A meta-analysis on the effects of Ginkgo biloba extract (EGB 761) on memory recall among healthy individuals with no signs of cognitive impairment.

BACKGROUND: Ginkgo biloba extract (EGb 761, tanakan, Ginkgold, Ginkoba, Ginkai) is one of the most widely utilized plant-based medicinal product. The active ingredients in the commercial preparations of Ginkgo biloba contains varying factions of ginkgo flavonoid glycosides, terpene lactones, and ginkgolic acids. The pharmacologic actions of ginkgo biloba are theorized to be due to a combination of several of its effects such as vasodilatory, antioxidant property, neurotransmitter modulation and inhibition of platelet activating factors. Most trials involved participants either at risk for developing dementia or already suffering from mild to severe cognitive dysfunction. Considering that most consumers are healthy individuals with no cognitive dysfunction, it is pragmatic that a search for evidence supporting its usage as a memory enhancer for normal healthy individuals be conducted.

OBJECTIVE: Assess the efficacy of Ginkgo biloba in enhancing cognitive function namely short-term and delayed memory recall, learning and attention among healthy individuals with no signs of cognitive dysfunction.

SEARCH STRATEGY: Key Terms: Ginkgo biloba, Tanakan, Tebonin, Rokan, Kaveri, Ginkgold, Ginkoba, Ginkai, EGb-761, EGb761, EGb 761, memory recall, cognitive enhancement, learning, attention, normal individuals, normal volunteers, normal subjects, healthy individuals, healthy volunteers, healthy subjects.

SELECTION CRITERIA: Randomized, double-blind, placebo-controlled clinical trials using Gingko biloba as an intervention for enhancement of cognitive function among healthy adults with no sign of cognitive dysfunction.

DATA COLLECTION & ANALYSIS: Two reviewers independently reviewed the studies. Results were gathered from published and unpublished articles, journals and clinical trials. Studies were critically appraised with regards to methods of minimizing bias. A third reviewer independently reviewed the quality assessment done. All 5 studies included received a quality scale for meta-analysis overall score of not less than B.

RESULTS: In short-term and delayed memory recall, the use of Ginkgo biloba showed no significant difference with placebo (short-term memory: p = 0.72 95 % CI -0.90 to 0.66}; delayed memory: P = 0.50 (95% CI 0.05 to 0.89}; Overall effect in memory recall is not significant p = 0.07 {95 % CI -0.03 to Volt}. Likewise, there is no significant difference between the Ginkgo biloba group and placebo in enhancing learning (p = 0.43 {95% CI -0.53 to 0.36}). In evaluation of attention, there is statistical significance overall between Ginkgo biloba and placebo in improving attention (p= 0.0001; 95% CI of -3.26 to -1.49).

CONCLUSION: There is no statistical significance between the efficacy of Ginkgo biloba versus placebo in enhancing short-term and delayed memory recall, and learning among healthy individuals with no signs of cognitive dysfunction. However, in the test for the evaluation of improvement in attention (Digit Span), there is statistical significance (P=0.0001) favoring the use of Ginkgo biloba among healthy individuals with no cognitive dysfunction.