Ginkgo Extracts Show Promise|
Sean Henahan, Access Excellence
Washington, DC (October 22, 1997)- An extract of the plant Ginkgo
biloba, long used in Chinese medicine, appears to provide some benefit
for some patients with Alzheimer's disease, reported clinical
researchers at the American Medical Association's 16th Annual Science
Researchers from the New York Institute for Medical Research,
Tarrytown, N.Y., compared the effects of EGb 761, a particular extract
of Ginkgo biloba, and and placebo in a year-long, double-blind study of
309 demented patients with mild to moderately severe cognitive
impairment caused by Alzheimer disease, vascular dementia or a
combination of the two.
The results indicated that EGb had a measurable effect on cognitive
impairment and daily living and social behavior in patients with
dementia. Although the treatment effect could not be detected by the
clinician's global impression of change, it was demonstrated through
objective tests of cognitive performance and was strong enough to be
noticed by caregivers.
A little more than one quarter of patients treated for at least six
months with EGb achieved at least a four point improvement on the
commonly used 70 point Alzheimer Disease Assessment Scale-Cognitive
subscale, compared with 14 percent taking placebo. Another rating scale,
the Geriatric Evaluation by Relative's Rating Instrument (GERRI), showed
improvement in daily living and social behavior of 37 percent of the
patients taking EGb, compared with 23 percent taking placebo.
"Compared with the placebo group, the EGb group included twice as
many patients whose cognitive performance improved and half as many
whose social functioning worsened. In clinical terms, improvement on the
ADAS-Cog of four points may be equivalent to a six-month delay in the
progression of the disease. EGb appears to stabilize and, in an
additional 20 percent of cases (vs. placebo), improve the patient's
functioning for periods of six months to one year. Regarding its safety,
adverse events associated with EGb were no different from those
associated with placebo," reported Pierre L. LeBars, M.D., Ph.D.
"Although it has a reasonably modest effect, it could be meaningful
to caregivers. To have a plateau for six months and be able to interact
with the person when they're still at a relatively early stage is
something that many families would appreciate, I think," Marcelle
Morrison-Bogorad, an Alzheimer's disease researcher at the National
Institute on Aging at the National Institutes of Health, told the press.
Extracts from the Ginkgo biloba tree have long been used in China for
diseases associated with old age. The extract of Ginkgo biloba used in
this study, EGb 761, has recently been approved in Germany for the
treatment of dementia.
The researchers do not know how EGb exerts its neurological effects.
Ginkgo extracts contain antioxidants that may help to protect cells
against oxidative damage. Oxidative damage has been seen in the brain
cells of Alzheimer's patients. Ginkgo extracts also contains compounds
that act as vasodilators, increasing blood flow. They also contain
substances which exert strong anti-platelet effects.