Functional correlates of prospective memory in stroke

Abstract

Introduction: Prospective memory is the ability to remember actions to be performed later in time or when a certain event occurs. Multiple cognitive processes are involved in prospective memory, and the degree to which automatic or effortful processes are involved may differ for different types of prospective memory tasks. This study aimed to investigate prospective memory (dys)functioning in stroke patients, and to get more insight in which cognitive processes are involved in time- versus event-based prospective memory.

Methods: We investigated 39 community-dwelling stroke survivors and 53 matched control participants. Assessment included naturalistic and experimental event- and time-based prospective memory tasks, as well as standard neuropsychological measures of (retrospective) memory, processing speed and attention/executive functioning.

Results: 41% of the stroke patients performed significantly worse than control participants on prospective memory tasks. Deficits in prospective memory occurred as frequently as impairments in retrospective memory (33%, χ(2)(1, N=39)=3.4, p=.066), and more often than impairments in attention/executive functioning (15%, χ(2)(1, N=39)=5.2, p=.022) and speed of processing (23%, χ(2)(1, N=39)=6.5, p=.011). Regression analyses showed that event-based ('focal') prospective memory is supported by retrospective memory, indicating that it is a relatively simple and automatic process. Time-based (non-'focal') prospective memory proved to be a more complex process, requiring active monitoring of the environment. Performance was predicted by speed of processing, attention/executive functioning and retrospective memory. Thirteen percent of the patients suffered from selective prospective memory impairment, which was associated with damage to the superior temporal gyrus.

Conclusions: Impairment of prospective memory occurs frequently after stroke. Different cognitive operations are involved in distinct types of prospective memory. Results fit within the multi-process framework of prospective memory and help further specify its contents.

Keywords: Cognitive functioning; Focality; Monitoring; Prospective memory; Stroke; Superior temporal gyrus.