Induja Nimma, B.A.,MS – 4, University of Louisville School of Medicine
Depression is a severe global health problem. According to the Anxiety and Depression Association of America, 264 million people live with depression globally. The gut biome can influence the brain’s functions through the microbiota-gut-brain axis.1 A meta-analysis of randomized controlled trials on the effects of probiotics on depression showed a significant reduction in depression in both a healthy population and in patients with major depressive disorder (MDD).2 However, all probiotics may not be beneficial for people with mood disorders. Specific organisms have been associated with improving and worsening symptoms of depression.
In a parallel study on probiotic formulation, daily administration of Lactobacillus helveticus (R0052) and Bifidobacterium longum (R0175) significantly reduced anxiety-like behavior in rats and reduced psychological distress in healthy human volunteers.3 Additionally, Faecalibacterium, Coprococcus bacteria, and Dialister were depleted in patients with depression even after accounting for the confounding variable of antidepressant effects.4
However, Firmicutes, Actinobacteria, and Bacteroidetes seem to be associated with an increase in depressive symptoms. In a gut microbiome remodeling study, compared to healthy individuals, patients with MDD had an increase in the afore mentioned bacteria. Fecal transplant in healthy mice with this ‘depression microbiota’ taken from patients with MDD, resulted in “depression-like behaviors” that were not seen in mice transplanted with microbiota from healthy control individuals.5
Some microbiota seem to confer a positive effect while others a negative effect. This is important to consider since the probiotic supplement industry is not well regulated. If probiotics are to be implemented in the treatment regimen for depression, it is imperative to assess the efficacy and composition of commercially available products that are marketed for depression. This is something to further explore as probiotic use becomes more widely accepted as an adjunct therapy for the treatment of depression.
- Cryan JF, O’Riordan KJ, Cowan CSM, et al. The Microbiota-Gut-Brain Axis. Physiol Rev. 2019; 99(4):1877-2013. doi: 10.1152/physrev.00018.2018
2. Huang R, Wang K, Hu J. Effect of Probiotics on Depression: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Nutrients. 2016 6;8(8):483. doi: 10.3390/nu8080483
3. Messaoudi M, Lalonde R, Violle N, et al. Assessment of psychotropic-like properties of a probiotic formulation (Lactobacillus helveticus R0052 and Bifidobacterium longum R0175) in rats and human subjects. Br J Nutr. 2011;105(5):755-64. doi: 10.1017/S0007114510004319
4. Valles-Colomer M, Falony G, Darzi Y, et al. The neuroactive potential of the human gut microbiota in quality of life and depression. Nature Microbiolo 2019;4:623-632.
5. Zheng P, Zeng B, Zhou C, et al. Gut microbiome remodeling induces depressive-like behaviors through a pathway mediated by the host’s metabolism. Mol Psychiatry. 2016; 21(6):786-96. doi: 10.1038/mp.2016.44