Memory and knowledge in mild Alzheimer's disease

The general aim of the present doctoral thesis was to examine the potential ability of mild AD patients to utilize semantic knowledge in different forms to enhance episodic memory performance, as well as to investigate the ability to retrieve and monitor general knowledge in these patients. The study samples included mildly demented AD patients and control groups of normal older adults. Study I focused on the ability of mild AD patients to utilize self-generated retrieval cues as an aid for verbal recall, and whether the factors that promote cue utilization are the same in AD and normal aging. Study II and III examined the ability to utilize semantic knowledge in form of categorical information and prior knowledge to improve memory for pictures of objects and faces, respectively. The ability to utilize the examined forms of support were found to be well preserved in mild AD, although the level of support required to show memory improvement seems to be higher in mild AD than in normal aging. Study IV and V examined the metacognitive ability to monitor the own semantic knowledge base, and the relationship between level of general knowledge and memory monitoring in fact retrieval.

Results indicated intact monitoring of stored information in AD, despite deficits in knowledge retrieval. In addition, the ability of knowledge monitoring in mild AD and normal aging alike seems to be relatively independent of the amount of knowledge possessed. Overall, the five studies indicated that the ability to utilize semantic knowledge in different forms as an aid to enhance episodic remembering, as well as the ability to monitor stored semantic knowledge is well preserved in mild AD. In addition, when differences in patterns of performance between mild AD patients and normal older adults occurred, these were largely found to be of quantitative, rather than of qualitative nature.