Ginkgo biloba did not slow the decline of mental function in seniors, according to a new study in The Journal of the American Medical Association.

“We found that there was no effect of the ginkgo biloba on these very slow but clearly detectable changes in thinking function in late life,” said Steven DeKosky, MD, dean of the University of Virginia School of Medicine and coauthor of the new ginkgo study, in The JAMA Report.

The researchers found that, compared with placebo, ginkgo (120 mg twice daily) did not result in less cognitive decline in the 3,069 adults aged 72 to 96 years participating in the randomized, double-blind, placebo-controlled clinical trial held between 2000 and 2008.

According to Mark Blumenthal, founder and executive director of the Austin, Texas-based American Botanical Council, the new JAMA study is one of the largest and longest ginkgo studies to date. He applauded researchers for using what he considers the correct ginkgo extract (EGb 761) and the proper dosage amount. However, “there are many significant limitations of this study,” Blumenthal said. He cited the following flaws:

* The data were drawn from a previous clinical trial, which was not designed to determine the decline in cognition. The original study, published in 2008, was on prevention of dementia.

* About 40 percent of the subjects dropped out over the 6-year duration of the trial. The study included the dropouts for which no final data are available.

* Certain cognitive parameters were not monitored until several years after the trial began.

* The age of the subjects was quite advanced, at an average of 79 years at the beginning of the trial. It is unknown whether a younger group of ginkgo users would have been more responsive.

“The bottom line: This is not the definitive trial on ginkgo,” said Blumenthal.

“The results of this new trial must be viewed in proper perspective,” Blumenthal added in an ABC press release. “There is a vast body of pharmacological and clinical research supporting numerous health benefits for ginkgo extracts, particularly for improving various symptoms and conditions associated with declining cognitive performance and poor circulation.” Blumenthal also emphasized that the new trial showed the overall safety of ginkgo.