The Influence of Ongoing Task Change on Event-based Prospective Memory in Patients with Mild Cognitive Impairment

Abstract

With the increasing of aging and life expectancy, more attention was drawn to Alzheimer's disease. Mild cognitive impairment and its effects have come to the vision of scholars due to it's high risk of Alzheimer's disease. Previous studies about mild cognitive impairment have focused on the executive function, visual spatial, episodic memory, language skills etc. Recent researches indicated that the performance of prospective memory was worse in patients with mild cognitive impairment than that in normal elder. In the literatures, In the literatures, few studies had been found to explore the influence of ongoing task change on event-based prospective memory in patients with mild cognitive impairment. This research mainly focused on two questions:(1) the difference of prospective memory between individuals with mild cognitive impairment and normal elderly;(2) the influence of ongoing task change on prospective memory in the two groups. We recruited 96 participants and followed a 2(group: mild cognitive impairment patients, normal elderly) × 3(ongoing task change: non-change, order-change, random-change) between-subjects design to address the above issues. Firstly, two groups of the participants were screened—mild cognitive impairment / normal elderly by measuring Activities of Daily Living(ADL), Mini-Mental State Examination(MMSE) and Clinical Dementia Rating(CDR). Then, the classic paradigm of prospective memory was applied to test the event-based prospective memory performance in the two groups. The ongoing task required participants to judge the outline or the color of stick drawings. The event-based prospective memory task needed participants to press the space key whenever they saw any of the three target cues. The dependent variables were the accuracy and response latency of the event-based prospective memory tasks as well as the ongoing tasks. The results suggested that:(1) prospective memory performance of the patients with mild cognitive impairment was significantly lower than that of the normal elderly. That is, remarkable impairment appeared in patients with mild cognitive impairment;(2) for the patients with mild cognitive impairment, response latency of prospective memory and ongoing task was significantly decreased with the changing of ongoing tasks. The results supported the strategic process theory of prospective memory. It proves that the deficits in executive function might cause the prospective memory failures in patients with mild cognitive impairment.