THE ROLE OF INTESTINAL MICROBIOTA IN DEPRESSIVE DISORDERS: A REVIEW OF CLINICAL STUDIES

Abstract

The direct link between the gut-brain axis is increasingly debated as an important factor in the development of mental illness, particularly in major depressive disorder. There is a bidirectional communication axis between brain and gut, where abnormalities in the gut microbiota affect the brain and behavior. In this sense, disturbances in the intestinal microbiota, which favor dysbiosis, are considered a risk factor for depressive disorder, and the regulation of this can be a method of therapy and prevention of depression. The present study analyzed the impact of probiotic treatment for major depressive disorder through an integrative literature review of clinical trials published in the last 5 years. In total, 8 articles were selected, in which the studied bacteria belong to the Bifidobacterium, Lactobacillus and Lactococcus genera. The articles indicate that intervention with probiotics acts in major depressive disorder through three mechanisms of action. The first refers to the production of short-chain fatty acids, reducing intestinal pH and slowing the growth of pathogenic bacteria. Promoting the synthesis of IgA which protects the intestinal barrier, preventing the passage of LPS into the circulation, decreasing systemic inflammation. Finally, by increasing the plasma levels of tryptophan and decreasing the concentration of kynurenine, consequently improving the production of serotonin. Thus, the care about the intestinal microbiota and the use of probiotics can help in the treatment of depressive disorders and also in the prevention, acting as a new therapeutic option.