There is no convincing evidence that Ginkgo biloba is efficacious for dementia and cognitive impairment

Birks J, Grimley Evans J

Published Online:

April 15, 2009

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.

Abstract (click to read)

Background:

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.

Objectives:

To assess the efficacy and safety of Ginkgo biloba for dementia or cognitive decline.

Search strategy:

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.

Selection criteria:

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.

Main results:

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.

Authors' conclusions:

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.

This record should be cited as:

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

Assessed as up to date:

March 26, 2008

Find the research

Get full text at The Cochrane Library

Primary Review Group:

Dementia and Cognitive Improvement Group

PEARLS - Practical Evidence About Real Life Situations (click to read)

Clinical question:

Is Ginkgo biloba an effective treatment for cognitive impairment and dementia?

Bottom line:

There is no convincing evidence that Ginkgo biloba is efficacious for cognitive impairment and dementia.

Caveat:

Many of the early trials which suggested beneficial effects were small, used unsatisfactory methods, and publication bias cannot be excluded. Two of the most recent trials which were also amongst the largest trials, found no difference between placebo and Ginkgo biloba.

Context:

Extracts from the leaves of the maidenhair tree, Ginkgo biloba, have long been used in China as a traditional medicine for various conditions. A standardized extract is widely used for the treatment of a range of conditions, including memory and concentration problems, confusion, depression, anxiety, tinnitus and headache.

Cochrane Systematic Review:

Birks J et al. Ginkgo biloba for cognitive impairment and dementia. Cochrane Database of Systematic Reviews, 2007. Issue 2, Art. No: CD003120. DOI:10.1002/14651858.CD003120.pub2. This review contains 35 studies ranging in size from 14 to 513 participants.

Authored by:

Brian R McAvoy

Cochrane Primary Health Care Field

Health topics:

Mental health > Dementia & cognition > Interventions aimed at interrupting disease processes

Mental health > Dementia & cognition > Prevention: cognitively impaired

Neurology > Dementia & cognition > Interventions aimed at interrupting disease processes

Neurology > Dementia & cognition > Prevention: cognitively impaired

Complementary & alternative medicine > Mental health > Dementia & cognition

Complementary & alternative medicine > Neurology > Dementia & cognition

In the News

Irish Times series on the efficacy of herbal remedies frequently quotes Cochrane evidence

"Does it work?", an online series by Dónal O'Mathúna in The Irish Times, explores the efficacy of herbal remedies frequently quoting Cochrane evidence, i.e. on ginko biloba (article, review), hawthorn (article, review) and vitamin B12 (article, review).

Newseek article quotes Cochrane evidence

A Newsweek article discusses the evidence for a range of alternative treatments, including Ginkgo biloba quoting Cochrane evidence. [Go to review]

NY Times quotes Cochrane evidence

The New York Times reports on a recent trial of Ginkgo Biloba for dementia quoting relevant Cochrane evidence. [Go to review]

Cochrane Summaries^beta

Independent high-quality evidence for health care decision making

There is no convincing evidence that Ginkgo biloba is efficacious for dementia and cognitive impairment

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