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Ginkgo biloba for cognitive impairment and dementia.

Abstract

BACKGROUND

Extracts of the leaves 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 prescribed 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

Trials were identified on 10 October 2006 through a search of the Cochrane Dementia and Cognitive Improvement Group's Specialized Register which contains records from all main medical databases (MEDLINE, EMBASE, CINAHL, PsycINFO, SIGLE, LILACS), from ongoing trials databases such as Clinicaltrials.gov and Current Controlled Trials and many other sources. The search terms used were ginkgo*, tanakan, EGB-761, EGB761, "EGB 761" and gingko*.

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

Clinical global improvement as assessed by the physician, was dichotomized between participants who showed improvement or were unchanged and those who were worse. There are benefits associated with Ginkgo (dose greater than 200 mg/day) at 24 weeks (207/276 compared with 178/273, OR 1.66, 95% CI 1.12 to 2.46, P=.001) (2 studies), but not for the lower dose. Cognition shows benefit for Ginkgo (any dose) at 12 weeks (SMD -0.65, 95% CI -1.22 to -0.09 P=0.02, 5 studies) but not at 24 weeks. Five studies assessed activities of daily living (ADLs), using different scales. Some scales are more comprehensive than just ADLs. The results show benefit for Ginkgo (dose less than 200 mg/day) compared with placebo at 12 weeks (MD -5.0, 95% CI -7.88, -2.12, p=0.0007, one study), and at 24 weeks (SMD -0.16, 95% CI -0.31 to -0.01, p=0.03, 3 studies) but there are no differences at the higher dose. No study assessed mood and function separately, but one study used the ADAS-Noncog, which assesses function over several domains, but not cognitive function. There was no difference between Ginkgo and placebo. There are no significant differences between Ginkgo and placebo in the proportion of participants experiencing adverse events. There are no data available on Quality of Life, measures of depression or dependency.

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 we cannot exclude publication bias. The evidence that Ginkgo has predictable and clinically significant benefit for people with dementia or cognitive impairment is inconsistent and unconvincing.

Authors+Show Affiliations

University of Oxford, Nuffield Department of Clinical Medicine, CDCIG Room 5802, John Radcliffe Hospital, Oxford, UK, OX3 9DU. jacqueline.birks@geratol.ox.ac.ukNo affiliation info available

Pub Type(s)

Journal Article
Meta-Analysis
Review
Systematic Review

Language

eng

PubMed ID

17443523

Citation

Birks, J, and J Grimley Evans. "Ginkgo Biloba for Cognitive Impairment and Dementia." The Cochrane Database of Systematic Reviews, 2007, p. CD003120.
Birks J, Grimley Evans J. Ginkgo biloba for cognitive impairment and dementia. Cochrane Database Syst Rev. 2007.
Birks, J., & Grimley Evans, J. (2007). Ginkgo biloba for cognitive impairment and dementia. The Cochrane Database of Systematic Reviews, (2), CD003120.
Birks J, Grimley Evans J. Ginkgo Biloba for Cognitive Impairment and Dementia. Cochrane Database Syst Rev. 2007 Apr 18;(2)CD003120. PubMed PMID: 17443523.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Ginkgo biloba for cognitive impairment and dementia. AU - Birks,J, AU - Grimley Evans,J, Y1 - 2007/04/18/ PY - 2007/4/20/pubmed PY - 2007/7/18/medline PY - 2007/4/20/entrez SP - CD003120 EP - CD003120 JF - The Cochrane database of systematic reviews JO - Cochrane Database Syst Rev IS - 2 N2 - BACKGROUND: Extracts of the leaves 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 prescribed 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: Trials were identified on 10 October 2006 through a search of the Cochrane Dementia and Cognitive Improvement Group's Specialized Register which contains records from all main medical databases (MEDLINE, EMBASE, CINAHL, PsycINFO, SIGLE, LILACS), from ongoing trials databases such as Clinicaltrials.gov and Current Controlled Trials and many other sources. The search terms used were ginkgo*, tanakan, EGB-761, EGB761, "EGB 761" and gingko*. 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: Clinical global improvement as assessed by the physician, was dichotomized between participants who showed improvement or were unchanged and those who were worse. There are benefits associated with Ginkgo (dose greater than 200 mg/day) at 24 weeks (207/276 compared with 178/273, OR 1.66, 95% CI 1.12 to 2.46, P=.001) (2 studies), but not for the lower dose. Cognition shows benefit for Ginkgo (any dose) at 12 weeks (SMD -0.65, 95% CI -1.22 to -0.09 P=0.02, 5 studies) but not at 24 weeks. Five studies assessed activities of daily living (ADLs), using different scales. Some scales are more comprehensive than just ADLs. The results show benefit for Ginkgo (dose less than 200 mg/day) compared with placebo at 12 weeks (MD -5.0, 95% CI -7.88, -2.12, p=0.0007, one study), and at 24 weeks (SMD -0.16, 95% CI -0.31 to -0.01, p=0.03, 3 studies) but there are no differences at the higher dose. No study assessed mood and function separately, but one study used the ADAS-Noncog, which assesses function over several domains, but not cognitive function. There was no difference between Ginkgo and placebo. There are no significant differences between Ginkgo and placebo in the proportion of participants experiencing adverse events. There are no data available on Quality of Life, measures of depression or dependency. 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 we cannot exclude publication bias. The evidence that Ginkgo has predictable and clinically significant benefit for people with dementia or cognitive impairment is inconsistent and unconvincing. SN - 1469-493X UR - https://www.unboundmedicine.com/medline/citation/17443523/full_citation L2 - https://doi.org/10.1002/14651858.CD003120.pub2 DB - PRIME DP - Unbound Medicine ER -