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February 5, 2003

Ginkgo and Memory

JAMA. 2003;289(5):546. doi:10.1001/jama.289.5.546-a

In Reply: Several of these letters suggest that we did not cite studies that provided positive findings for ginkgo. We believe that these studies do not meet the rigor of the US Food and Drug Administration (FDA) guidelines.1 These standards include randomized, double-blind, placebo-controlled studies with outcome measures that demonstrate both statistical differences on objective cognitive tests and global measures to ensure that the statistical differences have tangible effects in day-to-day activities. Both Dr Nathan et al and Dr Arnold cite the study by Mix and Crews.2 Although this study did use a randomized, double-blind, placebo-controlled design, it reported the results of 13 neuropsychological tests (or subtests) of which only 3 were statistically significant. We question whether these inconsistent results constitute a truly positive study. This study also did not include a global measure, as required for FDA studies. Arnold and Nathan et al cite other articles that they claim support the efficacy of ginkgo.3,4 As in the case of the work by Mix and Crews,2 these articles report benefit in only a small fraction of cognitive tests and none include a global measure of clinical importance. A recent review of these and other articles concluded that there were no rigorously conducted studies that provide any evidence that ginkgo improves memory.5

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