Components in the breakdown of verbal communication in Alzheimer's disease

Abstract

A retrospective study was conducted on 66 Alzheimer patients and 66 age, education- and sex-matched healthy controls. The broad aim was to gain further understanding of the verbal communication disorders of Alzheimer patients by comparing two tests for their sensitivity to Alzheimer's disease; namely an «active» and a «passive» oral language test; respectively a classic Semantically cued Word Generation (SWG), and a Sentence Comprehension Test, the Token Test (TT). The results show that nearly half of our Alzheimer patients are below cut-off on each test, that only a quarter were impaired both on TT on SWG (often patients impaired on one test were not impaired on the other), and that the two tests were poorly correlated in both healthy controls and Alzheimer patients. Nevertheless, the two tests have a comparable specificity in telling Alzheimer patients apart from matched healthy controls. The different processing sub-components for word generation and sentence comprehension and the impact Alzheimer's disease has on them are discussed. These findings are interpreted in terms of a two-component (namely, verbal, or aphasic, and extra-verbal, or dysexecutive) view of the language disorders of Alzheimer patients, and single cases are shown with a «dissociated» performance on the two tests.