The pattern of reading deterioration in dementia of the Alzheimer type: observations and implications.

Thirteen patients with dementia of the Alzheimer type (DAT) were tested for their ability to read aloud and to read with comprehension. Reading aloud was preserved in all but the most severely impaired cases and was found to be relatively independent of intellectual deterioration. Reading comprehension declined progressively with increasing dementia severity and correlated well with quantitative mental status assessments. The results suggest that the pattern of reading deterioration may aid in the clinical identification of DAT, that the disturbance of reading comprehension is a linguistic deficit rather than a product of visual-perceptual disturbances, and that the alexia is more consistent with an instrumental loss than a de-developmental model of dementia.