Patients with amnestic mild cognitive impairment are compromised in temporal order memory.

INTRODUCTION: Temporal disorientation is frequently reported in amnestic mild cognitive impairment (aMCI), yet empirical evidence on temporal order memory in ecologically valid contexts remains scarce. The present study examined temporal order memory in patients with aMCI using a paradigm that captures the temporal organization of everyday activities. METHOD: Twenty-six patients with aMCI and 36 healthy older controls underwent a comprehensive neuropsychological assessment and completed the Temporal Order Memory for Everyday Events (TOMEE) task. Differences in temporal order memory performance between the two groups were analyzed using a General Linear Model. Immediate and delayed recall were assessed, and temporal order memory was analyzed using the total number of items evoked, items evoked in the correct position and in the correct sequence. Indexes of ordinal positioning and of sequential clustering were calculated. Associations between temporal order indexes and episodic memory and executive functioning were explored using correlational analyses. RESULTS: Patients with aMCI recalled fewer items overall than controls. Participants evoked more items in the immediate recall condition than in the delayed free recall condition. Significant differences were also found in the total number of items evoked, items evoked in the correct position and in the correct sequence. An interaction between group and temporal order measures showed that aMCI patients were disproportionately affected in recalling items in the correct temporal order. The index of sequential clustering was lower in patients with aMCI. Temporal order indexes correlated positively with an episodic memory measure (Logical Memory delayed recall) and negatively with the time of an executive function test (Trail Making Test B). CONCLUSIONS: Patients with aMCI show deficits in temporal order memory for everyday events that extend beyond general episodic memory impairment. Alterations in the ability to organize and retrieve temporal sequences may indicate cognitive vulnerability at early stages of neurodegenerative disease.