Objectives: Few investigations have examined the effectiveness of Ginkgo biloba extract for enhancing cognitive abilities in individuals with no history of significant neurocognitive dysfunction. The purpose of this research was to examine the relatively short-term (i.e., 6 weeks) efficacy of Ginkgo biloba extract EGb 761 on the cognitive functioning of cognitively intact persons over the age of 55 years via a diverse battery of neuropsychologic tests and measures.
Participants: From the 48 cognitively intact participants between the ages of 55 and 86 years who initially enrolled in this study, 21 males and 19 females successfully completed the study's protocol and provided valid data sets.
Design: A 6-week, double-blind, fixed-dose, placebo-controlled, parallel-group experimental design was utilized. Participants were randomly assigned to either a Ginkgo biloba extract EGb 761 (180 mg/d) or placebo control group. To evaluate participants' cognitive and behavioral functioning, series of neuropsychological tests were administered to them prior to the initiation of the Ginkgo biloba extract/placebo therapy (i.e., pretreatment baseline) and again, just prior to the termination of the treatment regimen (i.e., after 6 weeks).
Results: Participants who received 180 mg of Ginkgo biloba extract EGb 761 daily for 6 weeks exhibited significantly more improvement on a task assessing speed of processing abilities (i.e., Stroop Color and Word Test color-naming task) by the end of treatment as compared to participants who received placebo. Trends favoring improved performances in the Ginkgo biloba group were also demonstrated in three of the four remaining tasks that involved a timed, speed of processing component, although they did not reach statistical significance. Furthermore, a significant relationship was found between the type of treatment (Ginkgo biloba extract or placebo) and participants' ratings of their overall abilities to remember. Specifically, more participants in the Ginkgo biloba extract group rated their overall abilities to remember by the end of treatment as "improved," as compared to the placebo group. In contrast, no significant differences were found between the Ginkgo biloba and placebo groups by treatment end on any of the four objective memory measures.
Conclusions: Taken together, the findings from standardized neuropsychologic assessment and a subjective, self-report questionnaire suggested that relatively short-term (i.e., 6 weeks) utilization of Ginkgo biloba extract EGb 761 may prove efficacious in enhancing certain neurocognitive functions/processes of cognitively intact older adults.