Category and attribute knowledge deterioration in Alzheimer's Disease

Abstract

Changes associated with Alzheimer's Disease (AD) in the association cortices of temporal, occipital, and parietal lobes of the brain, result in significantly impaired performance of AD subjects on tests of semantic memory. The most prevalent theory regarding the deterioration of semantic memory is that it is a bottom-up process. That is, the knowledge of attributes becomes lost or inaccessible prior to the knowledge of categories. Previous research of this theory has resulted in conflicting results. The purpose of this study was to test further the theory, while taking into account task difficulty. Thirty probable AD and 28 normal elderly subjects were administered tasks of attribute and categorical knowledge. Results revealed significant differences in performance as a result of task difficulty. These results call into question the methodology previously used to assess the bottom-up theory, as well as the ability to use attribute and categorical knowledge separately.