Novelty-related memory effect in amnestic Mild Cognitive Impairment

The detection and processing of novelty plays a critical role in memory function. Yet, relatively little is known about how novelty influences learning in memory-impaired populations, such as Alzheimer’s disease and its early stage, amnestic Mild Cognitive Impairment (MCI). In the current study, 20 patients with amnestic MCI and 20 age- and education-matched healthy older individuals performed a task using the Von Restorff paradigm. Participants studied 22 lists of 10 words. Among those lists, 18 contained an isolate word, which differed from the others in terms of font size. The isolate word could take one of 3 different font sizes (90-point, 120-point or 150-point), whereas other non-isolate words were shown in 60-point font size. The remaining four lists were control lists that contained no isolate word. After studying each list, participants had to freely recall as many words as possible. When the isolate words were presented in 120-point or 150-point font size (but not in 90-point font size), both amnestic MCI patients and healthy older adults recalled them more often than other words (excluding primacy and recency effects). Novelty-related memory benefit was computed as the difference between recall score for the isolate words and recall score for the other words. A group by font size ANOVA revealed no group effect, nor any interaction, suggesting that amnesic MCI patients benefited from novelty similarly as healthy older adults. Moreover, patients had impaired primacy effect (sometimes described as related to contextual novelty). The preservation of the boosting effect of isolation-related novelty on subsequent recall despite impaired episodic memory in the patients is interesting to consider at the light of divergent theoretical viewpoints relative to the relationship between novelty and memory, as either parts of the same continuum or independent functions.