Gut Microbiota Dysbiosis in Depression: Pathological Correlations, Molecular Pathways, and Therapeutic Interventions

Major depressive disorder (MDD) ranks as a primary contributor to global ill health and disability, with treatments often proving insufficient. Recent study has increasingly found a strong correlation between gut microbiome diversity and mood-related behaviors, including MDD. Depression can alter gut microbiota (GM) composition, while intentional modulation of the GM may conversely influence depressive symptoms. This phenomenon arises from dynamic bidirectional interactions between the gut and brain, although the exact pathways are not yet fully elucidated. Proposed pathways include, but are not limited to, neural circuits, the endocrine system, immune responses, and metabolic regulation. Clinical data have also shown that regulating the GM through probiotics and prebiotics has the potential to alleviate depressive symptoms. This review summarizes contemporary research on the composition and modulatory functions of GM in MDD, and explores the predictive potential of GM for depression as well as the therapeutic prospects of probiotics, aiming to provide insights and directions for future research.