Microbiome modulation as a novel therapeutic modality for anxiety disorders: A review of clinical trials

Abstract

Anxiety disorders are one of the major conditions in psychiatry characterized by symptoms such as worry, social and performance fears, unexpected and/or triggered panic attacks, anticipatory anxiety, and avoidance behaviors. Recent developments have drawn attention to the putative involvement of peripheral systems in the control of anxiety, and the gut microbiota has come to light as an emerging peripheral target for anxiety. The relationship between the gut-brain axis, a bidirectional communication network between the central nervous system (CNS) and enteric nervous system (ENS), and anxiety has been the subject of some recent studies. Therefore, this systematic review analyzed clinical trials evaluating the potential of microbiome modulation methods in mitigating and ameliorating anxiety disorders. Clinical studies on probiotic, prebiotic, synbiotic supplements, dietary interventions, and fecal microbiota transplantation in anxiety disorders were screened. All of the studies examined the effects of probiotic intervention. One of these studies compared a prebiotic-rich diet with probiotic supplementation. Longitudinal analyses showed that the probiotic intervention alleviated anxiety. However, most of the controlled studies reported that the probiotic intervention did not make a difference compared to placebo. Thus, the current findings suggest that it is too early to consider the promising role of microbiome modulation in the treatment of anxiety disorders. However, it is obvious that more clinical research is needed to clarify issues such as probiotic strains, prebiotic types, and their doses that may be effective on anxiety disorders.