Gut Bacteria and How They Relate to Depression

Four key biological systems are identified as underlying the pathophysiology of major depressive disorder (MDD).

• Central dopamine, stress responses from the hypothalamic-pituitary-adrenal axis and autonomic nervous system, inflammation, and brain-derived neurotrophic factor are implicated in MDD.
• Animal studies indicate a close relationship between gut microbiota and these biological systems.
• Administration of probiotics and prebiotics may have beneficial effects on the biological markers associated with MDD.
• Bacteria that produce short-chain fatty acids, such as butyrate, and those that protect against metabolic diseases are reported to be reduced in MDD patients.
• Clinical trials of probiotics show majority beneficial effects on depression symptoms and related biological markers.

Simplified