The nature of semantic memory deficits in Alzheimer's disease

Summary While semantic memory deficits are a common landmark integrity of the same concepts. This protocol was given to 53 Alzheimer's disease patients with mild to moderate of Alzheimer's disease, the nature of these impairments dementia and to 20 controls. The Alzheimer's disease remains to be clarified. Implicit tasks which assess group as a whole obtained significantly greater priming semantic priming effects are often used to understand effects (hyperpriming) than controls in the coordinate semantic deficits in Alzheimer's disease, but they have condition, and equivalent priming in the attribute led to unclear conclusions because of methodological condition. In the coordinate condition, a subgroup of 26 problems such as intervention of attentional mechanisms. patients, with attribute knowledge deficits, had larger To explore the effects of semantic priming in Alzheimer's priming effects than both a subgroup without semantic disease and their relationship with semantic memory deficits and the control group. These results show that in deficits, we used two tasks, one implicit and the other Alzheimer's disease the semantic priming effects vary explicit. The implicit task was a lexical decision task to according to the degree of attribute loss, and the presence assess semantic priming, and in which pairs of words had of hyperpriming would reflect semantic memory deficits. coordinate (tiger-lion) or attribute relationships (zebra- This study unravels the fine-grained structure of semantic stripe). The explicit task was a semantic knowledge task memory disturbances in Alzheimer's disease with mild to composed of namings and questions involving moderate dementia, affecting initially the attributes of superordinate categories and attribute knowledge of concepts within a hierarchical network in which superordinate concepts remain preserved. concepts. The two tasks systematically assessed the