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Study Finds Ginkgo Ineffective for Memory Enhancement

Kate Traynor

A new study has found that a popular Ginkgo biloba product is no better than placebo for improving memory in older adults with normal mental functioning.

Six weeks of daily treatment with three 40-mg Ginkoba tablets did not change the learning and memory of a group of older adults any more than did a placebo taken by similar participants. The 230 adults, age 60 or older, who volunteered for the study were randomly assigned to receive the ginkgo product, by Boehringer Ingelheim Pharmaceuticals, or a similar-looking placebo. Before starting therapy and at the end of the study, each participant underwent a battery of standardized neuropsychological tests to assess verbal and nonverbal learning and memory.

The test results revealed no differences between the placebo and ginkgo groups for any of the 15 main outcomes studied. Likewise, no differences were found between the placebo and ginkgo groups in the subjective tests that evaluated whether a friend or relative of the study participant saw improvements in that person's memory.

The study results appeared in the Aug. 21 Journal of the American Medical Association (JAMA).

According to the report, advertisements for Ginkoba imply that the product enhances memory in people with or without cognitive impairment. For the current study, the research team used the dosage recommended in the product's labeling—40 mg of ginkgo three times a day, taken with food. Only adults without cognitive impairment were eligible for the study.

David Morrison, director of scientific affairs for Pharmaton Natural Health Products, which distributes Ginkoba, said that the results of the recently published study should be judged against the body of evidence supporting the effectiveness of ginkgo for memory enhancement.

"There've been hundreds of studies on Ginkgo biloba that in part look at cognitive function, and most have been positive," Morrison said.

The JAMA article acknowledged the existence of studies claiming that ginkgo improves memory and cognition, but the report's authors found shortcomings in several of these studies. For example, some studies "either report cognitive improvement in only 1 of many memory tests administered or report cognitive enhancement in cognitively impaired...patients."

Morrison noted that a study published in the August issue of Human Psychopharmacology: Clinical and Experimental evaluated 262 patients similar to those in the JAMA article and found that ginkgo did improve cognitive functioning.

In the placebo-controlled study reported in Human Psychopharmacology, a German ginkgo product was found to have improved the participants' memory in two portions of one neuropsychological test. The authors also reported a possible benefit in a third test of memory. None of the tests administered in this study were identical to those used in the investigation reported in JAMA.

Funding for the study of the German product was provided by its manufacturer and distributor. The research team responsible for the JAMA article obtained funding from the National Institute on Aging and two private research foundations.