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 Diagnostic and statistical manual of mental disorders have also been linked to various psychiatric illnesses such as depression, anxiety, substance abuse, autism spectrum disorder, 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 = 8), preclinical with human donors (n = 9), or entirely preclinical (n = 11). 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. Registered on PROSPERO, IRD: CRD42019126795.

Serotonin Reuptake Inhibitors and the Gut Microbiome: Significance of the Gut Microbiome in Relation to Mechanism of Action, Treatment Response, Side Effects, and Tachyphylaxis

“…Initial different compositions of the microbiome may depend on the mode of delivery (vaginal vs. caesarian section), whether the child is breastfed, skin-to-skin contact, different types of diet, etc. A dynamic process then proceeds toward a gradual stabilization of the gut microbiome during adulthood ( 42 ). While the host genome is not easily manipulated, different dietary regimes are known to provide ways of manipulating the more plastic microbiome.…”

“…This has proven to be a highly effective way of treating a type of severely disabling chronic diarrhea due to colonization of clostridium difficile ( 45 ). It has also been evaluated in pre-clinical as well as a few small clinical trials in relation to neuropsychiatric symptoms ( 42 ). However, this is a burgeoning field and more research is warranted in regards to what precisely constitutes a healthy gut microbiome.…”

Western Diet: Implications for Brain Function and Behavior

“…In this regard, clinical trials with FMT for major depression and/or anxiety have reported no effects or return to baseline depression scores after 3, 5, or 6 months (Mizuno et al, 2017;Mazzawi et al, 2018;Huang et al, 2019). The main limitation of clinical trials of FMT for mental disorders is the small sample size, the long-term efficacy, and the still undefined concept of "healthy microbiota" with wide variations in the taxonomic composition of gut microbiota among "healthy" individuals (Chinna Meyyappan et al, 2020). In this regard, FMT for obesity and its metabolic effects has not been successful in recent randomized clinical trials despite host microbiota engraftment (Yu et al, 2020) nor reduced BMI in obese patients (Allegretti et al, 2020).…”

Adiposity in Depression or Depression in Adiposity? The Role of Immune-Inflammatory-Microbial Overlap

“…However, discrepant data regarding the health benefits of probiotics on metabolic diseases have been reported which may partially result from the heterogeneity of therapies and protocols. Finally, it is possible that FMT may be of value in the treatment of psychiatric disorders and MetS, but the data is limited [105,106], and further research with larger sample sizes and stronger scientific design is necessary. In addition, a growing number of medications have been found to affect the gut microbiota [107].…”