Prospective memory, emotions and Alzheimer's disease

Abstract

Prospective memory (PM) refers to the ability to implement intended actionsin the future. PM is particularly affected in the early stages of Alzheimer's disease (AD). The main objective of this study was to examine the links between PM and emotions in AD. Since it has been shown that generally AD patients memorize a better information with emotional positive valence ("age-related positive effect"). Our hypothesis was that prior presentation of cue-action pairs to memorize would help to remember the prospective tasks to perform, if these actions were associated with emotional valences. Twenty patients with mild AD and 20 healthy participants were included in this study. The experimental protocol consisted in viewing a video simulating a visit to a shopping center. After receiving a shopping list, participants had to recall these actions after a given time ("time-based") or passing in front of particular stores ("event-based"). During the training, actions were associated with positive, negative or neutral cues. We also manipulated the task difficulty by giving weak or strong cue-action links, and by introducing distractors. The results showed that the patients' performance was significantly lower than that of the healthy elderly participants both in "event-based" and "time-based" task conditions. However, patients obtained scores similar to those obtained by elderly heathy subjects in "event-based" tasks associated with positive valence, and only when the link between the cues and the actions was strong. Associating positive stimuli with strong linked cue-action pairs seems to allow AD patients to compensate their difficulties in prospective memory. These results open avenues of future research for the rehabilitation of PM disorders in Alzheimer's disease.