The effects of initiation, termination and inhibition impairments on speech rate in a case of progressive nonfluent aphasia with progressive apraxia of speech with frontotemporal degeneration

Recent research into nonfluent forms of primary progressive aphasia and progressive apraxia of speech has highlighted the importance of speech rate as a diagnostic feature. We describe detailed investigation and comparison of speech rate (latencies and utterance length in single word/nonword production and speech rate in connected speech) on a range of experimental tasks in a man with progressive speech deterioration of 10 years duration from Pick's Disease. C.S. had a progressive nonfluent aphasia (PNFA) together with progressive apraxia of speech (pAOS) with an absence of significant interlectual, phonological or semantic impairment. C.S. showed increased latencies but reduced word length compared to matched controls on single word and nonword repetition and reading, an absence of a syllabic length effect in either single word/nonword tasks or connected speech tasks. Further investigation suggested that underlying his speech production impairments were problems with speech initiation, termination and inhibition. Most impairments worsened with progression over a 12-month period. Results provide support for the view that progressive apraxia of speech presents differently to apraxia of speech following stroke and, especially at advanced stages, involves deterioration in more central and supportive cognitive processes.