Popular Diet Suppliment, Gingko, Found to Be Ineffective in Preventing Alzheimer's

Ginkgo bilboa, a dietary supplement widely touted as a natural remedy for memory loss associated with aging or even to delay or prevent the development of Alzheimer's disease, has been shown to be no more effective than a placebo.

That's the verdict of Ginkgo Evaluation of Memory (GEM) clinical trial, which is published in the November 19, 2008 issue of the Journal of the American Medical Association (JAMA. 2008; 300(19):2253-2262).

In the GEM study a total of 2,587 volunteers aged 75 and older without evidence of Alzheimer's and 482 with documented mild cognitive impairment (such as loss of short-term memory or confusion regarding day and date) were enrolled in the study, which was conducted at five academic medical centers in the United States. The study groups were given either 120 milligrams of gingko bilboa twice a day or a placebo and reevaluated for the development of symptoms of cognitive impairment every six months.

The study group was followed for a mean period of 6.1 years. During that period a total 523 subjects were diagnosed with dementia, with 246 (16.1%) coming from the group taking a placebo and 277 (17.9%) in those taking gingko biloba. The rates of per-year cases of dementia did not differ significantly between the two groups, with 3.3 versus 2.9 cases per 100 person-years with gingko biloba versus a placebo. The rates of Alzheimer-type dementia were also similar, at 3.0 and 2.6 cases per 100 person-years with gingko biloba versus placebo, respectively.

Although not specifically addressed in the GEM study, there was also no indication that gingko biloba offered any protective effect regarding the development of cerebrovascular (brain and blood vessel) disease nor did it appear to reduce the incidence of stroke when compared with the placebo group.

In an accompanying editorial Lon S. Schneider, MD of the University of Southern California at Los Angeles pointed out that the GEM trial is by far the largest and longest clinical trial that "comprises the substantial bulk the non-industry-funded, placebo-controlled clinical database for gingko biloba extract..." and provides no evidence that gingko bilboa contributes to any meaningful risk reduction for either Alzheimer's or other, non-specific, dementias.

GEM was supported by the National Center for Complementary and Alternative Medicine; the Office of Dietary Supplements and National Institute on Aging; and the National Heart, Lung, and Blood Institute, all of which are parts of The National Institutes of Health.

Comment

The GEM study demonstrates two important facts concerning Alzheimer's disease and other types of less severe cognitive impairment.

The first, and most obvious, is that gingko bilboa has no delaying or preventive effects on either of the conditions mentioned above. As a consequence of this finding it would seem that those of greater than 75 years of age, the vast majority of whom are living on a fixed and usually limited income, would be better served by not spending that income on this product.

Secondly, it must be remembered that Alzheimer's and other dementias are an age-related phenomenon and thus represent the cumulative effect of a lifetime. It should then be equally obvious that the most effective prevention of these diseases is a lifetime of healthy living habits. There is more than enough evidence that a life-long practice of a eating a nutritious diet, exercise, and routine health checkups will do more to prevent health problems in later life than any other factor.

Until sufficient reputable medical evidence to the contrary is presented there is no benefit to your health, or the health of a family member, to be had from gingko bilboa when used as a prevention of Alzheimer's disease or age-related cognitive impairment.