THE NEUROCOGNITIVE BASIS OF WORD-FINDING DIFFICULTY IN ALZHEIMERS-DISEASE

Past research has indicated that deficits in the areas of visual perce ption, semantic memory, and word availability may each underlie the wo rd-finding difficulty observed in dementia of the Alzheimer type. This study attempted to evaluate the independent contribution of deficits in each of these cognitive domains to naming ability in a single sampl e of patients. In comparison to a group of age- and sex-matched normal controls, performance by the mid to moderate Alzheimer patients indic ated deficits in all three functional areas. Using multiple linear reg ression, with dementia severity, knowledge of word meaning, and visuop erceptual processing as predictors, 59.6% of naming variance was accou nted for. However, after controlling for the nonspecific effects of de mentia on naming, knowledge of word meaning remained as the only speci fic deficit which continued to predict naming accuracy. Measures of vi sual perception and word availability were independent of naming abili ty. The results were interpreted as indicating that in the mild to mod erate stages of disease progression, dysnomia is a sensitive index of the generalised effects of dementia with a specific component due to i mpairment in semantic memory, which is independent of visuo-perceptual and word-availability processes.