Speech and language in progressive nonfluent aphasia compared with early Alzheimer's disease

Background: Progressive nonfluent aphasia (PA) is a slow deterioration of language that remains relatively isolated from other cognitive or behavioral deficits for at least 2 years. The differentiation of PA from early Alzheimer's disease (AD) is important, given the presence of early language changes in AD. Methods: A language assessment was administered to 15 patients who met established criteria for PA, 15 patients with clinically probable AD and mild dementia, and 15 normal control subjects. The language battery included verbal fluency, the Boston Naming Test with cuing and recognition, and an aphasia test battery with a motor speech exam. Results: Pronounced literal paraphasic errors distinguished the PA patients from the AD patients. The PA group had anomia, decreased letter fluency, neologisms, difficulty on phrase repetition, decreased phrase length, and a decreased rate of verbal output. Interference from paraphasic anomia accounted for much of their decreased fluency. Conclusion: Many patients with PA have a primary defect in accessing sound-based representation of speech ( phonemes), similar to conduction aphasia, possibly as a consequence of disturbed white matter tracts in the left superior temporal region.