Quality assessment of studies using Jadad scale.

Background and objectivesIncreasing evidence indicates a link between obesity and cognitive impairment. Furthermore, there is limited literature regarding the effect of polyphenols, a plant derived compounds, on executive functioning in an overweight/obese population at-risk of cognitive impairment. The aim of the present systematic review and meta-analysis of randomized controlled trials is to examine the effect of polyphenol supplementation on executive functions in overweight and/or obese populations at risk of cognitive impairment.MethodsA comprehensive literature search was conducted from inception to March 2023 using four electronic databases: PubMed/Medline, PsycInfo, Scopus and Cochrane trials library. Published primary research studies in English that compared the effect of polyphenols with placebo on executive function in overweight/obese adults were considered eligible for the meta-analysis. Jadad scale was used for the methodological quality rating of the included studies. Hedges g with 95% confidence intervals (CI) for endpoints were calculated using random effect model where applicable. Rosenthal’s Fail-safe N, funnel plots, the Begg and Mazumdar’s rank correlation test (Kendall’s S statistic P-Q), Egger’s linear regression test, and Duval and Tweedie’s trim-and-fill test were identified for potential use as appropriate, to examine publication bias. Sensitivity analysis was conducted to examine the robustness of the results.Results and conclusionA total of 23 RCT studies involving N = 1,976 participants were included in the review. The results of the meta-analysis revealed a non-significant effect for polyphenol supplementation on executive function (g = 0.076, CI = -0.018 to 0.170). Observations from primary studies within the meta-analysis showed a potential positive effect of polyphenol supplementation in a younger population at-risk of cognitive impairment and it is recommended to investigate this further in future studies. Moreover, the variability of the tasks used to examine executive functions as well as the adequate reporting of supplement’s phenolic composition is a limitation that future work should also consider.研究背景与目的：越来越多的研究证据表明，肥胖与认知损害之间存在关联。此外，目前针对植物来源多酚类化合物（polyphenols）对存在认知损害风险的超重/肥胖人群执行功能影响的相关研究文献较为匮乏。本项针对随机对照试验（RCT）的系统评价与荟萃分析，旨在探究多酚补充干预对存在认知损害风险的超重及/或肥胖人群执行功能的影响。 方法：本研究依托PubMed/Medline、PsycInfo、Scopus及Cochrane临床试验库四大电子数据库，自数据库建库起至2023年3月开展全面文献检索。本荟萃分析纳入以英语发表的、对比多酚与安慰剂对超重/肥胖成人执行功能影响的原创性研究。采用Jadad量表对纳入研究的方法学质量进行评级。针对各研究终点，采用随机效应模型（适用时）计算Hedges g值及95%置信区间（CI）。酌情采用Rosenthal失效安全数、漏斗图、Begg-Mazumdar秩相关检验（Kendall's S统计量P-Q）、Egger线性回归检验及Duval-Tweedie剪补法等手段，检测潜在的发表偏倚。通过敏感性分析检验研究结果的稳健性。 结果与结论：本系统评价共纳入23项随机对照试验（RCT），涉及1976名受试者。荟萃分析结果显示，多酚补充干预对受试者执行功能的改善未达到统计学显著性（g=0.076，95%CI=-0.018~0.170）。荟萃分析所纳入的原创性研究结果提示，多酚补充干预对存在认知损害风险的年轻人群或存在积极作用，建议未来开展相关研究进一步验证这一结论。此外，当前用于评估执行功能的任务异质性较强，且补充剂的多酚成分报告不够充分，这些均为未来研究需关注的局限性。