At the University of Surrey in England, researchers found that a Ginkgo biloba extract could improve mood and activity levels of independent seniors.
Participants first underwent a four-month treatment with either ginkgo extract or a placebo capsule. Then in a second six-month trial, 1,570 volunteers continued treatment in one of four groups: some who received ginkgo in both trial periods, some who received ginkgo only in the first trial but not the second, some who did not receive ginkgo in the first trial but did in the second, and some who did not receive any treatment.
At the end of the second trial, a written self-assessment by the participants revealed significant differences between the groups, especially for mood and alertness. They found that ginkgo vastly improved mood and activity levels but that these improvements diminished when treatment stopped. They also found that the extent of these benefits to mood and everyday living was directly related to the duration of treatment.
Source: Phytother Res. 2004 Jul;18(7):531-7