Numerous studies exist on the efficacy of the ginkgo biloba extract EGb761® in dementia. However, according to Prof. Dr. med. Dipl.-Psych. Ralf Ihl from the University of Düsseldorf, they differ in quality. Therefore, at the 28th Swiss Annual Conference on Phytotherapy in Baden, he presented four methodologically good studies that verified the effectiveness of this preparation.
Three of the studies presented [1–3] were placebo-controlled, randomized, and double-blind (RCTs). There were no methodological weaknesses that could have influenced the results. A fourth study [4] made a methodologically good comparison, albeit without placebo control and with a relatively low number of cases. “All studies meet the criteria of both the World Federation of Biological Psychiatric Societies (WFSBP, 2011) and the German Institute for Efficacy and Quality in Health Care (IQWIG),” said Prof. Dr. med. Dipl.-Psych. Ralf Ihl of the University of Düsseldorf.
Results of the studies presented
The three RCTs demonstrated significant superiority of EGb761® over placebo. The common target parameter was the so-called Syndrome Short Test (SKT), a short test for attention and concentration, which sometimes involves naming, remembering and sorting objects.
The first study [1] examined 400 outpatients aged more than 50 years with dementia (Alzheimer’s disease or vascular, neuropsychiatric symptoms). The therapy group received a daily dose of EGb761® 240 mg/d over a period of 22 weeks. Outcome was a mean -3.2 point improvement in SKT under EGb761® and a mean worsening of +1.3 points under placebo (p<0.001). Ginkgo extract was also significantly superior in all secondary endpoints, such as the “Neuropsychiatric Inventory” (NPI) or the “activities-of-daily-living” scale. There were no more frequent side effects than with placebo.
The second and third studies GOTADAY and GOT-IT! [2, 3] had been performed as sister studies with the same design. Patients with mild to moderate dementia (Alzheimer’s dementia, vascular dementia, or a combination of both) were studied. The therapy group received EGb761® 240 mg/d for a period of 24 weeks. The target parameter was not only the SKT but also the NPI.
GOTADAY showed an SKT improvement of -1.4 points and an NPI improvement of -3.2 points vs. placebo (n=202), +0.3 on the SKT score and no change in the NPI under the extract (n=202). Both changes were significant (p<0.001). Again, ginkgo extract also outperformed placebo in all secondary end points (e.g., “ADCS Clinical Global Impression of Change” [ADCS-CGIC], “Verbal Fluency” test, “activities-of-daily-living” scale [ADL-IS], “DEMQOL-Proxy quality-of-life” scale), and side effects were the same in both groups.
GOT-IT! showed an SKT improvement of -2.2 points and an NPI improvement of -4.6 points vs. placebo (n=202), -0.3 on the SKT score and -2.1 in the NPI, under the extract (n=200). Both changes were significant (p<0.001). Again, ginkgo extract also outperformed placebo in almost all secondary endpoints (ADCS-CGIC, “verbal fluency” test, ADL-IS, “DEMQOL-proxy quality-of-life” scale, and an 11-point tinnitus scale), and side effects were the same in both groups.
In the fourth study, EGb761® monotherapy was compared with donepezil monotherapy and with the combination of both substances. No significant differences in efficacy were found across all three groups.
None of the four studies found an increased rate of adverse events or side effects.
Safety is good
“Since the start of marketing, more than 20 billion daily doses (120 mg) of EGb761® have been manufactured, 850 million of them in 2009. Based on the sales figures and spontaneous reports of possible adverse drug reactions (ADRs), one can make the equation that among 5,000 patients taking the extract continuously over ten years, only one of them will experience an ADR once,” Prof. Ihl concluded.
Source: “Ginkgo Biloba – Results and Methodological Assessment of Clinical Studies on Dementia Treatment”, 28th Swiss Annual Conference on Phytotherapy, November 21, 2013, Baden.
HAUSARZT PRAXIS 2014; 9(1): 52-54
