Studies of Ginkgo Biloba for Memory Disorders
Nearly all the early studies that evaluated ginkgo biloba as a treatment for dementia came from Europe, and most did not employ rigorous research methodology. Then a North American consortium published a study in the Journal of the American Medical Association, utilizing EGb 761, an extract of ginkgo biloba marketed by a German company that provided the financial support for the experiment.
In that study, of the 309 patients with dementia who were randomized to receive EGb 761 or placebo, only 78 patients on EGb and 59 patients on placebo were able to complete the one-year study. The EGb 761 study’s results: even though the clinicians found no difference in their global impression between patients on ginkgo and placebo, patients on ginkgo showed significantly less decline on both a standard cognitive test and a forty-nine-item rating instrument completed by the caregiver (usually a family member). The test scores indicated that over the one-year study’s duration, the ginkgo group held its own, with no cognitive deterioration. In contrast, the placebo group worsened appreciably. The magnitude of the effect was small (2 to 3 percent advantage for ginkgo over placebo on a cognitive test), which is probably why the clinicians’ global impression showed no difference between the ginkgo and placebo groups. These findings are consistent with an earlier, less rigorous, study of 222 outpatients with dementia that showed 23 percent of patients improving on ginkgo biloba compared to 10 percent on placebo.
Side Effects of Ginkgo
In the EGb 761 study, other than a slight increase in stomach complaints, ginkgo’s side-effect profile was essentially identical to placebo. But as with every medication, alternative or otherwise, ginkgo is not totally devoid of side effects. It has anticoagulant (anticlotting) properties that increase the risk of bleeding in the presence of other anticoagulant medications, particularly warfarin (Coumadin), which is commonly prescribed for people at high risk for heart attack or stroke. A few such cases of complications due to excessive bleeding have been reported in the medical literature.
Promemory Actions of Ginkgo
Leaf extracts improve the ability of mice to remember newly learned behavior.
In animal studies, enhances recovery from injury to the frontal lobes.
In animal studies, acts against the memory deficits associated with aging.
In a few clinical studies, slows memory decline in dementia.
In healthy young adults, speeds up reaction time in stimulus-response tests, improving alertness.
Anticoagulant properties may protect against stroke (and hence indirectly against memory loss).
Antioxidant effects may protect directly against memory loss.
Ginkgo Improves Attention and Alertness
I have discovered that a surprisingly large number of people with mild memory deficits are taking ginkgo biloba. I have not yet seen a dramatic turnaround in any single individual, but some people do seem to become a little more alert. This may partly explain the results in clinical trials with ginkgo biloba, where the caregiver tends to report greater overall benefit than the clinician, who is focusing only on the memory deficit. Unfortunately, the studies with ginkgo have not used sophisticated neuropsychological testing to systematically evaluate the possibility that it leads to improved attention and greater alertness, rather than having a direct effect on memory. These activating effects may partly account for its promemory action: people who are alert and pay close attention tend to perform better on neuropsychological tests, including tests of memory.
Taken From: The Memory Program How to Prevent Memory Loss
and Enhance Memory Power
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