Ginkgo biloba has failed — again — to live up to its reputation for boosting memory and brain function. Just over a year after a study showed that the herb doesn't prevent dementia and Alzheimer's disease, a new study from the same team of researchers has found no evidence that ginkgo reduces the normal cognitive decline that comes with aging.

In the new study, the largest of its kind to date, DeKosky and his colleagues followed more than 3,000 people between the ages of 72 and 96 for an average of six years. Half of the participants took two 120-milligram capsules of ginkgo a day during the study period, and the other half took a placebo. The people who took ginkgo showed no differences in attention, memory, and other cognitive measures compared to those who took the placebo, according to the study, which was published in this week's Journal of the American Medical Association.