ASSOCIATION BETWEEN INTESTINAL DYSBIOSIS AND MAJOR DEPRESSIVE DISORDER: A SYSTEMATIC REVIEW

Abstract

Introduction: Major Depressive Disorder (MDD) affects around 300 million people globally, being one of the main causes of work incapacity and associated with high suicide rates. Conventional approaches, such as pharmacological therapy and psychotherapy, fail in up to a third of cases, leading to a search for new therapeutic interventions. In this context, the imbalance in the gut microbiota, known as dysbiosis, affects mood, behavior and cognition, making therapeutic strategies such as probiotics, prebiotics and fecal microbiota transplantation promising for mitigating or resolving depressive symptoms, including preventively. Objective: To verify the evidence on the improvement of MDD symptoms through the treatment of intestinal dysbiosis, to describe the physiological changes triggered by dysbiosis and to identify the neurochemical processes that associate these changes with psychological health. Methodology: This is a systematic review without meta-analysis, using the following PICO strategy: P - Individuals diagnosed with major depressive disorder; I - Modulation of the intestinal microbiome with probiotics or prebiotics; C - Patients who did not use probiotics and/or probiotics; O - Decreased scores on validated depression scales. Articles will be searched on the PUBMED, MEDLINE and LILACS platforms in Portuguese, Spanish and English, in the last 10 years, using the search strategy ("Major depressive disorder" AND "Dysbiosis") OR ("Major depressive disorder" AND "Probiotics") OR ("Major depressive disorder" AND "Prebiotics"). Results and Discussion: The search yielded 280 studies, of which 276 were excluded. In the end, 4 studies were included in the analysis. The results suggest that modulation of the gut microbiome may have a beneficial effect on reducing MDD symptoms, especially in longer interventions and with specific populations. However, the heterogeneity of the studies and the variability of the results indicate that the response to treatment is not uniform, pointing to the need for more personalized interventions. The changes observed in inflammatory and metabolic biomarkers also indicate that treatment of dysbiosis may act on neurochemical pathways that influence mood and cognition, but these effects need to be better understood. Conclusion: Modulation of the gut microbiome shows promise as an adjunctive intervention in the treatment of MDD, particularly through probiotics and prebiotics. However, due to the variability in the results of the studies, more research is needed to better define the clinical efficacy of this approach and to understand the underlying mechanisms that link gut health to mental health. Personalizing interventions and investigating specific subgroups that may benefit most from these therapies are promising areas for future research.