Semantic memory in Alzheimer's Disease

Alzheimer's Disease is characterized by a general decline in cognitive functioning. Although phonology are relatively unaffected, patients with Alzheimer's Disease have been reported to have deficits of semantic memory. Thirteen patients with dementia, five of whom had a confirmed diagnosis of dementia, participated in the study. The purpose of this investigation was to replicate a study performed by Mark Byrd (1984), using Alzheimer's Disease patients. Subjects were presented with category-word decision pairs, for which the task was to decide if the word was an exemplar of the category, and category-letter decision pairs for which the task was to generate an exemplar of the category beginning with the letter. The dependent variable was reaction time. Results indicated that Alzheimer's Disease patients and dementia patients had longer reaction times than a group of age-matched control subjects, and that the Alzheimer's Disease and dementia patients showed a pattern of responses similar to that of the control subjects. All groups showed longer reaction times for the generation trials than the decision trials. The results are consistent with the existence of a semantic memory deficit in Alzheimer's Disease, but other interpretations were discussed.Medicine, Faculty ofAudiology and Speech Sciences, School ofGraduat