Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2025 Jul 4:48:101049.
doi: 10.1016/j.bbih.2025.101049. eCollection 2025 Oct.

Exploring the effects of faecal microbiota transplantation on cognitive function: A review of clinical trials

Sara Alaeddin  1 , Anushka Chatterjee  1 , Tara L Roberts  1   2 , Genevieve Z Steiner-Lim  3 , Slade O Jensen  1   2 , Erika Gyengesi  1 , Gerald Muench  1   3 , Vincent Ho  1
Affiliations
Review

Exploring the effects of faecal microbiota transplantation on cognitive function: A review of clinical trials

Sara Alaeddin et al. Brain Behav Immun Health. .

Abstract

Faecal Microbiota Transplantation (FMT) is a widely used microbiota-modulation technique to treat recurrent Clostridioides difficile infections (rCDI). Rodent studies and clinical trials on probiotic interventions indicate that alterations in microbiota composition may impact cognitive function. To explore whether FMT influences cognitive function in humans, we conducted a systematic search and narrative synthesis and identified 14 studies examining its effects on cognition. A variety of cohort studies, single-arm trials, case reports and randomised, placebo-controlled trials have been conducted on different neurological patient cohorts, including those with Hepatic Encephalopathy, Parkinson's Disease, dementia, and Mild Cognitive Impairment. FMT has been shown to have a significant impact on cognitive function in these populations, accompanied by alterations in microbial composition and blood markers. Interestingly, success was influenced by the route of FMT administration, indicating greater efficacy of rectal cf. oral administration on microbiome composition and cognitive improvements. However, no clinical trials have yet examined the effects of FMT on cognitively healthy individuals. FMT appears to have potential as a therapeutic strategy for cognitive impairment, though further research with larger sample sizes is needed to explore its effects in both impaired and cognitively healthy populations.

Keywords: Microbiota-gut-brain-axis; Neurodegeneration; cognitive function; faecal transplant; gut microbiome.

PubMed Disclaimer

Conflict of interest statement

The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Genevieve Z. Steiner-Lim reports financial support was provided by 10.13039/501100000925National Health and Medical Research Council (10.13039/501100000925NHMRC) Investigator Grant (APP1195709). Tara L. Roberts reports financial support was provided by Irene and Arnold Vitocco Research Fellowship. Sara Alaeddin reports financial support was provided by 10.13039/100014467South Western Sydney Local Health District, Indena and 10.13039/501100018822Western Sydney University Postgraduate Research Scholarship. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Image 1
Graphical abstract
Fig. 1
Fig. 1
Schematic illustration of the bi-directional pathways of the microbiota-gut-brain axis, facilitating communication between the gut microbiome and the brain, including neuroanatomical routes (e.g. the vagus nerve) and systemic circulation of microbial metabolites. SCFA = short chain fatty acids. Created by Sara Alaeddin in BioRender. Publication licence held by Steiner-Lim, G. Z. (2025) https://BioRender.com/v81y288.
Fig. 1
Fig. 1
PRISMA diagram of the reviewing process.
See this image and copyright information in PMC

References

    1. Amor S., Puentes F., Baker D., Van Der Valk P. Inflammation in neurodegenerative diseases. Immunology. 2010;129(2):154–169. - PMC - PubMed
    1. Anand R., Song Y., Garg S., Girotra M., Sinha A., Sivaraman A., et al. Effect of aging on the composition of fecal microbiota in donors for FMT and its impact on clinical outcomes. Dig. Dis. Sci. 2017;62:1002–1008. - PubMed
    1. Anderson J.R., Carroll I., Azcarate-Peril M.A., Rochette A.D., Heinberg L.J., Peat C., et al. A preliminary examination of gut microbiota, sleep, and cognitive flexibility in healthy older adults. Sleep Med. 2017;38:104–107. - PMC - PubMed
    1. Andrews J.S., Desai U., Kirson N.Y., Zichlin M.L., Ball D.E., Matthews B.R. Disease severity and minimal clinically important differences in clinical outcome assessments for Alzheimer's disease clinical trials. Alzheimer's Dement. 2019;5:354–363. - PMC - PubMed
    1. Backhed F., Ley R.E., Sonnenburg J.L., Peterson D.A., Gordon J.I. Host-bacterial mutualism in the human intestine. science. 2005;307(5717):1915–1920. - PubMed

LinkOut - more resources