An extract of the dried leaves of the Ginkgo biloba tree is used in Europe to alleviate symptoms associated with a range of cognitive problems and has recently been approved in Germany for the treatment of dementia. Ginkgo is thought to have antioxidant properties, although its exact mechanism of action is unclear. Le Bars and colleagues conducted a randomized, double-blind, placebo-controlled trial to test the efficacy of ginkgo in the management of patients with Alzheimer's disease and multi-infarct dementia.
Patients were included in the study if they were at least 45 years old and had been diagnosed with Alzheimer's disease or multi-infarct dementia, and had a Mini-Mental State Examination score of nine to 26 and a Global Deterioration Scale score of three to six. Patients with significant medical problems such as type 1 diabetes or cardiac disease were excluded from the study. Changes in medication regimens were not allowed during the study period. Data from 202 patients were compared for the one-year study. Each patient underwent a 14-day, single-blind run-in period. Patients were reevaluated at four, 12, 26, 39 and 52 weeks. Extensive medical, neurologic and psychiatric examinations were performed at baseline and at the end of the study. Patients were randomized to receive either placebo or 40 mg of ginkgo three times daily before meals. The three primary outcomes assessed changes in the following areas: cognitive impairment, daily living and social behavior, and general psychopathology.
A total of 166 patients were randomized to the ginkgo treatment group, and 161 were randomized to the placebo group. Patients receiving ginkgo demonstrated no worsening of their cognitive impairment at end point, compared with a 1.5 point worsening (based on the Alzheimer's Disease Assessment Scale—Cognitive subscale [ADAS-Cog]) in the placebo group. The Geriatric Evaluation by Relative's Rating Instrument (GERRI), a caregiver-rated assessment, showed mild improvement in the treatment group and significant worsening in the placebo group. At the halfway point of the study, patients in the ginkgo group showed a slight improvement on both the ADAS-Cog and GERRI scales, whereas the placebo group showed significant worsening. Adverse events were not significantly different between the treatment and placebo groups, and were considered to be mild to moderate in intensity.
The authors conclude that treatment with extract of Ginkgo biloba is safe for up to one year in patients with dementia and can improve cognitive performance and functioning. The improvement was significant enough to be identified by the patient's caregiver.