Herb Research Foundation

JAMA study announces positive results in Alzheimer disease with Ginkgo extract

October 22, 1997. Results of a multicenter study published in the most recent issue of the Journal of the American Medical Association (JAMA) indicate that Ginkgo biloba extract can be of significant benefit in the treatment of dementia associated with Alzheimer disease and multi-infarct dementia (LeBars PL, Katz MM, Berman N, et al. A placebo-controlled, double-blind, randomized trial of an extract of Ginkgo biloba for dementia. JAMA 1997;278:1327-1332.). The authors asserted that the improvement seen in patients with Alzheimer could be equated with "a six-month delay in the progression of the disease." These results are particularly promising in light of the fact that no satisfactory treatments currently exist for the management of this common and devastating condition.

The placebo-controlled, double-blind study was designed to investigate the effects of standardized Ginkgo extract in 309 patients with mild-to-severe dementia associated with either Alzheimer disease or multi-infarct dementia. Patients were randomized to receive 52 weeks of treatment with placebo or Ginkgo extract at a dose of 40 mg three times a day, a total daily dose of 120 mg. At 52 weeks, 202 patients were included in the endpoint analysis, which was based on standard tests of cognitive impairment, daily living and social behavior, and general psychopathology.

The researchers reported that 27% of patients who received 26 or more weeks of treatment with Ginkgo extract experienced at least a four-point improvement on the 70-point Alzheimer Disease Assessment Scale-Cognitive subscale (ADAS-Cog), compared to 14% in the placebo group. Daily living and social behavior were deemed improved in 37% of Ginkgo patients, compared to 23% of those taking placebo, as measured by the Geriatric Evaluation by Relative's Rating Instrument (GERRI). In contrast, the GERRI showed that 40% of patients taking placebo experienced a worsening of their condition, while worsening was seen in only 19% of those taking Ginkgo.

The authors concluded that "EGb appears to stabilize and, in an additional 20 percent of cases (vs. placebo), improves the patient's functioning for periods of six months to one year. Regarding its safety, adverse events associated with EGb were no different from those associated with placebo."

The Ginkgo preparation used in the study (EGb 761) is a concentrated leaf extract standardized to 24% ginkgo flavone glycosides and 6% terpenelactones, the same extract widely used in Europe for the treatment of cognitive disorders and other conditions. This extract, manufactured by Murdock Madaus Schwabe, Inc. in Germany, is currently available in the United States under the trade names Ginkgold® (from Nature's Way Products, Inc.) and Ginkoba™ (from Pharmaton Natural Health Products).

Similar encouraging results with Ginkgo were recently reported in the journal Phytomedicine (Kanowski S, Herrmann WM, Stephan K, et al. Proof of efficacy of the Ginkgo biloba special extract EGb 761 in outpatients suffering from mild to moderate primary degenerative dementia of the Alzheimer type or multi-infarct dementia. Phytomed 1997;4(1):3-13.). This double-blind, placebo-controlled, randomized study investigated the effects of Ginkgo extract in 156 patients with either Alzheimer disease or multi-infarct dementia. A responder rate of 28% for multiple therapeutic effects (p<0.01) was observed in patients taking Ginkgo extract, as compared to 10% in the placebo group. A separate analysis of the two different diagnostic subgroups (Alzheimer or multi-infarct dementia) showed that the differences in improvements between Ginkgo and placebo after 24 weeks were consistently slightly higher in patients with Alzheimer disease. The researchers reported that the Ginkgo extract was well tolerated.