AUTHOR=Li Xurui , Lv Chang , Song Jinxiao , Li Jianguo 

TITLE=Effect of Probiotic Supplementation on Cognitive Function and Metabolic Status in Mild Cognitive Impairment and Alzheimer's Disease: A Meta-Analysis

JOURNAL=Frontiers in Nutrition

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2021.757673

DOI=10.3389/fnut.2021.757673

ISSN=2296-861X

ABSTRACT=<p><bold>Background:</bold> Alzheimer's disease (AD) is a progressive and multifactorial neurodegenerative disease accounting for 80% of dementia worldwide.</p><p><bold>Objective:</bold> To assess the influence of probiotics on cognitive function in patients with mild cognitive impairment (MCI) and AD.</p><p><bold>Methods:</bold> PubMed, Embase, and Cochrane Library databases were searched for relevant studies.</p><p><bold>Results:</bold> Six randomized controlled trials involving 462 patients with MCI and AD were included in this meta-analysis. The probiotic administration had favorable effects on homeostasis model assessment–insulin resistance [HOMA-IR; Weighted mean difference (WMD) = −0.34, 95% confidence intervals (95% CI): −0.44 to 0.24, <italic>P</italic> &lt; 0.001, <italic>I</italic><sup>2</sup> = 0%], very low–density lipoprotein levels (VLDL; WMD = −3.71, 95% CI: −6.11 to −1.32, <italic>P</italic>=0.002,  <italic>I</italic><sup>2</sup> = 57.7%), quantitative insulin sensitivity check index (QUICKI; WMD = 0.01, 95% CI: 0.00–0.01, <italic>P</italic> = 0.003, <italic>I</italic><sup>2</sup> = 51%), and triglyceride levels (WMD = −15.65, 95% CI: −27.48 to −3.83, <italic>P</italic> = 0.009, <italic>I</italic><sup>2</sup> = 63.4%) in patients with AD. However, after Hartung-Knapp adjustment, all effects were non-significant except for HOMA-IR (MD = −0.34, 95%CI = −0.58 to −0.11). The changes in the Mini-Mental State Examination, repeatable battery for the assessment of neuropsychological status, and other biomarkers of oxidative stress, inflammation, and lipid profiles (high-sensitivity C-reactive protein, malondialdehyde, and total cholesterol) were negligible.</p><p><bold>Conclusion:</bold> The findings suggested that the consumption of probiotics had favorable effects on the HOMA-IR in patients with AD. However, the probiotic treatment did not affect cognitive function, other biomarkers of oxidative stress, and other lipid profiles.</p>