Is emotional memory enhancement preserved in amnestic mild cognitive impairment? Evidence from separating recollection and familiarity

Objective: This study investigated whether the observed absence of emotional memory enhancement in recognition tasks in patients with amnestic mild cognitive impairment (aMCI) could be related to their greater proportion of familiarity-based responses for all stimuli, and whether recognition tests with emotional items had better discriminative power for aMCI patients than those with neutral items. Method: In total, 31 aMCI patients and 30 healthy older adults participated in a recognition test followed by remember/know judgments. Positive, neutral, and negative faces were used as stimuli. Results: For overall recognition performance, emotional memory enhancement was found only in healthy controls; they remembered more negative and positive stimuli than neutral ones. For "remember" responses, we found equivalent emotional memory enhancement in both groups, though a greater proportion of "remember" responses was observed in normal controls. For "know" responses, aMCI patients presented a larger proportion than normal controls did, and their "know" responses were not affected by emotion. A negative correlation was found between emotional enhancement effect and the memory performance related to "know" responses. In addition, receiver operating characteristic curve analysis revealed higher diagnostic accuracy for recognition test with emotional stimuli than with neutral stimuli. Conclusions: The present results implied that the absence of the emotional memory enhancement effect in aMCI patients might be related to their tendency to rely more on familiarity-based "know" responses for all stimuli. Furthermore, recognition memory tests using emotional stimuli may be better able than neutral stimuli to differentiate people with aMCI from cognitively normal older adults.