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

Background

Alzheimer's disease (AD) is a progressive and multifactorial neurodegenerative disease accounting for 80% of dementia worldwide.

Objective

To assess the influence of probiotics on cognitive function in patients with mild cognitive impairment (MCI) and AD.

Methods

PubMed, Embase, and Cochrane Library databases were searched for relevant studies.

Results

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, P < 0.001, I 2 = 0%], very low-density lipoprotein levels (VLDL; WMD = -3.71, 95% CI: -6.11 to -1.32, P=0.002, I 2 = 57.7%), quantitative insulin sensitivity check index (QUICKI; WMD = 0.01, 95% CI: 0.00-0.01, P = 0.003, I 2 = 51%), and triglyceride levels (WMD = -15.65, 95% CI: -27.48 to -3.83, P = 0.009, I 2 = 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.

Conclusion

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.