Can ginkgo biloba extract prevent cognitive decline among elderly?
Date of publication of the randomized controlled trial: December 2009
Design
Randomized controlled trial (RCT).
Participants
3069 community-dwelling older adults (mean age: 79.1 years, male %: 53.8%) without dementia, defined by the Diagnostic and Statistical Manual of Mental Disorders (4th Edition) or a score ≤0.5 on Clinical Dementia Rating (CDR).
Intervention
Twice-daily dose of 120 mg Ginkgo biloba extract for a median of 6.1 years.
Comparator
Comparison: Ginkgo biloba extract versus placebo.
Major Outcomes
Outcome 1: Annual rate of decline in memory;
Outcome 2: Annual rate of decline in attention;
Outcome 3: Annual rate of decline in visuospatial abilities;
Outcome 4: Annual rate of decline in language;
Outcome 5: Annual rate of decline in executive functions.
All outcomes were measured by a battery of neuropsychological evaluations such as Modified Mini-Mental State Examination, Alzheimer Disease Assessment Scale and Clinical Dementia Rating.
Settings
This trial was performed in an outpatient setting.
Comparison    Ginkgo biloba extract versus placebo
Main Results
Compared to placebo, Ginkgo biloba do not have significant effect on the annual rate of decline in memory (overall difference in z score: 0.034, 95% CI: -0.019 to 0.086), attention (overall difference in z score: 0.037, 95% CI: -0.012 to 0.086), visuospatial abilities (overall difference in z score: 0.038, 95% CI: -0.017 to 0.093), language (overall difference in z score: -0.041, 95% CI: -0.093 to 0.011) and executive functions (overall difference in z score: 0.013, 95% CI: -0.042 to 0.069).
Comparison: Ginkgo biloba extract versus placebo among elderly.
Outcomes No. of studies (Total number of participants) Annual rate of changes in z scores / No. of participants Heterogeneity test ( I2) Overall difference in z score (95% CI) Overall quality of evidence*
Intervention Comparator
1 1 (3069) 0.043/ 1545 0.041/ 1524 Not applicable as there is only 1 study. 0.034 (-0.019 to 0.086) Moderate
2 1 (3069) 0.043/ 1545 0.048/ 1524 Not applicable as there is only 1 study. 0.037 (-0.012 to 0.086) Moderate
3 1 (3069) 0.107/ 1545 0.118/ 1524 Not applicable as there is only 1 study. 0.038 (-0.017 to 0.093) Moderate
4 1 (3069) 0.045/ 1545 0.041/ 1524 Not applicable as there is only 1 study. -0.041 (-0.093 to 0.011) Moderate
5 1 (3069) 0.092/ 1545 0.089/ 1524 Not applicable as there is only 1 study. 0.013 (-0.042 to 0.069) Moderate
Keys: CI= confidence interval.
Comparison    Ginkgo biloba extract versus placebo
Main Results
Compared to placebo, Ginkgo biloba do not have significant effect on the annual rate of decline in memory (overall difference in z score: 0.034, 95% CI: -0.019 to 0.086), attention (overall difference in z score: 0.037, 95% CI: -0.012 to 0.086), visuospatial abilities (overall difference in z score: 0.038, 95% CI: -0.017 to 0.093), language (overall difference in z score: -0.041, 95% CI: -0.093 to 0.011) and executive functions (overall difference in z score: 0.013, 95% CI: -0.042 to 0.069).
Comparison: Ginkgo biloba extract versus placebo among elderly.
Outcomes 1 2 3 4 5
No. of studies (Total number of participants) 1 (3069) 1 (3069) 1 (3069) 1 (3069) 1 (3069)
Annual rate of changes in z scores / No. of participants Intervention 0.043/ 1545 0.043/ 1545 0.107/ 1545 0.045/ 1545 0.092/ 1545
Comparator 0.041/ 1524 0.048/ 1524 0.118/ 1524 0.041/ 1524 0.089/ 1524
Overall difference in z score (95% CI) 0.034 (-0.019 to 0.086) 0.037 (-0.012 to 0.086) 0.038 (-0.017 to 0.093) -0.041 (-0.093 to 0.011) 0.013 (-0.042 to 0.069)
Overall quality of evidence* Moderate Moderate Moderate Moderate Moderate
Keys: CI= confidence interval.
Conclusion
Benefits
Compared to placebo, Ginkgo biloba extract is not significantly more effective than placebo in preventing cognitive decline in memory, attention, visuospatial abilities, language and executive functions. For Outcome 1 – 5, 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
No significant adverse events were reported.
Link to Original Article
https://www.ncbi.nlm.nih.gov/pubmed/20040554
The synopsis is based on the following article:
Snitz BE, O'Meara ES, Carlson MC, Arnold AM, Ives DG, Rapp SR, et al. Ginkgo biloba for preventing cognitive decline in older adults: a randomized trial. JAMA. 2009 Dec 23;302(24):2663-70.


* 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.