Semantic organization and verbal episodic memory in patients with mild and moderate Alzheimer's disease

The objective of the present research was to investigate the relationship between semantic organization and cue utilization in mildly and moderately demented patients with Alzheimer's disease (AD). In Experiment 1, subjects were presented with two lists of words: a list with semantically unrelated words and a list with words from four semantic categories presented randomly intermixed. Free recall was assessed and following the organizable list, subjects received a cued recall test. Normal controls, as opposed to mildly and moderately demented patients, showed higher performance in the organizable list as compared to the random list. In addition, normal controls and mildly demented patients benefited from semantic cues in the organizable list and performed at a higher level in total recall as compared to free recall. In Experiment 2, subjects were presented with two lists of words: a list with words from four semantic categories presented randomly intermixed and a list with words from four semantic categories presented clustered, together with information about the organization of the list. Free recall and cued recall, with the category names serving as cues, were assessed. Free recall performance of normal controls was higher in the clustered than in the organizable list, whereas no such effect was observed for the AD patients. Normal controls and mildly demented patients performed at a higher level in total as compared to free recall in both lists, whereas this effect was present only in the clustered list for the moderately demented patients. The overall pattern of results indicates that there are conditions under which memory facilitation from semantic organization may be obtained in AD.