When the Amnestic Mild Cognitive Impairment Disappears

Abstract

Subjects affected by mild cognitive impairment (MCI) may improve during the observation period. This is the first study investigating qualitative features of memory deficits in subjects affected by reversible MCI [reversible cognitive impairment (RCI)]. Baseline cognitive and memory performances of 18 subjects affected by amnestic MCI who had normalized cognitive performances at follow-ups were compared with those of 76 amnestic MCI subjects who still showed impaired cognitive performances at the 24-month follow-up (MCI) and with those of a group of 87 matched control subjects (normal controls). Compared with normal controls the memory deficit in the MCI group affected all aspects of explicit long-term memory functioning; in the RCI group, instead, the memory deficit only affected the free recall of verbal material, particularly when the encoding could be improved by the use of semantic strategies. These results are consistent with the view that the memory deficit in the MCI group is due to a very early degenerative pathology; in the RCI group, instead, a transitory reduction of processing resources, resulting a poor encoding of incoming material, is likely at the origin of the reversible memory disorder.