Can ginkgo biloba extract prevent dementia among elderly?
Date of publication of the randomized controlled trial: November 2008
Design
Randomized controlled trial (RCT).
Participants
3069 older adult participants (mean age: 79.1 years, male %: 53.8%) with normal cognition or mild cognitive impairment.
Intervention
Twice-daily dose of 120 mg Ginkgo biloba extract.
Comparator
Comparison: Ginkgo biloba extract versus placebo.
Major Outcomes
Outcome 1: Overall all-cause dementia incidence per 100 person-years;
Outcome 2: Hazard ratio (HR) of all-cause dementia.
Dementia cases were determined by expert panel consensus.
Settings
This trial was performed in an outpatient setting.
Comparison    Ginkgo biloba extract versus placebo
Main Results
Compared to placebo, Ginkgo biloba extract do not have significant effect on the overall all-cause dementia incidence (p=0.21) among elderly. The hazard ratio (HR) for Ginkgo biloba extract compared to placebo was also insignificant (HR: 1.12, 95% CI: 0.94 to 1.33) among elderly participants.
Comparison: Ginkgo biloba extract versus placebo among elderly
Outcome No. of studies (Total number of participants) Dementia rate (%)/ No. of participants Heterogeneity test ( I2) p value Overall quality of evidence*
Intervention Comparator
1 1 (3069) 3.27/ 1545 2.94/ 1524 Not applicable as there is only 1 study. 0.21 Moderate
Outcome No. of studies (Total number of participants) Hazard ratio (95% CI) / No. of participants Heterogeneity test ( I2) p value Overall quality of evidence*
2 1 (3069) 1.12 (0.94 to 1.33)/ 3069 Not applicable as there is only 1 study. 0.21 Moderate
Keys: CI= confidence interval.
Comparison    Ginkgo biloba extract versus placebo
Main Results
Compared to placebo, Ginkgo biloba extract do not have significant effect on the overall all-cause dementia incidence (p=0.21) among elderly. The hazard ratio (HR) for Ginkgo biloba extract compared to placebo was also insignificant (HR: 1.12, 95% CI: 0.94 to 1.33) among elderly participants.
Comparison: Ginkgo biloba extract versus placebo among elderly
Outcome 1
No. of studies (Total number of participants) 1 (3069)
Dementia rate (%)/ No. of participants Intervention 3.27/ 1545
Comparator 2.94/ 1524
p value 0.21
Overall quality of evidence* Moderate
Outcome 2
No. of studies (Total number of participants) 1 (3069)
Hazard ratio (95% CI) / No. of participants 1.12 (0.94 to 1.33)/ 3069
p value 0.21
Overall quality of evidence* Moderate
Keys: CI= confidence interval.
Conclusion
Benefits
Compared to placebo, Ginkgo biloba extract is not significantly more effective in preventing dementia among elderly. For Outcome 1-2, the overall quality of evidence is moderate. Further research is fairly likely to have an important impact on our confidence in this estimate of effect.
Harms
The adverse event profiles for Ginkgo biloba extract and placebo were similar and there were no statistically significant differences in the incidence of serious adverse events.
Link to Original Article
https://www.ncbi.nlm.nih.gov/pubmed/19017911
The synopsis is based on the following article:
DeKosky ST, Williamson JD, Fitzpatrick AL, Kronmal RA, Ives DG, Saxton JA, et al. Ginkgo biloba for prevention of dementia: a randomized controlled trial. JAMA. 2008 Nov 19;300(19):2253-62.


* Interpretation of quality assessment results:
• Very low: Further research is most likely to have an important impact on our confidence in this estimate of effect.
• Low: Further research is likely to have an important impact on our confidence in this estimate of effect.
• Moderate: Further research is fairly likely to have an important impact on our confidence in this estimate of effect.
• High: Further research is unlikely to have an important impact on our confidence in this estimate of effect.
• Very high: Further research is most unlikely to have an important impact on our confidence in this estimate of effect.

Details of assessment method can be found at Chung VC, Wu XY, Ziea ET, Ng BF, Wong SY, Wu JC. Assessing internal validity of clinical evidence on effectiveness of CHinese and integrative medicine: Proposed framework for a CHinese and Integrative Medicine Evidence RAting System (CHIMERAS). European Journal of Integrative Medicine. 2015 Aug 31;7(4):332-41.