Background: In recent years, the existence of the gut-brain axis and the impact of intestinal microbiota on brain function has received much attention. Accumulated evidence has prompted the postulation of the infectious hypothesis underlying or facilitating neurodegenerative diseases, such as Alzheimer's disease. Under this hypothesis, intervention with probiotics could be useful at a preventive and therapeutic level.
Objective: The objective of this systematic review is to reveal a benefit of improved cognitive function following the use of probiotics in individuals with mild cognitive impairment.
Methods: We searched bibliographic databases and analyzed in detail the evidence and methodological quality of five recent randomized, double-blind, placebo-controlled clinical trials using the Cochrane Tool and the SIGN checklist.
Results: Overall, and with satisfactory methodological quality, the evaluated studies support the use of probiotics as a weapon to slow the progression of cognitive decline in subjects with mild cognitive impairment. The reviewed literature also indicates that maximum benefit of probiotics is found in subjects with incipient cognitive dysfunction and has no effect in those with advanced disease or absence of disease.
Conclusion: These results support the intervention with probiotics, especially as a preventive approach. However, caution is required in the interpretation of the results as microbiota has not been evaluated in all studies, and further large-scale research with a prolonged study period is necessary to ensure the translatability of the results into real practice.
Keywords: Alzheimer’s disease; brain-gut axis; cognitive dysfunction; gastrointestinal microbiome; probiotics.