The Power of Psychobiotics in Depression: A Modern Approach through the Microbiota-Gut-Brain Axis: A Literature Review

Abstract

The microbiota-gut-brain (MGB) axis is a complex communication network linking the gut, microbiota, and brain, influencing various aspects of health and disease. Dysbiosis, a disturbance in the gut microbiome equilibrium, can significantly impact the MGB axis, leading to alterations in microbial composition and function. Emerging evidence highlights the connection between microbiota alterations and neurological and psychiatric disorders, including depression. This review explores the potential of psychobiotics in managing depressive disorders, emphasizing their role in restoring microbial balance and influencing the MGB axis. Psychobiotics exhibit positive effects on the intestinal barrier, immune response, cortisol levels, and the hypothalamic-pituitary-adrenal (HPA) axis. Studies suggest that probiotics may serve as an adjunct therapy for depression, especially in treatment-resistant cases. This review discusses key findings from studies on psychobiotics interventions, emphasizing their impact on the gut-brain axis and mental health. The increasing acceptance of the expanded concept of the MGB axis underscores the importance of microorganisms in mental well-being. As our understanding of the microbiome's role in health and disease grows, probiotics emerge as promising agents for addressing mental health issues, providing new avenues for therapeutic interventions in depressive disorders.

Keywords: depression; gut–brain axis; microbiota–gut–brain axis; probiotics; psychobiotics.

Figure 1

Bidirectional communication between gut microbiota and gut-brain axis (GBA). Microbiota communicates with the GBA through different mechanisms viz. direct interaction with enterocytes (enteric message), via immune cells (immune message), and via contact to neural (vagus nerve) endings (neuronal message) to influence the central nervous system (CNS). During dysbiosis a synthesis of several microbial products viz. metabolites, neurotransmitters, and cytokines gain access to the brain via the bloodstream.

Figure 2

Overview of the pathways of antidepressant effects on the GBA axis exerted by probiotics and prebiotics. 5-HT—5-hydroxytryptamine; DA—dopamine; GABA—γ-aminobutyric acid; BDNF—brain-derived neurotrophic factor; BBB—blood–brain barrier; EPI—epinephrine; NE—norepinephrine; HPA axis—hypothalamic-pituitary-adrenal axis; IL—interleukin; TNF-α—tumour necrosis factor α; CRP—C-reactive protein; TGF-β—transforming growth factor β; IgA—immunoglobulin A; TJs—tight junctions; SCFAs—short-chain fatty acids; LPS—lipopolysaccharide.