The Role of the Gut–Brain Axis in Depression and Anxiety Disorders: A Systematic Literature Review

Khofifah Suci Al’Waqiah; Achmad Harun Muchsin; Kristian Liaury; Ayuni Warhamni; Uyuni Azis

Authors

Khofifah Suci Al’Waqiah Faculty of Medicine, Universitas Muslim Indonesia
Achmad Harun Muchsin Faculty of Medicine, Universitas Muslim Indonesia
Kristian Liaury Faculty of Medicine, Universitas Muslim Indonesia
Ayuni Warhamni Faculty of Medicine, Universitas Muslim Indonesia
Uyuni Azis Faculty of Medicine, Universitas Muslim Indonesia

Keywords:

Gut–Brain Axis, gut microbiota, depression, anxiety, dysbiosis, probiotics, systematic literature review

Abstract

Depression and anxiety disorders are among the most prevalent mental health conditions worldwide and have a substantial impact on individuals' quality of life. For decades, the pathogenesis of these disorders has primarily been attributed to neurotransmitter imbalances, hypothalamic–pituitary–adrenal (HPA) axis dysfunction, genetic factors, and alterations in neuroplasticity. However, emerging evidence has highlighted the significant role of the gut–brain axis in regulating brain function through bidirectional communication among the central nervous system, enteric nervous system, immune system, endocrine system, and gut microbiota. Disruption of gut microbial homeostasis (gut dysbiosis) has been associated with inflammation, altered neurotransmitter metabolism, and an increased risk of depression and anxiety. Objective of the research to analyze the role of the gut–brain axis in depression and anxiety disorders based on a systematic review of the scientific literature. This study employed a Systematic Literature Review (SLR) methodology. The findings indicate that depression and anxiety disorders are closely associated with alterations in gut microbiota composition, reduced abundance of short-chain fatty acid (SCFA)-producing bacteria, disrupted tryptophan metabolism, increased immune activation, and dysfunction of the HPA axis. The gut–brain axis operates through neuroimmunological, neuroendocrine, and metabolic pathways involving neurotransmitters, inflammatory cytokines, hormones, and microbiota-derived metabolites. Furthermore, numerous studies have demonstrated that microbiota-based interventions, including probiotics, prebiotics, synbiotics, and dietary modifications, have the potential to alleviate symptoms of depression and anxiety, although variations in dosage and intervention duration warrant further investigation. The gut–brain axis plays a crucial role in the pathogenesis of depression and anxiety disorders through complex interactions among the gut microbiota, immune system, endocrine system, and central nervous system. Microbiota-based interventions show promise as adjunctive therapeutic strategies; however, high-quality clinical studies are still needed to determine their optimal efficacy, dosage, and duration.

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