Effect of Fecal Microbiota Transplant on Symptoms of Psychiatric Disorders: A Systematic Review

Abstract

Background: The Gut-Brain-Axis is a bidirectional signaling pathway between the gastrointestinal (GI) tract and the brain. The hundreds of trillions of microorganisms populating the gastrointestinal tract are thought to modulate this connection, and have far reaching effects on the immune system, central and autonomic nervous systems, and GI functioning. These interactions have also been linked to various psychiatric illnesses such as depression, anxiety, substance abuse, and eating disorders. It is hypothesized that techniques aimed at strengthening and repopulating the gut microbiome, such as Fecal Microbiota Transplant (FMT), may be useful in the prevention and treatment of psychiatric illnesses. Methods: A systematic search of five databases was conducted using key terms related to FMT and psychiatric illnesses. All results were then evaluated based on specific eligibility criteria. Results: Twenty-one studies met the eligibility criteria and were analysed for reported changes in mood and behavioural measures indicative of psychiatric wellbeing. The studies included were either entirely clinical (n=7), preclinical with human donors (n=7), or entirely preclinical (n=7). All studies found a decrease in depressive and anxiety-like symptoms and behaviours resulting from the transplantation of healthy microbiota. The inverse was also found, with the transmission of depressive and anxiety-like symptoms and behaviours resulting from the transplantation of microbiota from psychiatrically ill donors to healthy recipients. Conclusion: There appears to be strong evidence for the treatment and transmission of psychiatric illnesses through FMT. Further research with larger sample sizes and stronger scientific design is warranted in order to fully determine the efficacy and safety of this potential treatment.

Gut microbes in neurocognitive and mental health disorders

“…The use of FMT alleviated Alzheimer's pathology in the brain of mice and helps to improve cognitive deficits and reduce amyloid-b [162]. A systematic review highlighted that patients receiving faecal transplant from healthy donors were found to have a decrease in depressive and anxiety-like symptoms [163]. Both the use of probiotics and FMT showed some promise in the treatment of mental health and neurocognitive disorders.…”

The Safety, Efficacy, and Tolerability of Microbial Ecosystem Therapeutic-2 in People With Major Depressive Disorder and/or Generalized Anxiety Disorder: A Phase 1, Open-Label Study

“…Pre-clinical research has found both the conferment of psychiatric symptoms through the transplantation of fecal microbiota from animals displaying behaviours related to psychiatric illnesses to antibiotic-treated animals (24-27),as well as the amelioration of psychiatric symptoms after FMT from healthy animals to those displaying psychiatric symptoms (28,29). Clinical research has found the transplantation of microbiota from a healthy donor to an ill recipient often results in the alleviation of psychiatric symptoms (11). As MET-2 is a collection of bacteria cultured from the gut of a healthy human donor, it was suspected, and subsequently supported by this study, that treatment with MET-2 would result in symptom improvement similar to that seen in clinical FMT studies.…”

“…As such, the "gut-brain axis" (GBA) which consists of bidirectional signaling between the gastrointestinal (GI) tract and the brain (10), has become a novel target for treatment of mood and anxiety symptoms. Studies suggest that this improvement of depressive and anxiety symptoms and severity may be related to the recolonization of the gastrointestinal tract with healthy bacteria (11).…”

“…FMT is a procedure used to recolonize a patient's gut microbiota through the transplantation of feces from a donor to the recipient. A recent systematic review details the current literature surrounding the safety, e cacy and mechanisms of action for FMT (11). Though FMT has been found to be effective in many cases, it is still an arduous, expensive and invasive procedure.…”

Prescribing active transport as a planetary health intervention – benefits, challenges and recommendations

“…Exposure to the environmental microbiota changes the human microbiota [31][32][33], and understanding of the relationship between the human microbiome in a range of health conditions is receiving increased attention. There is evidence to suggest an association between the human microbiome and pain [34], fibromyalgia [35], rheumatic diseases [36], psoriatic diseases [37], multiple sclerosis [38], depression [39], anxiety [40], and cancer [41], while studies into faecal microbiota transplants have provided promising results with regards to psychiatric [42], neurological [43], and gastrointestinal conditions [44,45]. If the environmental microbiota contains microbes with human health-giving properties, then these are likely to improve human health.…”