The Influence of the Stroop Interference Effect on an Event‐based Prospective Memory Task in Alzheimer's Disease Patients

Abstract

Background: Prospective memory is known as the memory of a plan to carry out an intended action in the future. Although it is associated with many activities in everyday life, to date there have been no well controlled laboratory studies of prospective memory in patients with Alzheimer's dementia (AD). In this study, we investigated the ability of prospective memory in AD subjects using an event‐based prospective memory task in which prospective remembering is triggered by a specific external cue. Methods: Using a personal computer, we conducted event‐based prospective memory tasks embedded in the Stroop task. The concurrent cognitive task such as the Stroop task was called the ongoing task. In the event‐based prospective memory task, subjects were required to react by pressing a mouse key whenever a stimulus during the Stroop task (identification of the name of a color printed in black, of the correct color of a colored circle, or the name of a color printed in an incorrect color) appeared in a larger‐than‐normal size. This target stimulus was designed to appear eight times in each condition, i.e., word condition, color condition, and incorrect‐color condition, during the Stroop task. Results: Normal elderly people showed good event‐based prospective memory performance across all three conditions in the Stroop task. In contrast, AD subjects performed poorly in the event‐based prospective memory task under the incorrect‐color condition in the Stroop task. Conclusion: This study indicated that an ongoing concurrent task with a high attention demand affects the performance of event‐based prospective memory in AD subjects. The performance of event‐based prospective memory in AD subjects was more sensitive to the Stroop interference effect observed in the ongoing task than in normal elderly people. The breakdown of this event‐based prospective memory may reflect the limited attention capacity of AD subjects.