Ginkgo for memory enhancement: a randomized controlled trial.

CONTEXT Several over-the-counter treatments are marketed as having the ability to improve memory, attention, and related cognitive functions in as little as 4 weeks. These claims, however, are generally not supported by well-controlled clinical studies. OBJECTIVE To evaluate whether ginkgo, an over-the-counter agent marketed as enhancing memory, improves memory in elderly adults as measured by objective neuropsychological tests and subjective ratings. DESIGN Six-week randomized, double-blind, placebo-controlled, parallel-group trial. SETTING AND PARTICIPANTS Community-dwelling volunteer men (n = 98) and women (n = 132) older than 60 years with Mini-Mental State Examination scores greater than 26 and in generally good health were recruited by a US academic center via newspaper advertisements and enrolled over a 26-month period from July 1996 to September 1998. INTERVENTION Participants were randomly assigned to receive ginkgo, 40 mg 3 times per day (n = 115), or matching placebo (n = 115). MAIN OUTCOME MEASURES Standardized neuropsychological tests of verbal and nonverbal learning and memory, attention and concentration, naming and expressive language, participant self-report on a memory questionnaire, and caregiver clinical global impression of change as completed by a companion. RESULTS Two hundred three participants (88%) completed the protocol. Analysis of the modified intent-to-treat population (all 219 participants returning for evaluation) indicated that there were no significant differences between treatment groups on any outcome measure. Analysis of the fully evaluable population (the 203 who complied with treatment and returned for evaluation) also indicated no significant differences for any outcome measure. CONCLUSIONS The results of this 6-week study indicate that ginkgo did not facilitate performance on standard neuropsychological tests of learning, memory, attention, and concentration or naming and verbal fluency in elderly adults without cognitive impairment. The ginkgo group also did not differ from the control group in terms of self-reported memory function or global rating by spouses, friends, and relatives. These data suggest that when taken following the manufacturer's instructions, ginkgo provides no measurable benefit in memory or related cognitive function to adults with healthy cognitive function.