Ginkgo biloba for the improvement of cognitive performance in multiple sclerosis:: a randomized, placebo-controlled trial

Objectives To determine if Ginkgo biloba (GB) improves the cognitive performance of subjects with multiple sclerosis (MS). Methods Randomized, double-blind, placebo-controlled trial of GB, 120 mg twice a day or placebo for 12 weeks. The primary outcomes were: the long delay free recall from the California Verbal Learning Test-II; the Paced Auditory Serial Addition Test; the Controlled Oral Word Association Test; the Symbol Digit Modalities Test; Useful Field of View Test; and the color-word interference condition from the Stroop Color and Word Test. Results On completion, the GB group (n =20) was 4.5 seconds (95% confidence interval (Cl) (7.6, 0.9), P =0.015) faster than the placebo group (n = 18) on the color-word interference condition of the Stroop test. Subjects who were more impaired at baseline experienced more improvement with GB (treatment*baseline interaction, F=8.10, P=0.008). We found no differences on the other neuropsychological tests. Subjects on GB reported fewer cognitive difficulties in the Retrospective Memory Scale of the Perceived Deficits Questionnaire than subjects on placebo (1.5 points, 95% CI (2.6, 0.3), P=0.016). No serious drug related side-effects occurred and GB did not alter platelet function assays. Conclusion Overall, GB did not show a statistically significant improvement in cognitive function. A treatment effect trend, limited to the Stroop test, suggests that GB may have an effect on cognitive domains assessed by this test, such as susceptibility to interference and mental flexibility.