Semantic Memory Disorders in Alzheimers Disease: Clues from Semantic Priming Effects

Benedicte      Giffard; Beatrice      Desgranges; Francis      Eustache

Abstract

Semantic memory deficits are a common landmark in Alzheimers disease, but the nature of these impairments remains to be clarified. The tests used to explore this memory system are not specific and involve cognitive processes often disturbed in Alzheimers disease. A complementary way to investigate semantic memory in neuropsychology is by using the semantic priming paradigm. Here, semantic priming refers specifically to the modification of a stimulus processing behind the presentation of a related stimulus; it is a short-lived phenomenon considered an implicit measure of semantic memory integrity. However, semantic priming studies have yielded contradictory results in Alzheimers disease, with authors reporting normal priming, less-than-normal priming, or increased priming effects (hyperpriming). The aim of this paper is to review the literature investigating semantic priming in Alzheimers disease, and to discuss the contradictory results in the context of current models of semantic processing. For a clear comprehension of the semantic priming patterns in this pathology, we will precise the methodology used and the characteristics of the Alzheimers disease patients examined. Besides, the surprising hyperpriming phenomenon - often observed in Alzheimers disease at the early stage of dementia - will also be explained in detail. These results from semantic priming represent invaluable clues to widen our knowledge and conceptions about deterioration of the semantic memory in Alzheimers disease.

Keywords: alzheimers disease, semantic disorders, semantic priming