Understanding the Connection Between the Gut–Brain Axis and Stress/Anxiety Disorders

Purpose of Review We review the association of the microbiota-gut-brain axis and anxiety disorder or stress. Recent Finding The microbiota–gut–brain axis mechanism encompasses a bidirectional relationship between the brain and gastrointestinal organs. Dysregulation of the microbiota–gut–brain axis has been actively revealed in the context of various psychiatric diseases such as neurodevelopmental disorders, schizophrenia, anxiety disorders, and depression. Summary We suggest that onset of anxiety disorders may be correlated with activation of a microbiota–gut–brain mechanism involving the immune system, neurotransmitters, and the hormonal system. By applying a microbiota–gut–brain axis mechanism, the possibility of using gastrointestinal system drugs such as probiotics and antibiotics as treatments for anxiety disorders is a possibility. Although modification of the microbiota–gut–brain axis mechanism has yet to be adopted clinically, it is expected that novel strategies employing this mechanism will be developed and deployed as new treatments not only for anxiety disorders, but also other psychiatric diseases.