The study, published in Lancet Neurology, included 2,854 people over 70 who told their doctor they were having memory problems. About half of them were assigned to take 120 mg of ginkgo twice daily and the other half were assigned to take a placebo. They were monitored for changes in memory and cognitive function as well as new diagnoses of dementia and probable Alzheimer’s disease for five years.
Overall, there was no statistically significant difference in the incidence of Alzheimer’s disease between people in the ginkgo and placebo groups.
However, results were more mixed when the researchers looked at the results across different subgroups within the participants. For example, ginkgo appeared to reduce the risk of developing Alzheimer’s disease in men and in alcohol consumers by more than half when these groups were considered separately. And when only people who used ginkgo or placebo for four years or more were considered, ginkgo appeared to have a protective effect.
The study authors note that, "Conclusions from this trial were restricted by the lower than expected incidence of Alzheimer’s disease. Further studies about long-term exposure to standardised ginkgo biloba (sic) extract might be warranted."
It is hard to pool data from multiple trials and reach a sound conclusion, and since other research has shown protective effects against Alzheimer's Disease before, this new study, with its primary finding, is hard to place within the body of evidence.The research on ginkgo is in agreement about its safety: for most people, taking ginkgo poses no risks. Here are some other safe measures to take to prevent memory loss and dementia:
(Lancet Neurology 2012; http://dx.doi.org/10.1016/S1474-4422(12)70206-5)