Dodge HH et al. (2008) A randomized placebo-controlled trial of ginkgo biloba for the prevention of cognitive decline. Neurology [doi:10.1212/01.wnl.0000303814.13509.db]

There is some evidence to indicate that Ginkgo biloba extract (GBE)—a widely used alternative medicine—might have a beneficial effect on brain aging mechanisms. In a study of this agent in cognitively normal individuals aged 85 years or older, however, Dodge et al. have found no clear effect of GBE on the progression of cognitive decline but have noted an increased risk of stroke in those receiving this extract.

The researchers randomized 118 individuals to either daily 240 mg GBE (n = 60) or placebo (n = 58). Cognitive status was assessed every 6 months, with the primary outcome measure being mild cognitive decline. During follow-up (mean duration 3.15 years), 14 individuals in the placebo group and 7 in the GBE group exhibited mild cognitive decline. Kaplan–Meier analysis did not reveal a significant protective effect of GBE on memory. However, a secondary analysis controlled for baseline medication adherence demonstrated that people who reliably took the supplement had an approximately 70% lower risk of mild cognitive decline than those receiving placebo (hazard ratio 0.33, 95% CI 0.12–0.89; P <0.05).

Although the overall incidence of adverse events was similar in the two groups, a greater number of people in the GBE group than in the placebo group had a stroke or transient ischemic attack (P = 0.01, uncorrected for multiple comparisons). GBE has been reported to cause bleeding-related complications, but the strokes reported in this study were almost all nonhemorrhagic.

The authors conclude that further larger studies of GBE as a primary prevention agent for dementia are warranted.