The effect of semantic orientation at encoding on free-recall performance in amnestic mild cognitive impairment and probable Alzheimer's disease

Abstract

The present study manipulated the nature of orientation provided at encoding in an intentional word memory task. Performance on the memory task was then compared between 23 elderly persons with amnestic mild cognitive impairment (aMCI), 13 patients with probable Alzheimer's disease (AD), and 23 healthy elderly persons. When tested following shallow (reading orientation) encoding, free-recall performance was impaired in AD compared to aMCI and healthy older adults. When tested following deep (categorical semantic orientation) encoding, both AD and aMCI groups were impaired relative to healthy older adults. The latter result was related to larger memory improvement due to semantic orientation in healthy controls than in aMCI and AD participants. Overall, these findings indicate that the encoding put up by aMCI and healthy elderly persons is comparably efficient in situations where shallow supportive cues are provided at encoding, but that healthy controls benefit more than aMCI and AD in situations where supportive cues are strong.

Keywords:

• Amnestic mild cognitive impairment
• Alzheimer's disease
• Aging
• Episodic memory
• Deep encoding
• Semantic orientation

Acknowledgments

This work was supported by a research grant from the Canadian Institutes of Health Research (CIHR; MOP-38063) and a Chercheur National Award from the Fonds de la Recherche en Santé du Québec (FRSQ) to S.B. It was also supported by postdoctoral scholarships from La Fondation des Gouverneurs (Institut Universitaire de Gériatrie de Montréal; IUGM) and the Alzheimer Society of Canada to C.H. Finally, it was supported by a doctoral scholarship award from the CIHR to S.V. The authors are grateful to E. Lepage, C. Proulx, and B. Boudia for their assistance with the testing of participants, and to H. Chertkow (Bloomfield Centre for Research in Aging), S. Gauthier (McGill Center for Studies in Aging), M. J. Kergoat (IUGM), and V. Plante (Centre Hospitalier Universitaire de Québec) for referring amnestic mild cognitive impairment and Alzheimer's disease participants.