Intrusions in Alzheimer's disease in immediate and delayed memory as a function of presentation modality.

Young and elderly participants, and participants with Alzheimer's disease (AD) were compared via the suffix paradigm, where a not-to-be-recalled item is appended onto sequences to be immediately recalled. This task was followed by delayed tasks. In immediate recall, AD subjects showed both extralist and suffix intrusions. Recall of auditorily as compared with visually presented stimuli was superior, with the difference increasing in older subjects. The auditory but not the visual suffix produced an end-of-sequence decrement, which was greater in AD than in other groups. After delay, the elderly and young showed virtually perfect performance. The AD participants showed relatively high performance; however, extralist intrusions were frequent, resulting in a relatively low hit rate. As in immediate recall, intrusions showed specificity for AD, and in this paradigm appeared to be a marker differentiating AD and normal subjects. However, the sample size limits the power and generalizability of these findings.