reviewed by X. Li, Ph. D.
(credential)
As people get older, it is not uncommon to experience difficulties in learning and memory. Other related
symptoms may include impaired concentration, reduced alertness, decreased energy, tiredness, confusion,
dizziness, tinnitus, anxiety and decreased physical performance. While these symptons are
loosely termed age-associated memory impairment (AAMI) or age-related cognitive decline (ARCD) or
celebral insufficiency, it is often hard to draw a clear line in defining it as a disease
from the normal aging process. On the other side, when the symptons in celebral insufficiency are clearly
signs of disease, it may be hard to differ it from Alzheimer's disease or other forms of dementia.
It is thought that symptons of age-associated memory impairment are linked with decreased cerebral
circulation. Because experiments showed that ginkgo biloba may increase blood circulation to
the brain1, it is logical to test if ginkgo biloba extract may improve memory impairment in
patients with age-associated memory impairment.
Many clinical trials has been conducted to study the effect of the standardized ginkgo biloba extract
on celebral insufficiency. A critical review identified 40 such trials2.
Most of these trials included small patient numbers and had poor designs or descriptions of trials themselves.
Although their conclusions agreed on generally the positive role of ginkgo on memory impairment,
unfortunately, they did not hold up the strict standards such as required by FDA to support such claim.
Nevertheless, 8 out of 40 trials were found to be well performed and the quality of trials were
sufficient enough to make credible conclusions.
In these 8 trials, patients were typically given 120 to 160 mg ginkgo biloba extract daily for at least 4-6 weeks.
All 8 trials reported positive results and supported the conclusion that ginkgo biloba extracts reduce the symptons of
cerebral insufficiency to the extent that is clinically relevant2.
It is noteworthy that the role of ginkgo in improving age-associated memory impairment is consistent
with the role of ginkgo in stabilizing and improving dementia.
Reference
1. Maclennan KM, Darlington CL, Smith PF.The CNS effects of Ginkgo biloba extracts and ginkgolide B.
Prog Neurobiol. 2002 Jun;67(3):235-57.
2. Kleijnen J, Knipschild P. Ginkgo biloba for cerebral insufficiency. Br J Clin Pharmacol. 1992 Oct;34(4):352-8.
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