The impact of lexical-semantic impairment and of executive dysfunction on the word reading performance of patients with probable Alzheimer dementia.

The influence of lexical-semantic impairment and of executive dysfunction on word naming performance was investigated in a group of patients with probable Alzheimer dementia (AD). The patients, who varied in the severity of the illness, were tested in a word naming task where they had to read aloud Italian three-syllable words with a dominant or subordinate stress pattern. These types of words have been shown to interact with frequency in normal adults [J. Exp. Psychol.: Hum. Percept. Perform. 18 (4) (1992) 987], so that the effect of the subordinate stress pattern (slower reading times) is only apparent for low frequency words. The frequency and stress effects on accuracy increased across dementia severity levels. Regression analyses showed that the impairment in reading low frequency words with subordinate stress depended largely on the level of lexical-semantic impairment, measured by a test of semantic memory and comprehension. Implications for the current reading models are discussed.