The saNeuroGut Initiative: Investigating the Gut Microbiome and Symptoms of Anxiety, Depression, and Posttraumatic Stress

Neuroimmunomodulation. 2025;32(1):1-15. doi: 10.1159/000542696. Epub 2024 Nov 19.

Abstract

Introduction: Common mental disorders, such as anxiety disorders, depression, and posttraumatic stress disorder (PTSD), present a substantial health and economic burden. The gut microbiome has been associated with these psychiatric disorders via the microbiome-gut-brain axis. However, previous studies have focused on the associations between the gut microbiome and common mental disorders in European, North American, and Asian populations. As part of the saNeuroGut Initiative, we assessed associations between gut microbial composition and self-reported symptoms of anxiety, depression, and posttraumatic stress (PTS) among South African adults.

Methods: Participants completed validated, online self-report questionnaires to evaluate symptoms of state anxiety, trait anxiety, depression, and PTSD. Eighty-six stool-derived microbial DNA samples underwent sequencing of the V4 region of the 16S rRNA gene to characterise gut bacterial taxa in the sample.

Results: No significant associations were observed between symptom severity scores and alpha (Shannon and Simpson indices) and beta (Aitchison distances) diversity metrics. Linear regression models revealed that the abundances of Catenibacterium, Collinsella, and Holdemanella were significantly positively associated with the severity of PTS symptoms.

Conclusion: Catenibacterium, Collinsella, and Holdemanella have each previously been associated with various psychiatric disorders, with Catenibacterium having been positively associated with symptoms of PTSD in another South African cohort. This study sheds light on the relationship between the human gut microbiome and symptoms of anxiety, depression, and PTS in a South African adult sample.

Keywords: Gut microbiota; Gut-brain interaction; Mental health; Microbiome-gut-brain axis; Psychiatry.

MeSH terms

  • Adult
  • Anxiety* / microbiology
  • Anxiety* / psychology
  • Depression* / epidemiology
  • Depression* / microbiology
  • Depression* / psychology
  • Female
  • Gastrointestinal Microbiome* / genetics
  • Gastrointestinal Microbiome* / physiology
  • Humans
  • Male
  • Middle Aged
  • South Africa / epidemiology
  • Stress Disorders, Post-Traumatic* / epidemiology
  • Stress Disorders, Post-Traumatic* / microbiology
  • Stress Disorders, Post-Traumatic* / psychology
  • Young Adult

Grants and funding

Research reported in this publication was supported by the South African Medical Research Council (SAMRC) for the “Shared Roots” Flagship Project (Grant No. MRC‐RFA‐IFSP01‐2013/SHARED ROOTS). This work was supported by the South African Medical Research Council (SAMRC)/Stellenbosch University Genomics of Brain Disorders (GBD) Extramural Research Unit, the SA Society for Biology Psychiatry (NPC 2021/925075/08), and the Harry Crossley Foundation Research Grant. MO was supported by the Stellenbosch University Postgraduate Scholarship Programme and the Prof HW Truter bursary. PS was supported by the Stellenbosch University Subcommittee C Grant, the National Research Foundation of South Africa, and the SAMRC/Stellenbosch University GBD Unit. SMM is supported by an Una4Career grant (European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No 847635), a Knowledge Generation Grant from the Ministry of Science and Innovation (Spain) (PID2021-126468OA-I00). The work by Leigh van den Heuvel was supported in part by the National Research Foundation of South Africa (Grant No. 138430) and by the SAMRC under a Self-Initiated Research Grant. The content hereof is the sole responsibility of the authors and does not necessarily represent the official views of the SAMRC or the funders. The funders had no role in the design, data collection, data analysis, and reporting of this study.