Further study of the probiotics on the same colonies mentioned in this article is highly suggested if clinicians want to replicate the result. Nevertheless, it is another relatively low-risk option for treating major depressive disorder (MDD) which further highlights the clinical effectiveness of the gut-brain axis.

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