Cognition enhancing effect of rosemary (Rosmarinus officinalis L.) in lab animal studies: a systematic review and meta-analysis

Patients with mild cognitive impairment eventually progress to Alzheimer's disease (AD) causing a strong impact on public health. Rosmarinus officinalis has long been known as the herb of remembrance and can be a potential cognition enhancer for AD. The aim of this review was to summarize the qualitative and quantitative aspects of R. officinalis and its active constituents in enhancing cognition. A structured search was conducted on Google Scholar and PubMed to find relevant studies that assessed the effect of R. officinalis extract or any of its active constituents on cognitive performance in animals. The following information was extracted from each study: 1) article information; 2) characteristics of study animals; 3) type of intervention: type, dose, duration, and frequency of administration of R. officinalis; and 4) type of outcome measure. Data were analyzed using Review Manager and meta-analysis was performed by computing the standardized mean difference. Twenty-three studies were selected for qualitative analysis and fifteen for meta-analysis. From the fifteen included papers, 22 with 35 comparisons were meta-analyzed. Effect sizes for intact and cognitively impaired animals were 1.19 (0.74, 1.64) and 0.57 (0.19, 0.96), indicating a positive effect on both groups. The subgroup analyses showed substantial unexplained heterogeneity among studies. Overall, R. officinalis improved cognitive outcomes in normal and impaired animals, and results were robust across species, type of extract, treatment duration, and type of memory. However, studies had a considerable amount of heterogeneity, and subgroup analyses failed to find any heterogeneity moderator.

轻度认知障碍患者最终可进展为阿尔茨海默病（Alzheimer's disease, AD），对公共健康造成显著负面影响。迷迭香（Rosmarinus officinalis）长期以来被冠以“记忆之草”的美誉，有望成为阿尔茨海默病潜在的认知增强剂。本综述旨在总结迷迭香及其活性成分改善认知功能的定性与定量研究证据。研究团队在Google Scholar与PubMed数据库中开展结构化检索，筛选评估迷迭香提取物或其任一活性成分对动物认知表现影响的相关研究。从每项纳入研究中提取以下四类信息：1）文献基本信息；2）实验动物的特征参数；3）干预措施详情：包括迷迭香的给药类型、剂量、干预时长与给药频率；4）结局指标类型。数据分析采用Review Manager（RevMan）软件完成，并通过计算标准化均差（standardized mean difference）进行Meta分析。最终共纳入23项研究进行定性分析，15项研究用于Meta分析；从上述15篇纳入文献中，共纳入22项独立实验、35组对照数据开展Meta分析。正常认知完整动物与认知受损动物的效应量分别为1.19（95%置信区间：0.74, 1.64）与0.57（95%置信区间：0.19, 0.96），提示迷迭香对两类动物均具有正向认知改善作用。亚组分析显示，各纳入研究间存在显著的未解释异质性。总体而言，迷迭香可改善正常及认知受损动物的认知结局，且该研究结果在不同受试物种、提取物类型、干预疗程与记忆类型中均表现稳健。但现有研究间异质性较高，且亚组分析未发现可解释该异质性的调节因素。