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From the Department of Public Health (H.H.D.), Oregon State University, Corvallis; Department of Epidemiology (H.H.D.), Graduate School of Public Health, University of Pittsburgh, PA; and Layton Aging & Alzheimers Disease Center (H.H.D., T.Z., B.S.O., D.H., J.K.), Oregon Center for Aging & Technology, Oregon Health & Science University, Portland.
Address correspondence and reprint requests to Dr. Hiroko Dodge, 260 Waldo Hall, Department of Public Health, Oregon State University, Corvallis, OR 97401 Hiroko.Dodge{at}oregonstate.edu
Objective: To assess the feasibility, safety, and efficacy of Ginkgo biloba extract (GBE) on delaying the progression to cognitive impairment in normal elderly aged 85 and older.
Methods: Randomized, placebo-controlled, double-blind, 42-month pilot study with 118 cognitively intact subjects randomized to standardized GBE or placebo. Kaplan-Meier estimation, Cox proportional hazard, and random-effects models were used to compare the risk of progression from Clinical Dementia Rating (CDR) = 0 to CDR = 0.5 and decline in episodic memory function between GBE and placebo groups.
Results: In the intention-to-treat analysis, there was no reduced risk of progression to CDR = 0.5 (log-rank test, p = 0.06) among the GBE group. There was no less of a decline in memory function among the GBE group (p = 0.05). In the secondary analysis, where we controlled the medication adherence level, the GBE group had a lower risk of progression from CDR = 0 to CDR = 0.5 (HR = 0.33, p = 0.02), and a smaller decline in memory scores (p = 0.04). There were more ischemic strokes and TIAs in the GBE group (p = 0.01).
Conclusions: In unadjusted analyses, Ginkgo biloba extract (GBE) neither altered the risk of progression from normal to Clinical Dementia Rating (CDR) = 0.5, nor protected against a decline in memory function. Secondary analysis taking into account medication adherence showed a protective effect of GBE on the progression to CDR = 0.5 and memory decline. Results of larger prevention trials taking into account medication adherence may clarify the effectiveness of GBE. More stroke and TIA cases observed among the GBE group requires further study to confirm.
Abbreviations: AD = Alzheimer disease; CDR = Clinical Dementia Rating; CERAD = Consortium to Establish a Registry for Alzheimers Disease; CES-D = Center for Epidemiologic Studies Depression Scale; GBE = Ginkgo biloba extract; mCIRS = modified Cumulative Illness Rating Scale; MMSE = Mini-Mental State Examination Score; OHSU = Oregon Health & Science University; WMS-R = Wechsler Memory Scale-Revised.
e-Pub ahead of print on February 27, 2008, at www.neurology.org.
Supported by P50 AT00066 from the National Center for Complementary and Alternative Medicine, P30 AG08017, and K01 AG023014 from National Institute on Aging.
Disclosure: The authors report no conflicts of interest.
Received June 16, 2007. Accepted in final form September 26, 2007.
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