Prospective Memory Impairment in Remembering to Remember in Mild Cognitive Impairment and Healthy Subjects

Abstract

The authors of this chapter studied the prospective memory (PM) performance of 20 older people using the message task in delayed recall from the Rivermead Behavioral Memory Test (RBMT) (Wilson, Cockburn, & Baddeley, 1985; Watamori, Hara, Miyamori, & Eto, 2002). Nine of the subjects had mild cognitive impairment (MCI), while the remaining 11 were healthy subjects (HS). The retrievals in PM were divided into two components: remembering to remember and remembering the content (Umeda, & Koyazu, 1998). Cockburn (1995) suggested that four stages existed in the PM retrieval process: encoding, retention, recognition of the prospective memory cue (PM cue) and retrieval of the intended action. The authors administered neuropsychological tests corresponding to each of these stages to investigate the impairment process. Ten subjects showed impairment in remembering to remember and had low performance in encoding, recognition and retrieval in both the auditory verbal memory test and the fluency test, which requires divergent thinking and semantic memory. The other ten subjects were unimpaired, but they also showed low performance in the recognition process of the PM cue with the fluency test. Neither the MCI nor the HS showed impairment in remembering the content. The results suggest that PM impairment in remembering to remember for both MCI and HS results from impairments in frontal lobe function and retrospective memory in the auditory verbal task related to the cue accessibility of spontaneous retrieval.