Reduced Benefit of Memory Elaboration in Older Adults with Subjective Memory Decline

Background: Cognitive interventions for neurodegenerative diseases, such as Alzheimer's disease (AD), are best targeted at the preclinical stages, and subjective memory decline (SMD) without objective memory impairment on standard tests in older adults may represent a very early preclinical stage. Elaborated encoding effectively enhances memory performance for healthy older adults (HOAs), but has not been examined in people with SMD. Objective: To examine elaborated encoding in people with SMD, compared with HOAs. Methods: Participants were 32HOAs and 22 people with SMD, defined using the Memory Complaint Questionnaire. Participants completed a verbal paired associate learning (PAL) task with delayed recall under elaborated and non-elaborated encoding conditions, as well as the California Verbal Learning Test-II. Results: On the PAL learning trials, with age controlled, a significant interaction of group X encoding condition emerged, F(1, 51) = 6.47, MSE = 6.54, p = 0.014, eta(2)(p) = 0.11. Simple main effects revealed no differences between groups in the non-elaborated condition, but in the elaborated condition HOAs recalled more pairs than SMD, although both groups benefited from elaboration. At delayed recall, HOA recalled more pairs than SMD, F(1, 51) = 4.59, p = 0.037, eta(2)(p) = 0.08, and both groups benefited from elaboration, F(1, 52) = 19.25, p < 0.001, eta(2)(p) = 0.27. Conclusion: People with SMD benefit from elaborated encoding, although not to the same extent as HOAs. This objective difference in complex learning and memory suggests neural changes in SMD that may represent preclinical AD. Elaborated encoding is a promising technique to help maintain memory and decrease anxiety in this at-risk population.