The Memory Impairment Study

A highlight of NIA’s effort to develop effective therapies for AD is the Memory Impairment Study, launched by the Institute in March, 1999. This study is based on the premise that accurate and early evaluation and treatment of individuals with MCI might prevent further cognitive decline, including development of AD. The publication of the earlier research that confirmed that MCI is a distinct clinical entity and, for the first time, characterized its symptoms (see p. 31 for a fuller description of this study), provided a critical foundation for the Memory Impairment Study (Petersen et al., 1999).

The Memory Impairment Study is the first AD prevention clinical trial to be carried out by NIH and is being conducted by the Alzheimer’s Disease Cooperative Study (ADCS), an established nationwide network of research centers supported by the NIA and coordinated by the University of California at San Diego. The ADCS sites will be joined by other clinics and centers around the U.S. and Canada. About 65 sites are participating in the study. The Memory Impairment Study is supported by grant funding from the NIA as well as by contributions from Pfizer, Inc., and Eisai, Inc. Additional support comes from Roche Vitamins, Inc.

Before this study, most treatments tested for slowing memory decline were evaluated in patients with well-defined AD. This trial will test the ability of two agents –vitamin E and donepezil–to intervene earlier, before signs of memory impairment have developed into clinically diagnosed AD. Investigators want to see whether these agents can delay or prevent the onset of AD. The study will be carried out over a 3-year period in 720 people with MCI. The major requirements for participation in the study include recent memory complaints, abnormal memory function on standardized tests, good general health, and no clinical diagnosis of AD. Participants will be randomly assigned to one of three groups–the first group will receive vitamin E, a placebo for donepezil, and a multivitamin; the second group will receive a placebo for vitamin E, donepezil, and a multivitamin; and the third group will receive placebos for vitamin E and donepezil and a multivitamin.

A major challenge for this trial is screening and recruiting individuals who are diagnosed with MCI. Recruitment for AD clinical trials traditionally involves working with Alzheimer’s Disease Centers or other memory disorders clinics to recruit existing patients with clinically diagnosed AD. Because MCI has only recently been defined as a distinct clinical entity, individuals with MCI are not so readily available. To meet this challenge, NIA has developed new recruitment procedures to make people aware of the trial, allow them to sign up, and provide a means for them to come to the study site for a full diagnostic evaluation, treatment, and follow-up. The recruitment procedures developed will be critically important not only for the success of this clinical trial but also for other trials that seek to develop treatments for preventing or delaying the onset of Alzheimer’s.


National Institutes of Health

National Institute on Aging


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