Paul R. Solomon of Williams College and his colleagues conducted a six-week, double-blind study of 230 healthy adults ages 60 and older, giving half of the subjects ginkgo and the other half placebo. Participants completed standardized tests of learning, memory, attention and concentration before, during and after the study period. The researchers also questioned the subjects themselves and their close friends and family about any perceived shifts in cognitive status. What they found was that ginkgo recipients fared no better on the tests than placebo recipients did. "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," they say.
Solomon and his collaborators acknowledge that higher doses of the supplement or longer periods of exposure might produce the desired effects. But they conclude that their results "suggest that when taken following the manufacturer's instructions, ginkgo provides no measurable health benefit in memory or related cognitive function to adults with healthy cognitive function."