Sentence comprehension in patients with Alzheimer's disease.

Twenty-three early-stage dementia of the Alzheimer type (DAT) patients and twenty-three control subjects were tested on a sentence-picture matching test containing nine different sentence types representing different levels of syntactic complexity. Subjects chose between drawings depicting a target sentence and a syntactic foil. Results indicated that DAT patients differed from control subjects on four of the nine sentence types. Performance of the patients was not poorer for sentences that were syntactically more complex, but was poorer for sentences that had two propositions as compared to one. Results are discussed in terms of a post-interpretative processing impairment in sentence comprehension in DAT.