Doctors often evaluate a person who is having memory problems by testing them with a variety of cognitive tasks, such as recalling a list of words or comparing shapes of objects. Washington University researchers developed a different approach. The two-minute Ascertain Dementia 8 (AD8) questionnaire relies on a friend or family member who knows the person well, known as an informant, to evaluate whether cognitive changes have caused the individual to have difficulties in performing everyday activities.
In the new study, published online in the journal Brain, scientists validated the AD8 by checking to see if it could highlight individuals who had biological indicators, or biomarkers, for Alzheimer's disease, such as abnormal levels of certain factors in the spinal fluid or positive brain scans for Alzheimer's plaques. The AD8's results corresponded with biomarker results more consistently than traditional cognitive tests.
"It's not economically feasible to screen everyone for Alzheimer's disease biomarkers," says John C. Morris, MD, director of the Charles F. and Joanne Knight Alzheimer’s Disease Research Center at Washington University School of Medicine. "The AD8 gives us a brief and very low-cost alternative that takes a few minutes of the informant's time to screen for dementia and thus identify those individuals who need follow-up evaluations to determine if there truly are signs of Alzheimer's."
According to Morris, the Harvey A. and Dorismae Hacker Friedman Distinguished Professor of Neurology, the difficulty with traditional early-stage dementia screening tools is that they only give a snapshot of a person's cognitive abilities at one point in time — when they're being tested. Asking the individual if his or her mental abilities have changed doesn't necessarily produce accurate results either, Morris says, because persons with early-stage dementia often lack insight into their problem.
Researchers at the Knight Alzheimer' s Disease Research Center, including first author James Galvin, MD, now at New York University, developed the AD8 from the Center’s existing research tools. Informants are asked to rate whether there has been a change in the following areas:Problems with judgment, such as bad financial decisions;
According to Morris, informants who have regular exposure to the individual provide the most accurate assessments.
"These informants can give us the retrospective perspective we need to know that a person's mental abilities have begun to meaningfully decline, indicating that additional testing is needed," Morris says.
For the new study, researchers gathered AD8 evaluations on 251 individuals and also tested them using the Mini Mental State exam, a traditional dementia screening test. They then evaluated biomarkers in the individuals, including spinal fluid assays and brain plaque scans.
"Based on our results, the AD8 appears to be superior to conventional testing in its ability to detect signs of early dementia," Morris says. "It can't tell us whether the dementia is caused by Alzheimer's or other disorders, but it lets us know when there's a need for more extensive evaluations to answer that question."
Since its development, the AD8 has been translated into several different languages and validated in those languages. It is currently in use in clinics around the world.
Galvin JE, Fagan AM, Holtzman DM, Mintun MA, Morris JC. Relationship of dementia screening tests with biomarkers of Alzheimer's disease. Brain, online Sept. 10, 2010.
Funding from the National Institute on Ageing and the National Institutes of Health supported this research.
Washington University School of Medicine's 2,100 employed and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children's hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked fourth in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children's hospitals, the School of Medicine is linked to BJC HealthCare.
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