Using mental imagery to improve memory in patients with Alzheimer disease: trouble generating or remembering the mind's eye?

Abstract

This study was conducted to understand whether patients with mild Alzheimer disease (AD) could use general or self-referential mental imagery to improve their recognition of visually presented words. Experiment 1 showed that, unlike healthy controls, patients generally did not benefit from either type of imagery. To help determine whether the patients' inability to benefit from mental imagery at encoding was due to poor memory or due to an impairment in mental imagery, participants performed 4 imagery tasks with varying imagery and cognitive demands. Experiment 2 showed that patients successfully performed basic visual imagery, but degraded semantic memory, coupled with visuospatial and executive functioning deficits, impaired their ability to perform more complex types of imagery. Given that patients with AD can perform basic mental imagery, our results suggest that episodic memory deficits likely prevent AD patients from storing or retrieving general mental images generated during encoding. Overall, the results of both experiments suggest that neurocognitive deficits do not allow patients with AD to perform complex mental imagery, which may be most beneficial to improving memory. However, our data also suggest that intact basic mental imagery and rehearsal could possibly be helpful if used in a rehabilitation multisession intervention approach.

Figure 1

Mean percent correct for the Clock Angles (CA), Animal Tails (AT), Taller/Wider (TW) and Letter Curves (LC) imagery tasks for the healthy older adults and patients with AD. The additional dark shaded area above the AD bars represents the means percent correct on these tasks with Boston Naming scores added in the ANOVA as a covariate.