Familiarity in Mild Cognitive Impairment As a Function of Patients' Clinical Outcome 4 Years Later

Objectives: The current study addresses the nature of memory difficulties in amnestic mild cognitive impairment (aMCI). Whereas recollection is consistently found to be impaired in aMCI, the results on familiarity are divergent. One potential factor that could explain this divergence in findings relates to the heterogeneity of aMCI patients, so that only those aMCI patients who develop Alzheimer disease (AD) may present with impaired familiarity. The present study aimed at testing this hypothesis.

Methods: A group of 45 aMCI patients and a group of 26 healthy older adults performed a verbal recognition memory test with the Remember/Know paradigm to assess recollection and familiarity processes. All participants were followed for 4 years with clinical and neuropsychological testing. At the end of follow-up, 22 aMCI patients progressed to AD and 23 aMCI patients remained stable. Initial memory performance was compared between the 3 groups.

Results: Whereas recollection was severely diminished in all aMCI patients, familiarity accuracy (and consequently global recognition accuracy) was found to be impaired only in aMCI patients who subsequently developed AD.

Conclusion: These findings suggest that the enrichment of the aMCI population with predementia stage patients may modulate the likelihood to observe familiarity deficits, and impaired global recognition accuracy may accompany incipient AD.