Effects of Ginkgo biloba on dementia: An overview of systematic reviews

Objective: To assess the cumulative evidence on the efficacy and effectiveness of Ginkgo biloba extract (GbE) in the treatment of dementia. Design: Overview of systematic reviews. Methods: PubMed/MEDLINE, EMBASE, Cochrane, and Google Scholar were searched in June 2016. Systematic reviews (SRs) of randomized controlled trials (RCTs) evaluating the effects of GbE on different outcomes in people with dementia or cognitive impairment were included. Methodological quality of the included SRs was assessed using the AMSTAR tool. The quality of evidence of the primary studies was assessed using GRADE. Results: Twelve SRs with meta-analyses met the eligibility criteria. The quality of the evidence reported in these SRs varies ranging from low to moderate level. Overall, the available evidence suggests that GbE has potentially beneficial effects over placebo on cognitive performance, activities of daily living, and clinical global impression in the treatment of dementia at doses greater than 200 mg/day (usually 240 mg/day) administrated for 22 weeks or longer, and that GbE appears to be safe for human consumption. No sufficient evidence supports the favorable effects of GbE administrated for less than 22 weeks. The available evidence consistently indicates that a dose less than 200 mg/day of GbE may not be adequate to yield clinical relevant effects in the treatment of dementia. Conclusions: GbE has potentially beneficial effects for people with dementia when it is administered at doses greater than 200 mg/day for at least 5 months. Given the lower quality of the evidence, further rigorously designed, multicenter-based, large-scale RCTs are warranted.