Study shows ginkgo not effective for memory improvement
Manufacturers of ginkgo products claim this herb “enhances mental focus and improves memory and concentration.” German doctors regularly prescribe the popular herb for Alzheimer's disease and other severe forms of memory and mental function decline. Some research even suggests that ginkgo may help offset ordinary age-related memory loss. In contrast, research published in the August 21, 2002 Journal of the American Medical Association found that ginkgo did not improve memory or concentration in healthy older adults.
About the study
Researchers at Williams College in Amherst, Massachusetts studied 230 community-dwelling men and women between the ages of 60 and 82. In recruiting participants, the researchers screened out people with cognitive impairment by giving potential participants the Mini-Mental State Exam; those with scores below the normal range were excluded from the study. People were also excluded if they had a history of psychiatric or neurologic disorders, had a life-threatening illness in the past five years, or had taken antidepressants or other psychoactive drugs in the past 60 days.
Participants were randomly assigned to take either 40 mg of ginkgo (Ginkoba brand) or a matching placebo (inactive) pill three times daily for six weeks. One day before starting treatment, participants underwent tests of memory and concentration, which included tasks such as:
- Learning a 16-item shopping list and then recalling the items
- Recalling concepts from paragraphs immediately after reading them and then again 30 minutes later
- Drawing designs immediately after seeing them and again after a 30-minute delay
- Repeating increasingly long strings of numbers after hearing them
- Reciting strings of numbers and letters after hearing them
- Naming members of a particular category (for example, animals) over a one-minute period
- Rating how often they experienced certain memory lapses
The same tests were administered again after six weeks. Also at six weeks, a spouse, relative, or friend rated how the individual participant’s memory changed over the study period.
Researchers compared the test scores and memory ratings of the ginkgo group with those of the placebo group.
Both groups performed better on the memory/concentration tests after six weeks. However, there were no differences in tests scores or participant memory ratings between the ginkgo and placebo groups. In addition, the relative/friend ratings of memory improvement were similar in both groups. These findings suggest that the modest improvement in both groups was due to participants knowing how the tests worked the second time around.
Although these results suggest that ginkgo does not enhance memory and concentration, this study has its limitations. The doses used in this study matched the manufacturer’s instructions, but it’s possible that higher doses would produce beneficial effects. In addition, the researchers did not analyze the contents or purity of the ginkgo. However, according to the manufacturer, the product is processed under strict guidelines and the contents are ensured through extensive quality control. Finally, because the participants were generally healthy and free of mental function problems, it’s still not clear whether ginkgo might improve memory and concentration in people with existing problems in these areas.
How does this affect you?
These findings suggest that ginkgo does not improve memory or concentration in healthy older adults with no apparent mental function problems. This research does not, however, address ginkgo’s effectiveness in treating Alzheimer's disease and other severe forms of memory and mental function decline. Several double-blind studies have reported that ginkgo produces beneficial effects on memory and concentration, but these effects have not been consistent.
Will ginkgo improve your memory and concentration? The jury is still out, but the findings of this study suggest that people without mental function problems probably won’t benefit from taking ginkgo.
Solomon PR, Adams F, Silver A, Zimmer J, DeVeaux R. Ginkgo for memory enhancement: A randomized controlled trial. JAMA . 2002;288:835-840.
Last reviewed Aug 21, 2002 by ]]>Elizabeth S. Smoots, MD]]>
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