Effect of Multiple Sclerosis and Aging on Prospective Memory Using the Ecological Test of Prospective Memory

Objective: Prospective memory (PM) is the ability to remember to produce an action at a specific moment in the future signaled by the occurrence of a specific event (event-based [EB] condition), a time or a time interval (time-based [TB] condition). Detection of the appropriate moment corresponds to the prospective component, while production of the appropriate action corresponds to the retrospective component. Although PM difficulties have been reported in healthy aging and in association with multiple sclerosis (MS), PM has not been examined in older persons with MS (PwMS). The main objective of this study was to investigate whether the decline in PM performance with advancing age is influenced by the presence of MS. This study also aimed to clarify the type of PM impairment (prospective vs. retrospective component in TB and EB conditions) in MS as a function of age. Method: A total of 80 participants were recruited and separated into four groups: older PwMS (n = 20), younger PwMS (n = 20), older controls (n = 20), and younger controls (n = 20). PM and its components were measured using the Test Ecologique de Memoire Prospective (TEMP), an experimental ecological tool using naturalistic stimuli developed by our laboratory that has been validated in previous studies. Results: On the TEMP total score, a two-way analysis of covariance showed a main effect of age, a main effect of the presence of MS, as well as a significant Age x Disease interaction. Direct comparison between EB and TB conditions revealed that for the prospective component, only older PwMS had more difficulty in the TB than in the EB condition, whereas the retrospective component score was significantly lower in the TB than in the EB condition in all groups except in younger controls. Conclusions: The TEMP revealed a marked impairment in PM in older PwMS compared to older controls and young PwMS. This impairment was particularly evident on the prospective component in the TB condition. Retrospective difficulties noted in the TB condition in all, but younger controls reflect the arbitrary nature of the cue-action link that is particularly sensitive to episodic memory difficulties often observed in aging and MS.