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
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.
Six-week randomized, double-blind, placebo-controlled, parallel-group
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
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.
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.
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.