Effects of probiotic supplementation on cognitive function in elderly: A systematic review and Meta-analysis

Abstract

Objectives

Probiotic supplementation has been linked to changes in cognitive function via the gut-brain axis (GBA). However, the current literature lacks a comprehensive review regarding this matter in the elderly population.

Method

Electronic databases including Medline (PubMed), Scopus, Embase, Web of Science, and Google Scholar were comprehensively searched for identifying studies that assessed the effects of probiotics on the cognitive function of the elderly published until July 2020. Articles were critically reviewed and if met the inclusion criteria, entered the study

Results

Among a total of 1374 studies, 10 were eligible for meta-analysis. No significant alteration was found in the cognition of the elderly (SMD=-0.04; 95% CI [- 1.07,0.98]; P = 0.93). There was a nonsignificant increase in the level of brain-derived neurotrophic factor (SMD = 0.58; 95% CI [-1.40,2.56]; P = 0.56) and a nonsignificant reduction in malondialdehyde levels (SMD=-0.44; 95% CI [-1.07,0.19]; P = 0.17). Levels of total antioxidant capacity (SMD = 39.93; 95% CI [2.92,76.95]; P = 0.03) and total glutathione (SMD = 61.51; 95% CI [12.39,110.62]; P = 0.01) significantly increased. A significant reduction was also noted in total cholesterol levels (SMD=-4.23; 95% CI [-8.32, −0.14]; P = 0.04).

Conclusion

Our study did not support the hypothesis of the positive effect of probiotics on cognitive function in the elderly population; which might be due to the heterogeneity across the studies.

Graphical Abstract

Keywords:

• Elderly
• probiotic
• cognitive function
• systematic review

Acknowledgements

The research protocol was approved and supported by Student Research Committee, Tabriz University of Medical Sciences (Registration Code: 62252).

Disclosure statement

The authors declare no conflicts of interest.

Statement of authorship

S.S and F.T designed the research; F.T and A.S conducted the literature searches; S.S, F.T and A.M selected the studies and screened the abstracts, selected the studies meeting the inclusion criteria; F.T and A.S assessed the study quality; F.T and S.S extracted the data; M.M and F.T performed statistical analysis; F.T drafted the initial manuscript,

S.S and A.M reviewed and revised the manuscript. All authors read and approved the final manuscript.

Data availability statement

All the data is available upon reasonable request.

Additional information

Funding

This work was supported by the Deputy for Research of Tabriz University of Medical