WORD READING IN ALZHEIMERS-DISEASE - CROSS-SECTIONAL AND LONGITUDINALANALYSES OF RESPONSE-TIME AND ACCURACY DATA

Using a list of high-and low-frequency regular and exception words, we measured the reading performance of three groups of subjects: patient s with mild dementia of the Alzheimer's type (DAT) at presentation (St age 1) and 2-3 years later (Stage 2); moderately severe DAT patients, and control subjects. In the longitudinally studied patients, there wa s a dramatic increase in response times (RTs) from Stage 1 to Stage 2, but little change in either error rate of pattern. By contrast, a com parison of the Stage 2 with the Moderate patients revealed similar RTs but a significant increase in error rate for the Moderate group, part icularly on low-frequency exception words. These two results for word naming were almost exactly mirrored by effects in picture naming. We c onclude that correct word reading, especially for less common words wi th atypical spelling-sound correspondences, is compromised in DAT only when the disease produces a significant deterioration of semantic mem ory. These results are relevant to current theories about normal and i mpaired reading processes. (C) 1998 Elsevier Science Ltd. All rights r eserved.