Conversational Discourse in Patients with Alzheimer's Disease

While there are numerous studies examining brain mechanisms of phonological, syntactic, and lexicosemantic processing, there has been little research directed toward examining the organic basis of sociolinguistic behavior. This may in part result from differences in the philosophical traditions associated with sociolinguistics and neurolinguistics. We compared discourse production in five patients with mild to moderate probable dementia of the Alzheimer type (DAT) and their five spouses, during open‐ended interviews. We found that DAT patients produced significantly more turns and topic shifts but produced fewer total words, words per turn, unique words, narratives, direct quotes, and figures of speech than did their healthy spouses. Examination of DAT speech samples showed that they were characterized both by a lack of propositional content and illocutionary force, illustrating deterioration in communicative competence. This research is part of an emerging focus in which conversational interaction is considered a window into human brain contingencies.