Profile of memory impairment and gray matter loss in amnestic mild cognitive impairment

Abstract

The present study assessed the patterns of cortical gray matter (GM) loss in patients with amnestic mild cognitive impairment (aMCI) with distinct profiles of memory impairment, i.e. aMCI patients failing on both recall and recognition memory vs. aMCI patients showing impaired recall but preserved recognition memory. This distinction is usually not taken into account in studies on aMCI and the aim of the present study was to assess whether this distinction is useful. Twenty-eight aMCI patients and 28 matched controls subjects were included. All aMCI patients failed a recall memory task (inclusion criteria). All underwent a visual recognition memory task (DMS48). However, 12 succeeded on this task while 16 failed. Relative gray matter (GM) loss was measured using voxel-based morphometry. When comparing aMCI patients to controls regardless of the profile of memory impairment, GM loss was found in temporal, parietal and frontal areas. However, in aMCI patients with preserved recognition (but impaired recall), GM loss was confined to frontal areas. This contrasted with GM loss in the right medial temporal lobe and bilateral temporo-parietal regions in aMCI patients with impaired recall and recognition memory, a pattern of GM loss usually described in early AD. We conclude that different profiles of memory impairment in aMCI patients are associated with distinct patterns of GM loss.