Asymmetrical memory decline in normal aging and dementia.

We assessed whether age-associated memory impairments and the memory impairment of Alzheimer's disease (AD) is comparable in the verbal and nonverbal domains. Subjects incidentally learned the identity and location of a group of objects and later verbally recalled the objects as well as recalling their previous spatial location. Comparison subject (younger subjects for experiment 1, and older subjects for experiment 2) were tested after retention intervals that equated their performance with that of the index subjects. We found that memory does not change uniformly with age. Verbal memory is more affected than nonverbal memory. This asymmetrical pattern is a feature of normal aging and does not appear to be due to a degenerative process such as Alzheimer's disease.