Medicine for the Outdoors
Medicine for the Outdoors

Dr. Paul Auerbach is the world's leading outdoor health expert. His blog offers tips on outdoor safety and advice on how to handle wilderness emergencies.

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Gingko biloba for Prevention of Dementia

Some posts back, I wrote about the use of Gingko biloba for the prevention of acute mountain sickness (AMS). Now there appears an article in the Journal of the American Medical Association (JAMA) [2008;30(19):2253-2262] entitled, "Gingko biloba for prevention of dementia: a randomized controlled trial," authored by Steven T. DeKosky et al.

The authors note that G. biloba is widely used for its potential effects on memory and cognition. They further note that prior to their clinical trial, there was no adequate investigation from which G. biloba's effects could be determined. So, their objective was to determine the effectiveness of G. biloba versus a placebo in reducing the incidence of all-cause dementia and Alzheimer disease in elderly persons with normal cognition and in those with mild cognitive impairment. In a statistically valid number of individuals, using twice-daily doses of 120 mg extract of G. biloba versus placebo, they concluded that this treatment regimen was not effective in reducing either dementia or Alzheimer disease.

There are many reasons offered for why G. biloba might be effective as a drug, including possible reduction of oxidative stress that perhaps leads to dementia or cerebrovascular disease, reduction of amyloid aggregation, or other effect(s). However, based upon this study, it does not appear that there is a benefit to taking G. biloba.

What is the implication of this for the outdoor medicine community? I think it highlights how little we know about drugs, supplements, and natural products that are often recommended as remedies, cures, and preventive agents for a wide variety of environmental medical problems, such as high-altitude illness, allergic reactions, snakebite, insect bite, marine envenomations, and others. We are still relatively early in our understanding of the pathophysiology of issue such as acute mountain sickness. We are becoming confident that it reflects a degree of brain swelling, but how much and why? Is there a logical reason why ingesting G. biloba would be expected to hasten acclimatization, or prevent or reverse a fundamental or subtle pathophysiological process related to hypoxia and brain dysfunction? The strength of our empirical observations will in large part be determined by designing and implementing large, statistically valid investigations, such as these authors did for looking at G. biloba and its (failed) effect on the prevention of dementia. Granted, in extrapolating from dementia to AMS, we may be comparing apples and oranges, but I am still cautioned about placing too much reliance on G. biloba for the prevention of AMS until someone can show me why it makes sense that it should be effective.

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About the Author

Dr. Paul S. Auerbach is the world’s leading authority on wilderness medicine.