Progressive non-fluent aphasia is not a progressive form of non-fluent (post-stroke) aphasia

Background: The speech of patients with progressive non-fluent aphasia (PNFA) has been described as similar to that in non-fluent aphasia (NFA) consequent on stroke. There are, however, few direct empirical comparisons of these two patient populations in the literature. Aims: To test the hypotheses that PNFA cases differ from NFA (a) in the extent to which their speech production deficit varies as a function of speaking task, and (b) in the nature of their phonological deficit. Methods & Procedures: Groups of PNFA and NFA patients (N = 10 each), matched on scores in a picture-naming test, were assessed on tasks of narrative picture description, reading aloud of text and single words, and phonological abilities such as rhyme judgement and rhyme production. Outcomes & Results: (a) The NFA cases showed equivalent speech rates in self-generated speech and reading text aloud, and equivalent error rates when reading text or isolated single words. In contrast, the PNFA cases spoke more rapidly when reading aloud than when producing narrative speech, and achieved higher accuracy when reading single words aloud than when reading words in text. (b) Variation in success rate for reading different types of words (e.g., content words, function words, and nonsense words), error types in reading, and performance on phonological tasks all indicated a different and better quality of phonological processing in PNFA than NFA. Conclusions: Despite some surface similarities, there are telling differences between the speech impairments in PNFA and NFA. The deficit in PNFA particularly compromises self-generated connected speech.