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The upcoming Memory Impairment Study is the first such AD prevention clinical trial carried out by NIH, and will be
conducted at 65-80 medical research institutions located in the United States and Canada. This study will test the usefulness of
two drugs to slow or stop the conversion from MCI to AD. The trial will evaluate placebo, vitamin E, and donepezil, an
investigational agent approved by the Food and Drug Administration for another use. Vitamin E (a-tocopherol) is thought to
have antioxidant properties, and was shown in a 1997 study to delay important dementia milestones, such as patients'
institutionalization or progression to severe dementia, by about seven months.
Participants will be randomly assigned to one of the three groups. The study will be carried out in 720 people over a 3-year
period within the NIA's consortium of AD clinical research centers, called the Alzheimer's Disease Cooperative Study
(ADCS). The study will be directed by Dr. Ronald C. Petersen, Ph.D., M.D., of the Mayo Clinic in Rochester, Minnesota, and
Dr. Michael Grundman, M.D., M.P.H., of the University of California at San Diego (UCSD). Dr. Leon Thal, M.D., of UCSD
directs the ADCS.
"While cognitive testing may reveal people with MCI to have a significant memory problem, their other cognitive functions
remain normal and are for the most part unaffected by MCI," said Dr. Thal. "Prior to today, most treatments tested for slowing
memory decline have been evaluated in patients with well-defined AD. What we hope to accomplish in this trial is to test agents
that delay or stop further memory deterioration or the onset of AD in persons with MCI. In order to do that, it is our hope that
as many people as possible with specific memory impairments volunteer to participate in this study."
In a different study, Dr. Petersen and colleagues at the Mayo Clinic compared the cognitive testing results of three groups of
people: people with MCI, patients with mild AD, and people with normal memory. On memory measures, people with MCI
performed worse than those with normal memory and were much more similar to patients with AD. On other cognitive
measures, the MCI individuals were equivalent to people with normal memory and better than the AD patients. Dr. Petersen's
study appears in the March 1999 issue of Archives of Neurology.
Investigators have long been interested in MCI in part because a significant number of people over the age of 65 with the
condition eventually develop AD as many as 12-15 percent of them per year (or about 40 percent after 3 years). Only 1
percent per year (or 3 percent after 3 years) of healthy people over the age of 65 develop AD. While individuals who
eventually develop dementia go through a phase of mild cognitive impairment, some individuals with MCI may never convert to
the clinical stages of AD.
The Memory Impairment Study targets people between the ages of 55 and 90. Those interested in participating in the clinical
trial should have a memory complaint, exhibit memory impairment in testing but be able to perform everyday activities
normally and should not have a clinical diagnosis of Alzheimer's disease. Information on patient recruitment for the trial is
available by calling 1-888-455-0655 and at http://www.memorystudy.org.
Normal memory loss generally associated with aging is characterized by misplacing an item, forgetting someone's name, or
forgetting to pick up something at the store. Memory loss associated with MCI is more severe and involves continuing
problems in delayed recall of information. Abnormal memory loss, associated with dementia, is characterized by even more
severe problems, such as disorientation, an inability to recall very recent events, and general confusion. A number of other
conditions, diseases, and medications can cause many of the symptoms associated with dementia, making correct clinical
"Before now, evaluating people with MCI has been difficult because we haven't had a clear definition of the symptoms of the
disease," says Dr. Marcelle Morrison-Bogorad, Ph.D., Associate Director of NIA for the Neuroscience and Neuropsychology
of Aging Program where the bulk of the Federal Government's Alzheimer's disease research is coordinated. "Now we can use
information from Dr. Petersen's study and related studies to identify people with MCI and to develop ways to prevent or delay
the onset of AD in this high-risk population. To delay or prevent the slide from mild cognitive impairment to dementia, even in a
fraction of people, would have profound effects socially, financially, and otherwise."
The Memory Impairment Study is sponsored by the Alzheimer's Disease Cooperative Study at the University of California, San
Diego with grant funding from the National Institute on Aging and contributions from Pfizer Inc. and Eisai Inc. Additional
support is from Roche Vitamins Inc.
The NIA, one of 25 Institutes and Centers at the National Institutes of Health, leads the Federal effort in studying Alzheimer's
disease and supporting basic, clinical, epidemiological and social research on aging and on the special needs of older people.
Questions and Answers on Launch of NIA Memory Impairment Study
* Ronald C. Petersen, Ph.D., M.D., Glenn E. Smith, Ph.D., Stephen C. Waring, D.V.M., Ph.D., Robert J. Ivnik, Ph.D., Eric
G. Tangalos, M.D., Emre Kikmen, M.D. "Mild Cognitive Impairment: Clinical Characterization and Outcome". Archives
of Neurology. March 1999, pp. 303-308.