Jinzhou Tian*, Jing Shi, Xuekai Zhang and Yongyan Wang
Corresponding author: Jinzhou Tian firstname.lastname@example.org
Alzheimer's Research & Therapy 2010, 2:30 doi:10.1186/alzrt54
(2010-12-07 14:04) Medical University of Vienna
Tian et al. arrive at a negative conclusion with regard to Ginkgo biloba for the treatment
of Alzheimer's disease by relying on a Cochrane Review  and a study that did not
really address the question they were trying to answer . Unfortunately, the cited
Cochrane review is flawed in that it lumps together studies using different Ginkgo
products that can by no means be considered bioequivalent as well as studies in patients
with different diseases or ailments (merely subjective memory complaints, mild cognitive
decline, overt dementia). Obviously, it does not make sense to estimate a common effect
size for 0.57 mg flavone glycosides and 0.97 mg ginkgolides per day in subjective
cognitive complaints  and 58.8 mg flavone glycosides and 14.4 mg terpene lactones
per day in dementia , as done in Birks' analysis no. 1.15. Furthermore, it is not
true that three of the four most recent trials showed no difference between Ginkgo
and placebo: the trials by Napryeyenko  and Mazza  showed significant superiority
of Ginkgo biloba extract over placebo. The DIGGER trial  was an attempt to address
two questions at the same time and was seriously underpowered after repeated downward
calculation of the sample size due to recruitment problems.
Finally, Snitz et al.  reported on a prevention trial in elderly people who were
cognitively healthy or had MCI. It is not possible to draw any conclusions with respect
to efficacy of Ginkgo biloba extract in the treatment of Alzheimer's disease from
a prevention trial. It is also inappropriate to conclude from this trial that Ginkgo
extract does not reduce cognitive decline, since there was no cognitive decline to
be reduced, neither in the Ginkgo group nor in the control group.
Recent meta-analyses that adequately considered inclusion diagnoses, extract type
and dosing confirmed the efficacy of Ginkgo biloba leaf extracts standardized according
to the European Pharmacopoeia at a daily dose of 240 mg in dementia and Alzheimer's
1. Birks J, Grimley Evans J: Ginkgo biloba for cognitive impairment and dementia.
Cochrane Database Syst Rev 2009, 1:CD003120.
2. Snitz BE, O'Meara ES, Carlson MC, Arnold AM, Ives DG, Rapp SR, Saxton J, Lopez
OL, Dunn LO, Sink KM, DeKosky ST; Ginkgo Evaluation of Memory Study: Ginkgo biloba
for preventing cognitive decline in older adults: a randomized trial. JAMA 2009, 302:2663-2670.
3. Brautigam MRH, Blommaert FA, Verleye G, Castermans J, Jansen Steur ENH, Kleijnen
J: Treatment of age-related memory complaints with Ginkgo biloba extract: a randomized
double blind placebo-controlled study. Phytomedicine 1998, 5:425-434.
4. Napryeyenko O, Borzenko I; GINDEM-NP Study Group: Ginkgo biloba special extract
in dementia with neuropsychiatric features. A randomized, placebo-controlled, double-blind
clinical trial. Arzneimittelforschung 2007, 57:4-11.
5. Mazza M, Capuano A, Bria P, Mazza S: Ginkgo biloba and donepezil: a comparison
in the treatment of Alzheimer's dementia in a randomized placebo-controlled double-blind
study. Eur J Neurol 2006, 13:981-985.
6. McCarney R, Fisher P, Iliffe S, van Haselen R, Griffin M, van der Meulen J, Warner
J: Ginkgo biloba for mild to moderate dementia in a community setting: a pragmatic,
randomised, parallel-group, double-blind, placebo-controlled trial. Int J Geriatr
Psychiatry 2008, 23:1222-1230.
7. IQWiG Institute for Quality and Efficiency in Health Care. IQWiG Reports �� Commission
No. A05-19B, Ginkgo in Alzheimer's disease. Executive Summary. K��ln: IQWiG, 2008:
8. Kasper S, Schubert H: Ginkgo biloba extract EGb 761�� in the treatment of dementia:
Evidence of efficacy and tolerability [Ginkgo-Spezialextrakt EGb 761�� in der Behandlung
der Demenz: Evidenz f��r Wirksamkeit und Vertr��glichkeit]. Fortschr Neurol Psychiat
2009; 77: 494-506.
9. Weinmann S, Roll S, Schwarzbach C, Vauth C, Willich SN: Effects of Ginkgo biloba
in dementia: systematic review and meta-analysis. BMC Geriatr 2010, 10:14.
10. Wang BS, Wang H, Song YY, Qi H, Rong ZX, Wang BS, Zhang L, Chen HZ: Effectiveness
of Standardized Ginkgo biloba Extract on Cognitive Symptoms of Dementia with a Six-Month
Treatment: A Bivariate Random Effect Meta-Analysis. Pharmacopsychiatry 2010, 43:86-91.
Dr. Kasper has received grant/research support from Bristol Myers-Squibb, Eli Lilly,
GlaxoSmithKline, Lundbeck, Organon, Sepracor and Servier; has served as a consultant
or on advisory boards for AstraZeneca, Bristol-Myers Squibb, Eli Lilly, GlaxoSmithKline,
Janssen, Lundbeck, Merck Sharp and Dome (MSD), Novartis, Organon, Pfizer, Schwabe,
Sepracor, and Servier; and has served on speakers�� bureaus for Angelini, AstraZeneca,
Bristol Myers-Squibb, Eli Lilly, Janssen, Lundbeck, Pfizer, Pierre Fabre, Schwabe,
Sepracor, and Servier.
BioMed Central Ltd unless otherwise stated. Part of Springer Science+Business Media.