MEMORY AND COGNITION IN ALZHEIMER'S DISEASE AND AGING

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It is well known that learning and memory depend on adequate attention and cognitive processing of information to be remembered, that cueing is necessary to elicit complete recall of all items from storage, and that effective cueing depends on adequate processing of the cue with its target when information about the target is encoded. Investigation of the apparent memory deficits which seem to be a major feature of aging and dementia has been limited by the difficulty of inducing effective processing at encoding and retrieval. This project will induce encoding of information needed for retrieval by asking the subject to search an array of pictures or words to identify each item as specified by an appropriate cue (such as its category) so that the same cue can be used to elicit cued recall of items not recovered by free recall. Identification of each item shows that the processing has been carried out, that the item can be named, and results in effective cued recall. Speed of cued recall, which reveals differences in memory not shown by number of items recalled, also will be investigated. The long-term objectives are to show that apparent memory deficits of normal healthy aged can be eliminated when processing is controlled, to more accurately assess maximum memory capacity in Alzheimer's disease (AD), and to investigate encoding and retrieval of memory traces by normal aged and patients with AD. The specific aims are to show: that normal aged can learn and remember as well as young but that patients with AD cannot encode or retrieve as much or recall as quickly; that normal aged can encode enough information for recall of each item by two cues and for recall of two items by a single cue, but that patients with AD cannot; that normal aged do not forget more rapidly but that patients with AD do; and that recall failure by normal aged and by patients with AD is due to retrieval failure, and that patients with AD have more retrieval failures. Demonstration of intact learning and memory by normal healthy aged implies that impaired learning and memory despite effective processing is due to disease that may be treatable or preventable. Accurate evaluation of learning and memory capacity when processing is controlled at encoding and retrieval is needed to understand the interaction of memory and cognition in the dementia of AD, to correlate the dementia with neuropathologic changes, and to evaluate the effects.