Prospective memory, emotions and Alzheimer's disease

Prospective memory (PM) refers to the ability to implement intended actions in 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 AD patients generally better memorise information with a positive emotional valence ("age-related positive effect"). Our hypothesis was that prior presentation of cue-action pairs would help subjects recall the prospective tasks to be performed, 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 of viewing a video simulating a visit to a shopping centre. After receiving a shopping list, participants had to recall these actions after a given time (time-based) or when passing in front of particular stores (event-based). During the learning phase, 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 healthy subjects in "event-based" tasks associated with a positive valence, although only when the link between the cues and the actions was strong. Associating positive stimuli with strongly linked cue-action pairs seems to allow AD patients to compensate for their difficulties in prospective memory. These results open avenues for future research into the rehabilitation of PM disorders in Alzheimer's disease.