ABSTRACT
Analysing spontaneous speech in individuals experiencing fluency difficulties holds potential for diagnosing speech and language disorders, including Primary Progressive Aphasia (PPA). Dysfluency in the spontaneous speech of patients with PPA has mostly been described in terms of abnormal pausing behaviour, but the temporal features related to speech have drawn little attention. This study compares speech-related fluency parameters in the three main variants of PPA and in typical speech. Forty-three adults participated in this research, thirteen with the logopenic variant of PPA (lvPPA), ten with the non-fluent variant (nfvPPA), nine with the semantic variant (svPPA), and eleven who were healthy age-matched adults. Participants’ fluency was assessed through a picture description task from which 42 parameters were computed including syllable duration, speaking pace, the duration of speech chunks (i.e. interpausal units, IPU), and the number of linguistic units per IPU and per second. The results showed that each PPA variant exhibited abnormal speech characteristics reflecting various underlying factors, from motor speech deficits to higher-level issues. Out of the 42 parameters considered, 37 proved useful for characterising dysfluency in the three main PPA variants and 35 in distinguishing among them. Therefore, taking into account not only pausing behaviour but also temporal speech parameters can provide a fuller understanding of dysfluency in PPA. However, no single parameter by itself sufficed to distinguish one PPA group from the other two, further evidence that dysfluency is not dichotomous but rather multidimensional, and that complementary multiparametric analyses are needed.
Acknowledgments
We are immensely grateful to Miguel Angel Santos-Santos, a neurologist at the Sant Pau Hospital Memory Unit, for sharing speech samples of individuals used in this research.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Notes
1 The length of speech runs (IPU) should not be confused with the (mean) length of utterances (MLU), a metric broadly used to assess grammaticality and grammatical complexity in post-stroke aphasia or primary progressive aphasia (e.g. Angelopoulou et al., Citation2018; Ash et al., Citation2006, Citation2009, Citation2019; Brisebois et al., Citation2020; Clough & Gordon, Citation2020; Dipper et al., Citation2021; Ghoreishi et al., Citation2020; Gordon, Citation2008; Groenewold, Citation2015; Mandal et al., Citation2020; Rogalski et al., Citation2011; Thompson et al., Citation2013; Tochadse et al., Citation2018; Webster & Morris, Citation2019).
2 Note that, in this study, the issue of multiple testing was not addressed.
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Funding
This work was supported by the Spanish Ministry of Science under grants number [PI19/00882] and [PID2022-139004OA-I00].