Although the herb Ginkgo biloba is widely marketed and used to improve cognitive health in aging, adequate scientific evidence of its effect on long-term cognitive functioning has been lacking. In a recent study, NCCAM-funded researchers analyzed data from the Ginkgo Evaluation of Memory (GEM) study to determine ginkgo's effect on cognitive health in older adults.
The GEM study—the largest of its kind to date—was a randomized, double-blind, placebo-controlled clinical trial of 3,069 community-dwelling adults aged 72 to 96, conducted in multiple academic medical centers in the United States between 2000 and 2008. The median followup time was 6.1 years. Participants, who had normal cognition or mild cognitive impairment when they entered the study, received 120 mg of ginkgo or an identical-appearing placebo twice daily, and underwent a variety of cognitive tests over the course of the study.
Compared with placebo, ginkgo did not lessen cognitive decline. Researchers found no evidence of an effect on cognitive decline in general, or on memory, attention, visual-spatial construction, language, or executive functions. There were no differences by age, sex, race, education, or baseline cognitive status.
An earlier analysis of GEM data found that ginkgo was not effective in reducing the incidence of overall dementia and Alzheimer's dementia. The researchers noted that the GEM findings are consistent with those of previous smaller studies and with a 2009 Cochrane review of ginkgo for dementia and cognitive impairment.
Snitz BE, O'Meara ES, Carlson MC, et al. Ginkgo biloba for preventing cognitive decline in older adults: a randomized trial. Journal of the American Medical Association.; 302(24):2663–2670.2009
Birks J, Grimley Evans J. Ginkgo biloba for cognitive impairment and dementia. Cochrane Database of Systematic Reviews.; (1):CD003120.2009
DeKosky ST, Williamson JD, Fitzpatrick AL, et al. Ginkgo biloba for prevention of dementia. Journal of the American Medical Association.; 300(19):2253–2262.2008