Abstract & Commentary
Synopsis: When taken at its recommended dose, ginkgo does not improve the memory of healthy elders.
Source: Solomon PR, et al. JAMA. 2002;288:835-840.
To evaluate the efficacy of ginkgo for memory enhancement, Solomon and colleagues from New England recruited healthy volunteers by way of newspaper advertisements that asked for volunteers for a study of memory improvement. To be included, the volunteer had to be living in the community, be older than age 60, be able to give informed consent, have a companion with whom they had regular contact, be willing to complete a questionnaire, and score greater than 26 on the Mini-Mental State Examination (MMSE). Subjects were excluded if they had a history of psychiatric or neurologic disease, a life-threatening illness within the last 5 years, or ingestion of an antidepressant or other psychoactive medication within the last 60 days. From July 1996 to September 1998, they screened 338 potential participants. After exclusion, 230 were randomized to ginkgo (Ginkoba®) 40 mg 3 times a day with meals (the manufacturer’s recommended dose) or to placebo. The randomization was double blinded. The subjects ranged in age from 60 to 82 years. The 2 groups were similar in age (about 69 years), gender (about 45% male), education (about 14 years), and MMSE score (just short of 29 out of 30). All were independent in instrumental activities of daily living. Immediately before starting the study, and again at 6 weeks, they took 14 standardized tests of learning, memory, attention and concentration, expressive language, and mental status along with a self-assessment of memory. Additionally, at the 6-week mark, the companion completed a global evaluation of the subject that provided "an overall impression of change in memory." Compliance with the study design was monitored by biweekly telephone calls and return of the drug envelopes at the end of the study. Analysis was by modified intention-to-treat (those who received at least 1 dose of ginkgo) and the fully evaluable population (those who completed the study and took all the drug). Both analyses failed to show a significant difference in any test between the study group and the control group. Both groups performed better at the 6-week evaluation than the initial one, which Solomon et al attribute to a practice effect.
Comment by Allan Wilke, MD
Ginkgo biloba (or Maidenhair tree) has been around forever, its roots (pun intended) in prehistoric times. I think that has something to do with its cachet; anything that could have survived unchanged since the Permian period must have something going for it! The word ginkgo is derived from its Chinese name yin kuo (silver fruit). It is a staple of Chinese medicine and has been used by millions for hundreds of years. With that kind of record, you would think that any benefit or hazard would be well known by now. The active ingredients are thought to be flavonoid glycosides and ginkgolides (a type of diterpines). It is a potent inhibitor of platelet activating factor and has antioxidant properties. Ginkgo is touted to treat a wide variety of ills, including acute mountain sickness,1 schizophrenia,2 female sexual dysfunction,3 intermittent claudication,4 dementia,5 ocular blood flow,6 equilibrium disorders,7 premenstrual syndrome,8 and Alzheimer disease.9 The aphorism, "if it seems too good to be true, then it probably is not," apparently applies to ginkgo’s ability to enhance memory in healthy, non-demented adults.
This study had limitations. Adverse effects were not monitored, although no one dropped out of the study because of adverse effects. In past reports, ginkgo has been regarded as benign with bleeding, mild gastrointestinal upset, dizziness, palpitations, allergic skin rashes, and headache being the most common complaints. There were no power calculations; a larger study might reveal a difference between the study and control groups. Perhaps this was not the right product, and there exists a more efficacious formulation. It will probably be argued that the length of treatment was too short or the dose was not high enough. However, the manufacturer recommends a dose of 120 mg/d and states that, "Our clinical research indicates that with at least 4 weeks of uninterrupted use of Ginkoba®, consumers can begin to enjoy its many benefits-including improvements in mental sharpness and focus." (This and other product statements can be found at www.ginkoba.com.)
What should you advise your patients who ask if they should purchase Ginkoba®? As with any decision, they should weigh the benefits and risks. Ginkgo has a number of potential benefits as mentioned above, although short-term memory enhancement does not appear to be one of them. My local Rite Aid Pharmacy sells a 72-tablet (24-day supply—curiously, a few days short of the recommended 4 weeks) for $18.99. A 4-week trial, assuming the bleeding, GI upset, headache, etc. are tolerable, seems innocuous enough and not terribly expensive. If your patient has any bleeding tendencies, including use of warfarin or aspirin, you should caution against its use, and, of course, use by a pregnant patient should be avoided.
Dr. Wilke, Assistant Professor of Family Medicine, Medical College of Ohio, Toledo, OH, is Associate Editor of Internal Medicine Alert.
References
1. Gertsch JH, et al. High Alt Med Biol. 2002;3:29-37.
2. Zhang XY, et al. J Clin Psychopharmacol. 2001;21: 85-88.
3. Waynberg J, et al. Adv Ther. 2000;17:255-262.
4. Pittler MH, et al. Am J Med. 2000;108:276-281.
5. Le Bars PL, et al. JAMA. 1997;278:1327-1332.
6. Chung HS, et al. J Ocul Pharmacol Ther. 1999;15(3): 233-240.
7. Cesarani A, et al. Adv Ther. 1998;15:291-304.
8. Tamborini A, et al. Rev Fr Gynecol Obstet. 1993;88: 447-457.
9. Oken BS, et al. Arch Neurol. 1998;55:1409-1415.
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