Forgetting of the recollection and familiarity components of recognition in patients with amnestic mild cognitive impairment

Introduction: Patients with amnestic mild cognitive impairment (a-MCI) are deficient in storing memory traces relative to recollective forms of declarative memory. Controversial data have, instead, been reported concerning the storage of new memory traces relative to familiarity, with some studies reporting impairment and others sparing of the storage of this form of memory. No data have been reported concerning the consolidation of recollection and familiarity memory traces subsequent to their storage. Methods: To investigate consolidation deficits resulting in accelerated forgetting of the memory trace, we submitted 16 patients with a-MCI and 19 age-matched normal controls (NC) to a verbal version of the experimental paradigm devised by Huppert and Piercy (1977, Neuropsychologia, 15, 643; 1978, Nature, 275, 317), which we modified to obtain a subjective judgement of the memory process (i.e., recollection or familiarity) for each remembered word that had prompted the 'old' response. The y/n recognition tests with a remember/know paradigm were given 10 min, 1 hr, and 24 hr after the study phase. Results: Data demonstrated that patients with a-MCI forgot the memory traces relative to both the recollection and the familiarity components of recognition at the same rate as NC. Conclusions: Evidence was particularly strong for the familiarity component (where a-MCI patients scored the same as NC at all three delay intervals), but was less robust for the recollection data (where an equivalent forgetting rate across the three delay intervals could be demonstrated only for subgroups of a-MCI patients and NC who obtained comparable scores on the 10-min test).