An Incidental Learning Method to Improve Face-Name Memory in Older Adults With Amnestic Mild Cognitive Impairment

Implicit processes enhance cognitive abilities in mild cognitive impairment

Previous work has shown that older adults with typical age-related memory changes (i.e., without cognitive impairment) pick up irrelevant information implicitly, and unknowingly use that information when it becomes relevant to a later task. Here, we address the possibility that implicit processes play a similarly beneficial role in the cognitive abilities of individuals with amnestic mild cognitive impairment (aMCI). Twenty-two individuals with aMCI and 22 matched controls participated in a picture judgment task while instructed to ignore distractions in the form of word/non-word letter strings. Memory for the distracting words was later tested with a word-fragment completion task. Both groups showed a priming effect, that is, they were significantly more likely to solve fragments of previously presented than non-presented words. However, the aMCI group had significantly higher scores than the older adults without cognitive impairment, t(42) = 2.16, p < .05, Cohen's d = 0.67. Our findings suggest that individuals with aMCI can enhance their performance on an explicit cognitive task, in this case, word-fragment completion, if previously exposed to the relevant information implicitly, opening up possible interventions aimed at this population.

Time of Day Effects on Inhibitory Functioning: Cognitive and Neural Evidence of Sundowning in Amnestic Mild Cognitive Impairment

Background: Amnestic mild cognitive impairment (aMCI), a prodromal phase of Alzheimer’s disease (AD), is characterized by episodic memory dysfunction, but inhibitory deficits have also been commonly reported. Time of day (TOD) effects have been confirmed in 1) healthy aging on cognitive processes such as inhibitory control, and 2) on behavior in AD (termed the sundowning effect), but no such research has addressed aMCI. Objective: The present study examined the impact of TOD on the behavioral and electrophysiological correlates of inhibition in 54 individuals with aMCI and 52 healthy controls (HCs), all of morning chronotype. Methods: Participants were randomly assigned to complete two inhibition tasks (Go-NoGo and Flanker) during their optimal (morning) or non-optimal (evening) TOD, while electroencephalography was recorded. Results: Both tasks elicited changes in N2 and P3 event-related potential (ERP) components, which commonly index inhibitory functioning. Analyses showed that the Go-NoGo difference in P3 amplitude was reduced in individuals with aMCI relative to HCs. Compared to HCs, the Flanker difference in P3 amplitude was also reduced and coincided with more errors in the aMCI group. Notably, these behavioral and ERP differences were exaggerated in the non-optimal TOD relative to the optimal TOD. Conclusion: Findings confirm the presence of inhibition deficits in aMCI and provide novel evidence of sundowning effects on inhibitory control in aMCI. Results reinforce the need to consider the influences of TOD in clinical assessments involving individuals with aMCI.

Older Adults Encode Task-Irrelevant Stimuli, but Can This Side-Effect be Useful to Them?

We studied whether, due to deteriorating inhibitory functions, older people are more likely to process irrelevant stimuli; and if so, could they later use this information better than young adults. In the study phase of our experiment, a Posner-type gaze-cued version of a Simon task was performed in which we presented task-irrelevant cues, where faces or patches with either left- or right-looking dots for the pupil of the eye preceded the task to press a button congruent or incongruent with the presentation side of the target stimulus. In the follow-up test phase, participants completed an unexpected facial recognition test. In the study phase not only a decreased P1, but also an increased N170 amplitude of the event-related potentials (ERPs) were found in older, compared to younger adults, and also for faces compared to patches. Even though in the test phase both age-groups could recognize the faces better than statistically by chance, neither the older nor the younger participants could discriminate them effectively. The late positive component (LPC)—the ERP correlates of the old/new effect, being the higher amplitude for the earlier presented stimuli when compared with the unseen stimuli during the recognition test—was not evolved in the older group, while a reversed old/new effect was seen in younger participants: higher amplitude was found in New-Right and Old-Wrong conditions (for faces they did not recognize independent of seeing them before) compared to Old-Right and New-Wrong conditions (for faces they thought they recognized from the study phase). In conclusion, although older adults showed enhanced processing of task-irrelevant stimuli compared to younger adults, as indicated by the N170 amplitude, however, they were not able to utilize this information in a later task, as was suggested by the recognition rate and LPC amplitude results.