Researchers in a brain study reviewed six clinical trials of people with dementia who took ginkgo biloba or a placebo for at least six months. Everyone took a 30-minute test that included mental tasks such as planning, setting goals and remembering. By the end of the study, the ginkgo group had raised its test scores significantly while the placebo group had not changed. Compared to placebo, those who took ginkgo were much better able to plan, set goals, prioritize tasks, remember and were more aware of place and time.