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Grant Abstract

Grant Number: 5U01AT000162-11

Abstract: This is a proposal for a five year extension of the Ginkgo Evaluation in Memory (GEM) Study, a double- blind, placebo-controlled trial; the largest primary prevention trial of dementia. The primary outcome is the ability of Ginkgo biloba (120mg BID) to prevent or delay the onset of dementia in over 3,000 people 75 years and over. Secondary outcomes include drug-placebo differences in cognitive decline, cardiovascular and cerebrovascular events, functional status and mortality in the cohort. The study screened and recruited 3,072 subjects between October 2000 and May 2002 at 4 clinical sites in the USA, with excellent ongoing retention and compliance. Power calculations required approximately 420 incident cases, utilizing an estimated incidence rate of 3% annually, to ascertain the primary outcome.As with every other prevention trial, the incidence rate was initially lower than expected, with an exponential increase in incidence that has now reached 3%. With 124 incident cases as 9/10/04, the present application seeks to extend subject follow up for up to 4 years, with an additional year for data analyses, site closeout and publication preparation. We will extract DNA and determine apoE genotypes and haplotypes on the entire cohort, and conduct a nested case control study of the incident dementia cases to matched normal controls. The GEMS cohort is one of the largest and most well-characterized (both cognitively and medically) populations of adults over age 75 in the United States. All randomized participants have passed the expected 2 year visit window and < 0.5% are lost to follow-up and 98% have data on cognitive status by either self-report or proxy. For participants reaching their 3.5 year visit (N =597), lost to follow-up remains < 1% and 97% have cognitive status information. Because subjects with both normal cognition and those with mild cognitive impairment (MCI) were enrolled, GEMS will provide us with data on conversion of different types of MCI to dementia as well as the effects of Ginkgo biloba on MCI. A variety of ancillary studies are ongoing and planned for this cohort. Clinical sites will continue in Pittsburgh, North Carolina (Wake Forest), Maryland (Johns Hopkins), and Sacramento (UC-Davis), with Data Management at the Univ. Washington-Seattle, Cognitive Diagnostic Center and Imaging Center at the University of Pittsburgh, Clinical Coordination at Wake Forest, and Lab Resources at the University of Vermont and the University of Pittsburgh. The magnitude of the problem, potential information to be gained, and importance of controlled prevention trials, as well as the success and progress thus far, support extension of this landmark study to completion.

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