Informant-Based Tool Is Good Screen for Alzheimer's

AD8 screen correlates strongly with Alzheimer's disease biomarkers

09 oct 2010 -- A brief informant-based dementia assessment can identify Alzheimer's disease better than more traditional methods and may be a lower-cost alternative for Alzheimer's screening, according to a report published online Sept. 7 in Brain.

James E. Galvin, M.D., of Washington University in St. Louis, and colleagues developed and tested a new, brief dementia screening test -- the Ascertain Dementia 8 (AD8) questionnaire, which is administered to friends or family members who know the patient very well -- to ascertain observed changes in memory and behavior in 257 patients. The purpose of the study was to validate the AD8 against traditional biomarkers, such as those found in spinal fluid assays and brain plaque scans, as well as cognitive testing methods for Alzheimer's disease screening.

The researchers found that patients who had positive AD8 scores had abnormal Pittsburgh compound B binding and cerebrospinal fluid biomarkers compared with individuals who had negative AD8 scores. The AD8 was also better at detecting early stages of dementia than the Mini Mental State Examination.

"We found a strong relationship between the AD8, a brief, informant-based dementia screening tool, and biomarkers of Alzheimer's disease. Individuals with AD8 scores of greater than or equal to two had a biomarker phenotype (positive PiB binding, low CSF Aβ42, high tau, high tau phosphorylated at threonine 181) consistent with Alzheimer's disease," the authors write. "A positive AD8 screening test corresponded to lower performance on tests of episodic memory, supporting a clinical phenotype of Alzheimer's disease."

Two of the authors hold the copyright for the AD8; another author is a consultant for Avid Radiopharmaceuticals.

Abstract
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