The relationship between measures of working memory and sentence comprehension in patients with Alzheimer's disease

Patients with dementia of the Alzheimer's type (DAT) and age- and education -matched older volunteers were tested on a battery of working memory tests, as well as on two tests of sentence comprehension. Patients had reduced sp ans and impaired central executive processes in working memory but showed n ormal effects of phonological and articulatory variables on span. On the se ntence comprehension tasks, DAT patients showed effects of the number of pr opositions in a sentence but not of syntactic complexity. Impairment in the central executive processes of working memory in DAT patients was correlat ed with the effect of the number of propositions in a sentence on the sente nce comprehension tasks. The results suggest that patients with DAT have wo rking memory impairments that ore related to their ability to map the meani ngs of sentences onto depictions of events in the world.