Memory function in very early Alzheimer's disease.

The detection of very early Alzheimer's disease (AD) can be important for both theoretical and practical reasons. Typically, a memory impairment is the first sign of incipient disease, but the early clinical diagnosis can be challenging. We investigated several aspects of memory function in AD and normal aging to determine which indices of performance were most sensitive at detecting early impairments. We evaluated 106 pairs of patients with probable AD and matched controls from the Mayo Clinic Alzheimer's Disease Patient Registry using a logistic regression model that included measures of memory function, verbal and nonverbal intelligence, attention, and language. Results indicated that an index of learning, especially with semantic cuing, was most sensitive at separating the two groups. We then matched subsets of individuals from the larger groups of AD and control subjects on the Mini-Mental State Examination (range of scores, 24 to 26). A logistic regression analysis on these matched groups yielded the same results. A measure of learning with facilitation of performance using cues appears to be the best discriminator at detecting very mild AD. These measures can be useful in selecting patients for interventional strategies.