Ginkgo biloba for cognitive impairment and dementia
Editorial Group: Cochrane Dementia and Cognitive Improvement Group
Published Online: 21 JAN 2009
Assessed as up-to-date: 25 MAR 2008
Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
How to Cite
Birks J, Grimley Evans J. Ginkgo biloba for cognitive impairment and dementia. Cochrane Database of Systematic Reviews 2009, Issue 1. Art. No.: CD003120. DOI: 10.1002/14651858.CD003120.pub3.
- Publication Status: Edited (no change to conclusions)
- Published Online: 21 JAN 2009
Products of the maidenhair tree, Ginkgo biloba, have long been used in China as a traditional medicine for various disorders of health. A standardized extract is widely used in the West for the treatment of a range of conditions including memory and concentration problems, confusion, depression, anxiety, dizziness, tinnitus and headache. The mechanisms of action are thought to reflect the action of several components of the extract and include increasing blood supply by dilating blood vessels, reducing blood viscosity, modification of neurotransmitter systems, and reducing the density of oxygen free radicals.
To assess the efficacy and safety of Ginkgo biloba for dementia or cognitive decline.
The Specialized Register of the Cochrane Dementia and Cognitive Improvement Group (CDCIG), The Cochrane Library, MEDLINE, EMBASE, PsycINFO, CINAHL and LILACS were searched on 20 September 2007 using the terms: ginkgo*, tanakan, EGB-761, EGB761, "EGB 761" and gingko*. The CDCIG Specialized Register contains records from all major health care databases (The Cochrane Library, MEDLINE, EMBASE, PsycINFO, CINAHL, LILACS) as well as from many trials databases and grey literature sources.
Randomized, double-blind studies, in which extracts of Ginkgo biloba at any strength and over any period were compared with placebo for their effects on people with acquired cognitive impairment, including dementia, of any degree of severity.
Data collection and analysis
Data were extracted from the published reports of the included studies, pooled where appropriate and the treatment effects or the risks and benefits estimated.
36 trials were included but most were small and of duration less than three months. Nine trials were of six months duration (2016 patients). These longer trials were the more recent trials and generally were of adequate size, and conducted to a reasonable standard. Most trials tested the same standardised preparation of Ginkgo biloba, EGb 761, at different doses, which are classified as high or low. The results from the more recent trials showed inconsistent results for cognition, activities of daily living, mood, depression and carer burden. Of the four most recent trials to report results three found no difference between Ginkgo biloba and placebo, and one reported very large treatment effects in favour of Ginkgo biloba.
There are no significant differences between Ginkgo biloba and placebo in the proportion of participants experiencing adverse events.
A subgroup analysis including only patients diagnosed with Alzhiemer's disease (925 patients from nine trials) also showed no consistent pattern of any benefit associated with Ginkgo biloba.
Ginkgo biloba appears to be safe in use with no excess side effects compared with placebo. Many of the early trials used unsatisfactory methods, were small, and publication bias cannot be excluded. The evidence that Ginkgo biloba has predictable and clinically significant benefit for people with dementia or cognitive impairment is inconsistent and unreliable.
Plain language summary
There is no convincing evidence that Ginkgo biloba is efficacious for dementia and cognitive impairment
Ginkgo biloba appears to be safe in use with no excess adverse effects compared with placebo. Many of the early trials used unsatisfactory methods, were small, and publication bias cannot be excluded. Overall, evidence that Ginkgo has predictable and clinically significant benefit for people with dementia or cognitive impairment is inconsistent and unreliable. Of the four most recent trials to report results, three found no difference between Ginkgo biloba and placebo, and one reported very large treatment effects in favour of Ginkgo biloba.
在2007年9月20日使用The Specialized Register of the Cochrane Dementia and Cognitive Improvement Group (CDCIG)、Cochrane Library、MEDLINE、EMBASE、PsycINFO、CINAHL和 LILACS資料庫針對「ginkgo*, tanakan, EGB761, EGB761, "EGB 761" 和 gingko*」進行檢索， CDCIG資料庫包含所有主要健康照顧資料庫(The Cochrane Library, MEDLINE, EMBASE, PsycINFO, CINAHL, LILACS)、很多試驗資料庫和很多灰色文獻來源。
有36個試驗被納入，但大多是小型的和治療時間少於三個月。有9個持續了6個月的試驗 (2016位病患)，這些較長期的試驗大部份都是最近的試驗且納錄足夠的病患以及執行合理化的標準。這些試驗都是使用相同標準化製備的銀杏萃取物(EGb 761)，但依劑量不同可分成高與低劑量。最近試驗結果顯示在認知功能，日常生活活動性，情緒，憂鬱和照顧者負擔上的結果是不一致的。最近4個試驗中，有3個試驗認為銀杏和安慰劑無明顯差異，有1個試驗指出銀杏具有很好的治療效果。銀杏和安慰劑對受試者所引發的不良事件並沒有差異。有一個次分組試驗只收錄被診斷患有阿茲海默症患者(由個試驗納入的925名患者)，其結果也顯示銀杏並無確切的療效。
此翻譯計畫由臺灣國家衛生研究院(National Health Research Institutes, Taiwan)統籌。