Published online Oct 21, 2021. doi: 10.3748/wjg.v27.i39.6715
Peer-review started: February 25, 2021
First decision: April 18, 2021
Revised: May 12, 2021
Accepted: September 2, 2021
Article in press: September 2, 2021
Published online: October 21, 2021
Processing time: 236 Days and 19.6 Hours
Due to the global population aging, cognitive impairments will affect approximately 115 million people by 2050. Since current therapies only attempt to counterbalance cognitive disorders, many recent studies recently highlighted the central role of the gut microbiota in brain health.
The pathogenesis of several cognitive disorders is still not fully understood; however, it has been recently established that a dysregulated gut-brain axis communication is associated with the onset and persistence of neurodegenerative diseases. Thus, gut microbiota manipulation could restore a functional gut-brain axis improving cognitive functions.
Since the evidence derived from human randomized clinical trials (RCTs) is currently limited, the main purpose of this systematic review was to detect the currently available RCTs, to define better the effects of probiotics, prebiotics, and fecal microbiota transplant (FMT) on cognitive functions.
We systematically searched Embase, Medline/PubMed, Cochrane Library, central and clinicaltrials.gov databases with a combination of comprehensive terms related to cognition and gut microbiota manipulation. Then, we carefully reviewed and synthesized the data by types of study design and setting, characteristics of the studied population, kind of the intervention (strain type or mixture type, dosage and frequency of administration), control treatment, inclusion and exclusion criteria, follow-up duration, and cognitive or memory outcomes.
The analysis of the 23 included in our systematic review highlighted that, although the different type and posology of administration and the various cognitive tests and questionnaires adopted, both probiotics supplementation and FMT improved the cognitive functions in most of healthy people and patients affected by different neurological pathologies.
The gut microbiota manipulation could represent a good strategy to counteract gut dysbiosis and so ameliorate cognitive dysfunction.
The supplementation of probiotics and FMT could represent a non-invasive successful strategy to restore gut eubiosis and enhance cognitive functions in healthy people and patients with different neurological/neurodegenerative diseases.