Category-specific semantic impairment in Alzheimer's disease and temporal lobe dysfunction: A comparative study

Abstract

In this paper we report an in-depth case study of a patient suffering from Alzheimer's disease who presented with a category-specific disorder relating to processing of knowledge about animate objects in the presence of spared knowledge of inanimate objects. Impairments appeared not only in a confrontation naming task but also on a range of visual knowledge tasks, such as drawing from memory or part-whole matching. The pattern of impairment was compared to that shown by a post-encephalitic patient who manifested a well-documented category-specific deficit for animate objects. Both patients' performance was compatible with an interpretation in terms of impairment at the level of the structural description of objects within the semantic system, as general encyclopaedic knowledge was largely preserved. Temporal lobe damage may be the cause of memory breakdown in both patients.