Effects of Dihuang Yinzi Decoction on Alzheimer’s Disease: A Systematic Review and Meta-Analysis

Objective: The aim of this study was to systematically evaluate the therapeutic effects of Dihuang Yinzi decoction on Alzheimer’s disease (AD) and provide a medical evidence-based clinical application of traditional Chinese medicine (TCM). Methods: A comprehensive search was conducted across multiple databases, including PubMed, Embase, Cochrane Library, China National Journals Full-text Database, VIP Database for Chinese Technical Periodicals, Wan Fang database, and SinoMed database, to collect clinical randomized controlled trials of Dihuang Yinzi decoction in the treatment of AD. Strict literature screening was performed based on predefined inclusion and exclusion criteria. The Cochrane Collaboration risk of bias assessment tool and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system recommendation-level method was used to assess the quality of the included studies. Review Manager 5.4 and Stata 17 software were used for data synthesis and processing, while GRADE Profiler 3.6 software was used to evaluate the quality of evidence for outcome indicators (risk ratio, standardized mean difference, and weighted mean difference). Results: A total of 11 studies involving 798 patients met the inclusion criteria. Dihuang Yinzi decoction, whether used alone or in combination with conventional Western medicine, demonstrated superior efficacy compared to conventional Western medicine alone in improving the clinical effective rate, TCM syndrome score, activity of daily living score, Mini-Mental State Examination score, and Hasegawa Dementia Scale score in AD treatment. Furthermore, it exhibited a favorable safety profile. However, the GRADE evidence quality rating for the included studies was low. Conclusions: Dihuang Yinzi decoction, either used alone or in combination with conventional Western medicine, shows promising results in enhancing cognitive and memory functions as well as the self-care ability of patients with AD. However, the low GRADE evidence quality rating highlights the need for focused advancements in the planning and execution of clinical randomized controlled trials during future research attempts.