The ADAS is a global rating scale which is used to summarize whether an individual has cognitive impairments consistent with Alzheimer's disease. Test items assess various functions including language ability (speech and comprehension), memory, ability to copy geometric figures, and orientation to current time and place. Patients are given a score for each area, with higher scores indicating more dysfunction. Subjects with Alzheimer's disease tend to score consistently higher than healthy elderly patients.

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The ADAS was originally developed by W. G. Rosen, R. C. Mohs and K. L. Davis ("A new rating scale for Alzheimer's disease," in American Journal of Psychiatry, vol. 141, pp. 1356-1364.)