The Gut Connection: A Narrative Review on the In-depth Analysis of Gut Microbiota and Metabolites in Depression

Depression is a prevalent mood disorder with significant public health implications. Despite extensive research, its precise causes remain inadequately understood. Recently, interest has surged in the role of the gut microbiome and its metabolites in the pathophysiology of depression. This review aims to provide a comprehensive overview of the relationship between gut microbiota, its metabolites, and depression while exploring potential mechanisms influencing the efficacy of antidepressant medications. A narrative review methodology was employed, synthesizing recent studies utilizing a multi-omics approach. We examined alterations in gut microbiome composition and metabolite production in individuals diagnosed with depression, discussing the technical tools and methods commonly applied in this research area. The findings indicate that individuals with depression show significant alterations in gut microbiome composition, notably an imbalance in Firmicutes, Bacteroidetes, and Actinobacteria. Changes in metabolite production, including short-chain fatty acids, tryptophan, and bile acids, were also observed. Moreover, the review highlights that antidepressant medications may exert their therapeutic effects by modulating gut microbiota and its metabolites. This review emphasizes the intricate interplay between gut microbiota, its metabolites, and depression, revealing critical insights into the mechanisms underlying antidepressant efficacy. We recommend that future research focus on elucidating these interactions to develop innovative therapeutic strategies, potentially transforming the management of depression through microbiota-targeted approaches.