Impaired verbal description ability assessed by the Picture Description Task in Alzheimer's disease

Abstract

The language of patients with Alzheimer's disease (AD) is globally non-informative and characterized by selective impairment of lexical-semantic processing as compared with a relative sparing of syntactic and phonological aspects. Verbal picture description is one of the most sensitive tests for detecting language disorders in AD. We assessed verbal description ability in AD and investigated its relation to regional cerebral blood flow (CBF). In part I of the study, 23 AD patients and 17 age-matched normal subjects performed the Picture Description Task, which yields six variables: (1) the amount of information, (2) the number of constituent parts of the picture, (3) the number of relevant and irrelevant descriptions, (4) efficiency of description, (5) appropriateness, and (6) sentence structure. In the study, variables 1, 3 and 4 were analyzed. In part II of the study, regional CBF of 14 of the above AD patients was measured using N-isopropyl- p-[ 123I]iodoamphetamine and single photon emission CT. In part I, there were significant difference between the groups for variables 1 and 4. In part II, there were significant correlations between variable 1 and rCBF in the bilateral occipital lobes and left thalamus. Variables 1 and 4 were useful in discriminating between AD patients and controls. Variable 1 was suggested to be related to the function of the left thalamus and the bilateral visual cortex.